[PATCH 00/12] mm: Remove pXX_devmap page table bit and pfn_t type

[PATCH 00/12] mm: Remove pXX_devmap page table bit and pfn_t type

[Alistair Popple]

Changes from v2 of the RFC[1]:

 - My ZONE_DEVICE refcount series has been merged as commit 7851bf649d42 (Patch series
   "fs/dax: Fix ZONE_DEVICE page reference counts", v9.) which is included in
   v6.15 so have rebased on top of that.

 - No major changes required for the rebase other than fixing up a new user of
   the pfn_t type (intel_th).

 - As a reminder the main benefit of this series is it frees up a PTE bit
   (pte_devmap).

 - This may be a bit late to consider for inclusion in v6.16 unless it can get
   some more reviews before the merge window closes. I don't think missing v6.16
   is a huge issue though.

 - This passed xfstests for a XFS filesystem with DAX enabled on my system and
   as many of the ndctl tests that pass on my system without it.

Changes for v2:

 - This is an update to my previous RFC[2] removing just pfn_t rebased
   on today's mm-unstable which includes my ZONE_DEVICE refcounting
   clean-up.

 - The removal of the devmap PTE bit and associated infrastructure was
   dropped from that series so I have rolled it into this series.

 - Logically this series makes sense to me, but the dropping of devmap
   is wide ranging and touches some areas I'm less familiar with so
   would definitely appreciate any review comments there.

[1] - https://lore.kernel.org/linux-mm/cover.95ff0627bc727f2bae44bea4c00ad7a83fbbcfac.1739941374.git-series.apopple@nvidia.com/
[2] - https://lore.kernel.org/linux-mm/cover.a7cdeffaaa366a10c65e2e7544285059cc5d55a4.1736299058.git-series.apopple@nvidia.com/

All users of dax now require a ZONE_DEVICE page which is properly
refcounted. This means there is no longer any need for the PFN_DEV, PFN_MAP
and PFN_SPECIAL flags. Furthermore the PFN_SG_CHAIN and PFN_SG_LAST flags
never appear to have been used. It is therefore possible to remove the
pfn_t type and replace any usage with raw pfns.

The remaining users of PFN_DEV have simply passed this to
vmf_insert_mixed() to create pte_devmap() mappings. It is unclear why this
was the case but presumably to ensure vm_normal_page() does not return
these pages. These users can be trivially converted to raw pfns and
creating a pXX_special() mapping to ensure vm_normal_page() still doesn't
return these pages.

Now that there are no users of PFN_DEV we can remove the devmap page table
bit and all associated functions and macros, freeing up a software page
table bit.

---

Cc: gerald.schaefer@linux.ibm.com
Cc: dan.j.williams@intel.com
Cc: jgg@ziepe.ca
Cc: willy@infradead.org
Cc: david@redhat.com
Cc: linux-kernel@vger.kernel.org
Cc: nvdimm@lists.linux.dev
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-ext4@vger.kernel.org
Cc: linux-xfs@vger.kernel.org
Cc: jhubbard@nvidia.com
Cc: hch@lst.de
Cc: zhang.lyra@gmail.com
Cc: debug@rivosinc.com
Cc: bjorn@kernel.org
Cc: balbirs@nvidia.com
Cc: lorenzo.stoakes@oracle.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: loongarch@lists.linux.dev
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-riscv@lists.infradead.org
Cc: nvdimm@lists.linux.dev
Cc: linux-cxl@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: John@Groves.net

Alistair Popple (12):
  mm: Remove PFN_MAP, PFN_SG_CHAIN and PFN_SG_LAST
  mm: Convert pXd_devmap checks to vma_is_dax
  mm/pagewalk: Skip dax pages in pagewalk
  mm: Convert vmf_insert_mixed() from using pte_devmap to pte_special
  mm: Remove remaining uses of PFN_DEV
  mm/gup: Remove pXX_devmap usage from get_user_pages()
  mm: Remove redundant pXd_devmap calls
  mm/khugepaged: Remove redundant pmd_devmap() check
  powerpc: Remove checks for devmap pages and PMDs/PUDs
  mm: Remove devmap related functions and page table bits
  mm: Remove callers of pfn_t functionality
  mm/memremap: Remove unused devmap_managed_key

 Documentation/mm/arch_pgtable_helpers.rst     |   6 +-
 arch/arm64/Kconfig                            |   1 +-
 arch/arm64/include/asm/pgtable-prot.h         |   1 +-
 arch/arm64/include/asm/pgtable.h              |  24 +---
 arch/loongarch/Kconfig                        |   1 +-
 arch/loongarch/include/asm/pgtable-bits.h     |   6 +-
 arch/loongarch/include/asm/pgtable.h          |  19 +--
 arch/powerpc/Kconfig                          |   1 +-
 arch/powerpc/include/asm/book3s/64/hash-4k.h  |   6 +-
 arch/powerpc/include/asm/book3s/64/hash-64k.h |   7 +-
 arch/powerpc/include/asm/book3s/64/pgtable.h  |  53 +------
 arch/powerpc/include/asm/book3s/64/radix.h    |  14 +--
 arch/powerpc/mm/book3s64/hash_hugepage.c      |   2 +-
 arch/powerpc/mm/book3s64/hash_pgtable.c       |   3 +-
 arch/powerpc/mm/book3s64/hugetlbpage.c        |   2 +-
 arch/powerpc/mm/book3s64/pgtable.c            |  10 +-
 arch/powerpc/mm/book3s64/radix_pgtable.c      |   5 +-
 arch/powerpc/mm/pgtable.c                     |   2 +-
 arch/riscv/Kconfig                            |   1 +-
 arch/riscv/include/asm/pgtable-64.h           |  20 +--
 arch/riscv/include/asm/pgtable-bits.h         |   1 +-
 arch/riscv/include/asm/pgtable.h              |  17 +--
 arch/x86/Kconfig                              |   1 +-
 arch/x86/include/asm/pgtable.h                |  51 +------
 arch/x86/include/asm/pgtable_types.h          |   5 +-
 arch/x86/mm/pat/memtype.c                     |   6 +-
 drivers/dax/device.c                          |  23 +--
 drivers/dax/hmem/hmem.c                       |   1 +-
 drivers/dax/kmem.c                            |   1 +-
 drivers/dax/pmem.c                            |   1 +-
 drivers/dax/super.c                           |   3 +-
 drivers/gpu/drm/exynos/exynos_drm_gem.c       |   1 +-
 drivers/gpu/drm/gma500/fbdev.c                |   3 +-
 drivers/gpu/drm/i915/gem/i915_gem_mman.c      |   1 +-
 drivers/gpu/drm/msm/msm_gem.c                 |   1 +-
 drivers/gpu/drm/omapdrm/omap_gem.c            |   7 +-
 drivers/gpu/drm/v3d/v3d_bo.c                  |   1 +-
 drivers/hwtracing/intel_th/msu.c              |   3 +-
 drivers/md/dm-linear.c                        |   2 +-
 drivers/md/dm-log-writes.c                    |   2 +-
 drivers/md/dm-stripe.c                        |   2 +-
 drivers/md/dm-target.c                        |   2 +-
 drivers/md/dm-writecache.c                    |  11 +-
 drivers/md/dm.c                               |   2 +-
 drivers/nvdimm/pmem.c                         |   8 +-
 drivers/nvdimm/pmem.h                         |   4 +-
 drivers/s390/block/dcssblk.c                  |  10 +-
 drivers/vfio/pci/vfio_pci_core.c              |   7 +-
 fs/cramfs/inode.c                             |   5 +-
 fs/dax.c                                      |  55 ++----
 fs/ext4/file.c                                |   2 +-
 fs/fuse/dax.c                                 |   3 +-
 fs/fuse/virtio_fs.c                           |   5 +-
 fs/userfaultfd.c                              |   2 +-
 fs/xfs/xfs_file.c                             |   2 +-
 include/linux/dax.h                           |   9 +-
 include/linux/device-mapper.h                 |   2 +-
 include/linux/huge_mm.h                       |  19 +--
 include/linux/memremap.h                      |  11 +-
 include/linux/mm.h                            |  11 +-
 include/linux/pfn.h                           |   9 +-
 include/linux/pfn_t.h                         | 131 +---------------
 include/linux/pgtable.h                       |  25 +---
 include/trace/events/fs_dax.h                 |  12 +-
 mm/Kconfig                                    |   4 +-
 mm/debug_vm_pgtable.c                         |  60 +-------
 mm/gup.c                                      | 162 +-------------------
 mm/hmm.c                                      |  12 +-
 mm/huge_memory.c                              |  97 ++---------
 mm/khugepaged.c                               |   2 +-
 mm/madvise.c                                  |   8 +-
 mm/mapping_dirty_helpers.c                    |   4 +-
 mm/memory.c                                   |  64 ++------
 mm/memremap.c                                 |  28 +---
 mm/migrate.c                                  |   1 +-
 mm/migrate_device.c                           |   2 +-
 mm/mprotect.c                                 |   2 +-
 mm/mremap.c                                   |   5 +-
 mm/page_vma_mapped.c                          |   5 +-
 mm/pagewalk.c                                 |  20 +-
 mm/pgtable-generic.c                          |   7 +-
 mm/userfaultfd.c                              |   6 +-
 mm/vmscan.c                                   |   5 +-
 tools/testing/nvdimm/pmem-dax.c               |   6 +-
 tools/testing/nvdimm/test/iomap.c             |  11 +-
 tools/testing/nvdimm/test/nfit_test.h         |   1 +-
 86 files changed, 218 insertions(+), 958 deletions(-)
 delete mode 100644 include/linux/pfn_t.h

base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21
-- 
git-series 0.9.1

[PATCH 01/12] mm: Remove PFN_MAP, PFN_SG_CHAIN and PFN_SG_LAST

[Alistair Popple]

The PFN_MAP flag is no longer used for anything, so remove it. The
PFN_SG_CHAIN and PFN_SG_LAST flags never appear to have been used so
also remove them.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/pfn_t.h             | 31 +++----------------------------
 mm/memory.c                       |  2 --
 tools/testing/nvdimm/test/iomap.c |  4 ----
 3 files changed, 3 insertions(+), 34 deletions(-)

diff --git a/include/linux/pfn_t.h b/include/linux/pfn_t.h
index 2d91482..46afa12 100644
--- a/include/linux/pfn_t.h
+++ b/include/linux/pfn_t.h
@@ -5,26 +5,13 @@
 
 /*
  * PFN_FLAGS_MASK - mask of all the possible valid pfn_t flags
- * PFN_SG_CHAIN - pfn is a pointer to the next scatterlist entry
- * PFN_SG_LAST - pfn references a page and is the last scatterlist entry
  * PFN_DEV - pfn is not covered by system memmap by default
- * PFN_MAP - pfn has a dynamic page mapping established by a device driver
- * PFN_SPECIAL - for CONFIG_FS_DAX_LIMITED builds to allow XIP, but not
- *		 get_user_pages
  */
 #define PFN_FLAGS_MASK (((u64) (~PAGE_MASK)) << (BITS_PER_LONG_LONG - PAGE_SHIFT))
-#define PFN_SG_CHAIN (1ULL << (BITS_PER_LONG_LONG - 1))
-#define PFN_SG_LAST (1ULL << (BITS_PER_LONG_LONG - 2))
 #define PFN_DEV (1ULL << (BITS_PER_LONG_LONG - 3))
-#define PFN_MAP (1ULL << (BITS_PER_LONG_LONG - 4))
-#define PFN_SPECIAL (1ULL << (BITS_PER_LONG_LONG - 5))
 
 #define PFN_FLAGS_TRACE \
-	{ PFN_SPECIAL,	"SPECIAL" }, \
-	{ PFN_SG_CHAIN,	"SG_CHAIN" }, \
-	{ PFN_SG_LAST,	"SG_LAST" }, \
-	{ PFN_DEV,	"DEV" }, \
-	{ PFN_MAP,	"MAP" }
+	{ PFN_DEV,	"DEV" }
 
 static inline pfn_t __pfn_to_pfn_t(unsigned long pfn, u64 flags)
 {
@@ -46,7 +33,7 @@ static inline pfn_t phys_to_pfn_t(phys_addr_t addr, u64 flags)
 
 static inline bool pfn_t_has_page(pfn_t pfn)
 {
-	return (pfn.val & PFN_MAP) == PFN_MAP || (pfn.val & PFN_DEV) == 0;
+	return (pfn.val & PFN_DEV) == 0;
 }
 
 static inline unsigned long pfn_t_to_pfn(pfn_t pfn)
@@ -100,7 +87,7 @@ static inline pud_t pfn_t_pud(pfn_t pfn, pgprot_t pgprot)
 #ifdef CONFIG_ARCH_HAS_PTE_DEVMAP
 static inline bool pfn_t_devmap(pfn_t pfn)
 {
-	const u64 flags = PFN_DEV|PFN_MAP;
+	const u64 flags = PFN_DEV;
 
 	return (pfn.val & flags) == flags;
 }
@@ -116,16 +103,4 @@ pmd_t pmd_mkdevmap(pmd_t pmd);
 pud_t pud_mkdevmap(pud_t pud);
 #endif
 #endif /* CONFIG_ARCH_HAS_PTE_DEVMAP */
-
-#ifdef CONFIG_ARCH_HAS_PTE_SPECIAL
-static inline bool pfn_t_special(pfn_t pfn)
-{
-	return (pfn.val & PFN_SPECIAL) == PFN_SPECIAL;
-}
-#else
-static inline bool pfn_t_special(pfn_t pfn)
-{
-	return false;
-}
-#endif /* CONFIG_ARCH_HAS_PTE_SPECIAL */
 #endif /* _LINUX_PFN_T_H_ */
diff --git a/mm/memory.c b/mm/memory.c
index 4919941..cc85f81 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2569,8 +2569,6 @@ static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn, bool mkwrite)
 		return true;
 	if (pfn_t_devmap(pfn))
 		return true;
-	if (pfn_t_special(pfn))
-		return true;
 	if (is_zero_pfn(pfn_t_to_pfn(pfn)))
 		return true;
 	return false;
diff --git a/tools/testing/nvdimm/test/iomap.c b/tools/testing/nvdimm/test/iomap.c
index e431372..ddceb04 100644
--- a/tools/testing/nvdimm/test/iomap.c
+++ b/tools/testing/nvdimm/test/iomap.c
@@ -137,10 +137,6 @@ EXPORT_SYMBOL_GPL(__wrap_devm_memremap_pages);
 
 pfn_t __wrap_phys_to_pfn_t(phys_addr_t addr, unsigned long flags)
 {
-	struct nfit_test_resource *nfit_res = get_nfit_res(addr);
-
-	if (nfit_res)
-		flags &= ~PFN_MAP;
         return phys_to_pfn_t(addr, flags);
 }
 EXPORT_SYMBOL(__wrap_phys_to_pfn_t);
-- 
git-series 0.9.1

[PATCH 02/12] mm: Convert pXd_devmap checks to vma_is_dax

[Alistair Popple]

Currently dax is the only user of pmd and pud mapped ZONE_DEVICE
pages. Therefore page walkers that want to exclude DAX pages can check
pmd_devmap or pud_devmap. However soon dax will no longer set PFN_DEV,
meaning dax pages are mapped as normal pages.

Ensure page walkers that currently use pXd_devmap to skip DAX pages
continue to do so by adding explicit checks of the VMA instead.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 fs/userfaultfd.c | 2 +-
 mm/hmm.c         | 2 +-
 mm/userfaultfd.c | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 22f4bf9..de671d3 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -304,7 +304,7 @@ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx,
 		goto out;
 
 	ret = false;
-	if (!pmd_present(_pmd) || pmd_devmap(_pmd))
+	if (!pmd_present(_pmd) || vma_is_dax(vmf->vma))
 		goto out;
 
 	if (pmd_trans_huge(_pmd)) {
diff --git a/mm/hmm.c b/mm/hmm.c
index 082f7b7..db12c0a 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -429,7 +429,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
 		return hmm_vma_walk_hole(start, end, -1, walk);
 	}
 
-	if (pud_leaf(pud) && pud_devmap(pud)) {
+	if (pud_leaf(pud) && vma_is_dax(walk->vma)) {
 		unsigned long i, npages, pfn;
 		unsigned int required_fault;
 		unsigned long *hmm_pfns;
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index e0db855..133f750 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -1791,7 +1791,7 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
 
 		ptl = pmd_trans_huge_lock(src_pmd, src_vma);
 		if (ptl) {
-			if (pmd_devmap(*src_pmd)) {
+			if (vma_is_dax(src_vma)) {
 				spin_unlock(ptl);
 				err = -ENOENT;
 				break;
-- 
git-series 0.9.1

[PATCH 03/12] mm/pagewalk: Skip dax pages in pagewalk

[Alistair Popple]

Previously dax pages were skipped by the pagewalk code as pud_special() or
vm_normal_page{_pmd}() would be false for DAX pages. Now that dax pages are
refcounted normally that is no longer the case, so add explicit checks to
skip them.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 include/linux/memremap.h | 11 +++++++++++
 mm/pagewalk.c            | 12 ++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 4aa1519..54e8b57 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -198,6 +198,17 @@ static inline bool folio_is_fsdax(const struct folio *folio)
 	return is_fsdax_page(&folio->page);
 }
 
+static inline bool is_devdax_page(const struct page *page)
+{
+	return is_zone_device_page(page) &&
+		page_pgmap(page)->type == MEMORY_DEVICE_GENERIC;
+}
+
+static inline bool folio_is_devdax(const struct folio *folio)
+{
+	return is_devdax_page(&folio->page);
+}
+
 #ifdef CONFIG_ZONE_DEVICE
 void zone_device_page_init(struct page *page);
 void *memremap_pages(struct dev_pagemap *pgmap, int nid);
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index e478777..0dfb9c2 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -884,6 +884,12 @@ struct folio *folio_walk_start(struct folio_walk *fw,
 		 * support PUD mappings in VM_PFNMAP|VM_MIXEDMAP VMAs.
 		 */
 		page = pud_page(pud);
+
+		if (is_devdax_page(page)) {
+			spin_unlock(ptl);
+			goto not_found;
+		}
+
 		goto found;
 	}
 
@@ -911,7 +917,8 @@ struct folio *folio_walk_start(struct folio_walk *fw,
 			goto pte_table;
 		} else if (pmd_present(pmd)) {
 			page = vm_normal_page_pmd(vma, addr, pmd);
-			if (page) {
+			if (page && !is_devdax_page(page) &&
+			    !is_fsdax_page(page)) {
 				goto found;
 			} else if ((flags & FW_ZEROPAGE) &&
 				    is_huge_zero_pmd(pmd)) {
@@ -945,7 +952,8 @@ struct folio *folio_walk_start(struct folio_walk *fw,
 
 	if (pte_present(pte)) {
 		page = vm_normal_page(vma, addr, pte);
-		if (page)
+		if (page && !is_devdax_page(page) &&
+		    !is_fsdax_page(page))
 			goto found;
 		if ((flags & FW_ZEROPAGE) &&
 		    is_zero_pfn(pte_pfn(pte))) {
-- 
git-series 0.9.1

[PATCH 04/12] mm: Convert vmf_insert_mixed() from using pte_devmap to pte_special

[Alistair Popple]

DAX no longer requires device PTEs as it always has a ZONE_DEVICE page
associated with the PTE that can be reference counted normally. Other users
of pte_devmap are drivers that set PFN_DEV when calling vmf_insert_mixed()
which ensures vm_normal_page() returns NULL for these entries.

There is no reason to distinguish these pte_devmap users so in order to
free up a PTE bit use pte_special instead for entries created with
vmf_insert_mixed(). This will ensure vm_normal_page() will continue to
return NULL for these pages.

Architectures that don't support pte_special also don't support pte_devmap
so those will continue to rely on pfn_valid() to determine if the page can
be mapped.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 mm/hmm.c    |  3 ---
 mm/memory.c | 20 ++------------------
 mm/vmscan.c |  2 +-
 3 files changed, 3 insertions(+), 22 deletions(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index db12c0a..9e43008 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -292,13 +292,10 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
 		goto fault;
 
 	/*
-	 * Bypass devmap pte such as DAX page when all pfn requested
-	 * flags(pfn_req_flags) are fulfilled.
 	 * Since each architecture defines a struct page for the zero page, just
 	 * fall through and treat it like a normal page.
 	 */
 	if (!vm_normal_page(walk->vma, addr, pte) &&
-	    !pte_devmap(pte) &&
 	    !is_zero_pfn(pte_pfn(pte))) {
 		if (hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0)) {
 			pte_unmap(ptep);
diff --git a/mm/memory.c b/mm/memory.c
index cc85f81..1a0c813 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -586,16 +586,6 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
 			return NULL;
 		if (is_zero_pfn(pfn))
 			return NULL;
-		if (pte_devmap(pte))
-		/*
-		 * NOTE: New users of ZONE_DEVICE will not set pte_devmap()
-		 * and will have refcounts incremented on their struct pages
-		 * when they are inserted into PTEs, thus they are safe to
-		 * return here. Legacy ZONE_DEVICE pages that set pte_devmap()
-		 * do not have refcounts. Example of legacy ZONE_DEVICE is
-		 * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers.
-		 */
-			return NULL;
 
 		print_bad_pte(vma, addr, pte, NULL);
 		return NULL;
@@ -2453,10 +2443,7 @@ static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 	}
 
 	/* Ok, finally just insert the thing.. */
-	if (pfn_t_devmap(pfn))
-		entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
-	else
-		entry = pte_mkspecial(pfn_t_pte(pfn, prot));
+	entry = pte_mkspecial(pfn_t_pte(pfn, prot));
 
 	if (mkwrite) {
 		entry = pte_mkyoung(entry);
@@ -2567,8 +2554,6 @@ static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn, bool mkwrite)
 	/* these checks mirror the abort conditions in vm_normal_page */
 	if (vma->vm_flags & VM_MIXEDMAP)
 		return true;
-	if (pfn_t_devmap(pfn))
-		return true;
 	if (is_zero_pfn(pfn_t_to_pfn(pfn)))
 		return true;
 	return false;
@@ -2598,8 +2583,7 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
 	 * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
 	 * without pte special, it would there be refcounted as a normal page.
 	 */
-	if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
-	    !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
+	if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pfn_t_valid(pfn)) {
 		struct page *page;
 
 		/*
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 3783e45..61e6c44 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3401,7 +3401,7 @@ static unsigned long get_pte_pfn(pte_t pte, struct vm_area_struct *vma, unsigned
 	if (!pte_present(pte) || is_zero_pfn(pfn))
 		return -1;
 
-	if (WARN_ON_ONCE(pte_devmap(pte) || pte_special(pte)))
+	if (WARN_ON_ONCE(pte_special(pte)))
 		return -1;
 
 	if (!pte_young(pte) && !mm_has_notifiers(vma->vm_mm))
-- 
git-series 0.9.1

[PATCH 05/12] mm: Remove remaining uses of PFN_DEV

[Alistair Popple]

PFN_DEV was used by callers of dax_direct_access() to figure out if the
returned PFN is associated with a page using pfn_t_has_page() or
not. However all DAX PFNs now require an assoicated ZONE_DEVICE page so can
assume a page exists.

Other users of PFN_DEV were setting it before calling
vmf_insert_mixed(). This is unnecessary as it is no longer checked, instead
relying on pfn_valid() to determine if there is an associated page or not.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 drivers/gpu/drm/gma500/fbdev.c     |  2 +-
 drivers/gpu/drm/omapdrm/omap_gem.c |  5 ++---
 drivers/s390/block/dcssblk.c       |  3 +--
 drivers/vfio/pci/vfio_pci_core.c   |  6 ++----
 fs/cramfs/inode.c                  |  2 +-
 include/linux/pfn_t.h              | 25 ++-----------------------
 mm/memory.c                        |  4 ++--
 7 files changed, 11 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/gma500/fbdev.c b/drivers/gpu/drm/gma500/fbdev.c
index 8edefea..109efdc 100644
--- a/drivers/gpu/drm/gma500/fbdev.c
+++ b/drivers/gpu/drm/gma500/fbdev.c
@@ -33,7 +33,7 @@ static vm_fault_t psb_fbdev_vm_fault(struct vm_fault *vmf)
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 
 	for (i = 0; i < page_num; ++i) {
-		err = vmf_insert_mixed(vma, address, __pfn_to_pfn_t(pfn, PFN_DEV));
+		err = vmf_insert_mixed(vma, address, __pfn_to_pfn_t(pfn, 0));
 		if (unlikely(err & VM_FAULT_ERROR))
 			break;
 		address += PAGE_SIZE;
diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index b9c67e4..9df05b2 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -371,8 +371,7 @@ static vm_fault_t omap_gem_fault_1d(struct drm_gem_object *obj,
 	VERB("Inserting %p pfn %lx, pa %lx", (void *)vmf->address,
 			pfn, pfn << PAGE_SHIFT);
 
-	return vmf_insert_mixed(vma, vmf->address,
-			__pfn_to_pfn_t(pfn, PFN_DEV));
+	return vmf_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, 0));
 }
 
 /* Special handling for the case of faulting in 2d tiled buffers */
@@ -468,7 +467,7 @@ static vm_fault_t omap_gem_fault_2d(struct drm_gem_object *obj,
 
 	for (i = n; i > 0; i--) {
 		ret = vmf_insert_mixed(vma,
-			vaddr, __pfn_to_pfn_t(pfn, PFN_DEV));
+			vaddr, __pfn_to_pfn_t(pfn, 0));
 		if (ret & VM_FAULT_ERROR)
 			break;
 		pfn += priv->usergart[fmt].stride_pfn;
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 7248e54..02d7a21 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -923,8 +923,7 @@ __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 	if (kaddr)
 		*kaddr = __va(dev_info->start + offset);
 	if (pfn)
-		*pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
-				      PFN_DEV);
+		*pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), 0);
 
 	return (dev_sz - offset) / PAGE_SIZE;
 }
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 6328c3a..3f2ad5f 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -1669,14 +1669,12 @@ static vm_fault_t vfio_pci_mmap_huge_fault(struct vm_fault *vmf,
 		break;
 #ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
 	case PMD_ORDER:
-		ret = vmf_insert_pfn_pmd(vmf,
-					 __pfn_to_pfn_t(pfn, PFN_DEV), false);
+		ret = vmf_insert_pfn_pmd(vmf, __pfn_to_pfn_t(pfn, 0), false);
 		break;
 #endif
 #ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
 	case PUD_ORDER:
-		ret = vmf_insert_pfn_pud(vmf,
-					 __pfn_to_pfn_t(pfn, PFN_DEV), false);
+		ret = vmf_insert_pfn_pud(vmf, __pfn_to_pfn_t(pfn, 0), false);
 		break;
 #endif
 	default:
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index b84d174..820a664 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -412,7 +412,7 @@ static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
 		for (i = 0; i < pages && !ret; i++) {
 			vm_fault_t vmf;
 			unsigned long off = i * PAGE_SIZE;
-			pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV);
+			pfn_t pfn = phys_to_pfn_t(address + off, 0);
 			vmf = vmf_insert_mixed(vma, vma->vm_start + off, pfn);
 			if (vmf & VM_FAULT_ERROR)
 				ret = vm_fault_to_errno(vmf, 0);
diff --git a/include/linux/pfn_t.h b/include/linux/pfn_t.h
index 46afa12..be8c174 100644
--- a/include/linux/pfn_t.h
+++ b/include/linux/pfn_t.h
@@ -8,10 +8,8 @@
  * PFN_DEV - pfn is not covered by system memmap by default
  */
 #define PFN_FLAGS_MASK (((u64) (~PAGE_MASK)) << (BITS_PER_LONG_LONG - PAGE_SHIFT))
-#define PFN_DEV (1ULL << (BITS_PER_LONG_LONG - 3))
 
-#define PFN_FLAGS_TRACE \
-	{ PFN_DEV,	"DEV" }
+#define PFN_FLAGS_TRACE { }
 
 static inline pfn_t __pfn_to_pfn_t(unsigned long pfn, u64 flags)
 {
@@ -33,7 +31,7 @@ static inline pfn_t phys_to_pfn_t(phys_addr_t addr, u64 flags)
 
 static inline bool pfn_t_has_page(pfn_t pfn)
 {
-	return (pfn.val & PFN_DEV) == 0;
+	return true;
 }
 
 static inline unsigned long pfn_t_to_pfn(pfn_t pfn)
@@ -84,23 +82,4 @@ static inline pud_t pfn_t_pud(pfn_t pfn, pgprot_t pgprot)
 #endif
 #endif
 
-#ifdef CONFIG_ARCH_HAS_PTE_DEVMAP
-static inline bool pfn_t_devmap(pfn_t pfn)
-{
-	const u64 flags = PFN_DEV;
-
-	return (pfn.val & flags) == flags;
-}
-#else
-static inline bool pfn_t_devmap(pfn_t pfn)
-{
-	return false;
-}
-pte_t pte_mkdevmap(pte_t pte);
-pmd_t pmd_mkdevmap(pmd_t pmd);
-#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
-	defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
-pud_t pud_mkdevmap(pud_t pud);
-#endif
-#endif /* CONFIG_ARCH_HAS_PTE_DEVMAP */
 #endif /* _LINUX_PFN_T_H_ */
diff --git a/mm/memory.c b/mm/memory.c
index 1a0c813..7a9aaae 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2512,9 +2512,9 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 	if (!pfn_modify_allowed(pfn, pgprot))
 		return VM_FAULT_SIGBUS;
 
-	track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
+	track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, 0));
 
-	return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
+	return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, 0), pgprot,
 			false);
 }
 EXPORT_SYMBOL(vmf_insert_pfn_prot);
-- 
git-series 0.9.1

[PATCH 06/12] mm/gup: Remove pXX_devmap usage from get_user_pages()

[Alistair Popple]

GUP uses pXX_devmap() calls to see if it needs to a get a reference on
the associated pgmap data structure to ensure the pages won't go
away. However it's a driver responsibility to ensure that if pages are
mapped (ie. discoverable by GUP) that they are not offlined or removed
from the memmap so there is no need to hold a reference on the pgmap
data structure to ensure this.

Furthermore mappings with PFN_DEV are no longer created, hence this
effectively dead code anyway so can be removed.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 include/linux/huge_mm.h |   3 +-
 mm/gup.c                | 162 +----------------------------------------
 mm/huge_memory.c        |  40 +----------
 3 files changed, 5 insertions(+), 200 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index e893d54..c0b01d1 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -474,9 +474,6 @@ static inline bool folio_test_pmd_mappable(struct folio *folio)
 	return folio_order(folio) >= HPAGE_PMD_ORDER;
 }
 
-struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
-		pmd_t *pmd, int flags, struct dev_pagemap **pgmap);
-
 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf);
 
 extern struct folio *huge_zero_folio;
diff --git a/mm/gup.c b/mm/gup.c
index 84461d3..1a959f2 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -678,31 +678,9 @@ static struct page *follow_huge_pud(struct vm_area_struct *vma,
 		return NULL;
 
 	pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
-
-	if (IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) &&
-	    pud_devmap(pud)) {
-		/*
-		 * device mapped pages can only be returned if the caller
-		 * will manage the page reference count.
-		 *
-		 * At least one of FOLL_GET | FOLL_PIN must be set, so
-		 * assert that here:
-		 */
-		if (!(flags & (FOLL_GET | FOLL_PIN)))
-			return ERR_PTR(-EEXIST);
-
-		if (flags & FOLL_TOUCH)
-			touch_pud(vma, addr, pudp, flags & FOLL_WRITE);
-
-		ctx->pgmap = get_dev_pagemap(pfn, ctx->pgmap);
-		if (!ctx->pgmap)
-			return ERR_PTR(-EFAULT);
-	}
-
 	page = pfn_to_page(pfn);
 
-	if (!pud_devmap(pud) && !pud_write(pud) &&
-	    gup_must_unshare(vma, flags, page))
+	if (!pud_write(pud) && gup_must_unshare(vma, flags, page))
 		return ERR_PTR(-EMLINK);
 
 	ret = try_grab_folio(page_folio(page), 1, flags);
@@ -861,8 +839,7 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
 	page = vm_normal_page(vma, address, pte);
 
 	/*
-	 * We only care about anon pages in can_follow_write_pte() and don't
-	 * have to worry about pte_devmap() because they are never anon.
+	 * We only care about anon pages in can_follow_write_pte().
 	 */
 	if ((flags & FOLL_WRITE) &&
 	    !can_follow_write_pte(pte, page, vma, flags)) {
@@ -870,18 +847,7 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
 		goto out;
 	}
 
-	if (!page && pte_devmap(pte) && (flags & (FOLL_GET | FOLL_PIN))) {
-		/*
-		 * Only return device mapping pages in the FOLL_GET or FOLL_PIN
-		 * case since they are only valid while holding the pgmap
-		 * reference.
-		 */
-		*pgmap = get_dev_pagemap(pte_pfn(pte), *pgmap);
-		if (*pgmap)
-			page = pte_page(pte);
-		else
-			goto no_page;
-	} else if (unlikely(!page)) {
+	if (unlikely(!page)) {
 		if (flags & FOLL_DUMP) {
 			/* Avoid special (like zero) pages in core dumps */
 			page = ERR_PTR(-EFAULT);
@@ -963,14 +929,6 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
 		return no_page_table(vma, flags, address);
 	if (!pmd_present(pmdval))
 		return no_page_table(vma, flags, address);
-	if (pmd_devmap(pmdval)) {
-		ptl = pmd_lock(mm, pmd);
-		page = follow_devmap_pmd(vma, address, pmd, flags, &ctx->pgmap);
-		spin_unlock(ptl);
-		if (page)
-			return page;
-		return no_page_table(vma, flags, address);
-	}
 	if (likely(!pmd_leaf(pmdval)))
 		return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
 
@@ -2889,7 +2847,7 @@ static int gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
 		int *nr)
 {
 	struct dev_pagemap *pgmap = NULL;
-	int nr_start = *nr, ret = 0;
+	int ret = 0;
 	pte_t *ptep, *ptem;
 
 	ptem = ptep = pte_offset_map(&pmd, addr);
@@ -2913,16 +2871,7 @@ static int gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
 		if (!pte_access_permitted(pte, flags & FOLL_WRITE))
 			goto pte_unmap;
 
-		if (pte_devmap(pte)) {
-			if (unlikely(flags & FOLL_LONGTERM))
-				goto pte_unmap;
-
-			pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);
-			if (unlikely(!pgmap)) {
-				gup_fast_undo_dev_pagemap(nr, nr_start, flags, pages);
-				goto pte_unmap;
-			}
-		} else if (pte_special(pte))
+		if (pte_special(pte))
 			goto pte_unmap;
 
 		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
@@ -2993,91 +2942,6 @@ static int gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
 }
 #endif /* CONFIG_ARCH_HAS_PTE_SPECIAL */
 
-#if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
-static int gup_fast_devmap_leaf(unsigned long pfn, unsigned long addr,
-	unsigned long end, unsigned int flags, struct page **pages, int *nr)
-{
-	int nr_start = *nr;
-	struct dev_pagemap *pgmap = NULL;
-
-	do {
-		struct folio *folio;
-		struct page *page = pfn_to_page(pfn);
-
-		pgmap = get_dev_pagemap(pfn, pgmap);
-		if (unlikely(!pgmap)) {
-			gup_fast_undo_dev_pagemap(nr, nr_start, flags, pages);
-			break;
-		}
-
-		folio = try_grab_folio_fast(page, 1, flags);
-		if (!folio) {
-			gup_fast_undo_dev_pagemap(nr, nr_start, flags, pages);
-			break;
-		}
-		folio_set_referenced(folio);
-		pages[*nr] = page;
-		(*nr)++;
-		pfn++;
-	} while (addr += PAGE_SIZE, addr != end);
-
-	put_dev_pagemap(pgmap);
-	return addr == end;
-}
-
-static int gup_fast_devmap_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr,
-		unsigned long end, unsigned int flags, struct page **pages,
-		int *nr)
-{
-	unsigned long fault_pfn;
-	int nr_start = *nr;
-
-	fault_pfn = pmd_pfn(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	if (!gup_fast_devmap_leaf(fault_pfn, addr, end, flags, pages, nr))
-		return 0;
-
-	if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) {
-		gup_fast_undo_dev_pagemap(nr, nr_start, flags, pages);
-		return 0;
-	}
-	return 1;
-}
-
-static int gup_fast_devmap_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr,
-		unsigned long end, unsigned int flags, struct page **pages,
-		int *nr)
-{
-	unsigned long fault_pfn;
-	int nr_start = *nr;
-
-	fault_pfn = pud_pfn(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	if (!gup_fast_devmap_leaf(fault_pfn, addr, end, flags, pages, nr))
-		return 0;
-
-	if (unlikely(pud_val(orig) != pud_val(*pudp))) {
-		gup_fast_undo_dev_pagemap(nr, nr_start, flags, pages);
-		return 0;
-	}
-	return 1;
-}
-#else
-static int gup_fast_devmap_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr,
-		unsigned long end, unsigned int flags, struct page **pages,
-		int *nr)
-{
-	BUILD_BUG();
-	return 0;
-}
-
-static int gup_fast_devmap_pud_leaf(pud_t pud, pud_t *pudp, unsigned long addr,
-		unsigned long end, unsigned int flags, struct page **pages,
-		int *nr)
-{
-	BUILD_BUG();
-	return 0;
-}
-#endif
-
 static int gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 		unsigned long end, unsigned int flags, struct page **pages,
 		int *nr)
@@ -3092,13 +2956,6 @@ static int gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 	if (pmd_special(orig))
 		return 0;
 
-	if (pmd_devmap(orig)) {
-		if (unlikely(flags & FOLL_LONGTERM))
-			return 0;
-		return gup_fast_devmap_pmd_leaf(orig, pmdp, addr, end, flags,
-					        pages, nr);
-	}
-
 	page = pmd_page(orig);
 	refs = record_subpages(page, PMD_SIZE, addr, end, pages + *nr);
 
@@ -3139,13 +2996,6 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr,
 	if (pud_special(orig))
 		return 0;
 
-	if (pud_devmap(orig)) {
-		if (unlikely(flags & FOLL_LONGTERM))
-			return 0;
-		return gup_fast_devmap_pud_leaf(orig, pudp, addr, end, flags,
-					        pages, nr);
-	}
-
 	page = pud_page(orig);
 	refs = record_subpages(page, PUD_SIZE, addr, end, pages + *nr);
 
@@ -3184,8 +3034,6 @@ static int gup_fast_pgd_leaf(pgd_t orig, pgd_t *pgdp, unsigned long addr,
 	if (!pgd_access_permitted(orig, flags & FOLL_WRITE))
 		return 0;
 
-	BUILD_BUG_ON(pgd_devmap(orig));
-
 	page = pgd_page(orig);
 	refs = record_subpages(page, PGDIR_SIZE, addr, end, pages + *nr);
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 47d76d0..8d9d706 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1646,46 +1646,6 @@ void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
 		update_mmu_cache_pmd(vma, addr, pmd);
 }
 
-struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
-		pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
-{
-	unsigned long pfn = pmd_pfn(*pmd);
-	struct mm_struct *mm = vma->vm_mm;
-	struct page *page;
-	int ret;
-
-	assert_spin_locked(pmd_lockptr(mm, pmd));
-
-	if (flags & FOLL_WRITE && !pmd_write(*pmd))
-		return NULL;
-
-	if (pmd_present(*pmd) && pmd_devmap(*pmd))
-		/* pass */;
-	else
-		return NULL;
-
-	if (flags & FOLL_TOUCH)
-		touch_pmd(vma, addr, pmd, flags & FOLL_WRITE);
-
-	/*
-	 * device mapped pages can only be returned if the
-	 * caller will manage the page reference count.
-	 */
-	if (!(flags & (FOLL_GET | FOLL_PIN)))
-		return ERR_PTR(-EEXIST);
-
-	pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
-	*pgmap = get_dev_pagemap(pfn, *pgmap);
-	if (!*pgmap)
-		return ERR_PTR(-EFAULT);
-	page = pfn_to_page(pfn);
-	ret = try_grab_folio(page_folio(page), 1, flags);
-	if (ret)
-		page = ERR_PTR(ret);
-
-	return page;
-}
-
 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		  pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
 		  struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
-- 
git-series 0.9.1

[PATCH 07/12] mm: Remove redundant pXd_devmap calls

[Alistair Popple]

DAX was the only thing that created pmd_devmap and pud_devmap entries
however it no longer does as DAX pages are now refcounted normally and
pXd_trans_huge() returns true for those. Therefore checking both pXd_devmap
and pXd_trans_huge() is redundant and the former can be removed without
changing behaviour as it will always be false.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 fs/dax.c                   |  5 ++---
 include/linux/huge_mm.h    | 10 ++++------
 include/linux/pgtable.h    |  2 +-
 mm/hmm.c                   |  4 ++--
 mm/huge_memory.c           | 30 +++++++++---------------------
 mm/mapping_dirty_helpers.c |  4 ++--
 mm/memory.c                | 15 ++++++---------
 mm/migrate_device.c        |  2 +-
 mm/mprotect.c              |  2 +-
 mm/mremap.c                |  5 ++---
 mm/page_vma_mapped.c       |  5 ++---
 mm/pagewalk.c              |  8 +++-----
 mm/pgtable-generic.c       |  7 +++----
 mm/userfaultfd.c           |  4 ++--
 mm/vmscan.c                |  3 ---
 15 files changed, 40 insertions(+), 66 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 6763034..206dbd0 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1938,7 +1938,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	 * the PTE we need to set up.  If so just return and the fault will be
 	 * retried.
 	 */
-	if (pmd_trans_huge(*vmf->pmd) || pmd_devmap(*vmf->pmd)) {
+	if (pmd_trans_huge(*vmf->pmd)) {
 		ret = VM_FAULT_NOPAGE;
 		goto unlock_entry;
 	}
@@ -2061,8 +2061,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	 * the PMD we need to set up.  If so just return and the fault will be
 	 * retried.
 	 */
-	if (!pmd_none(*vmf->pmd) && !pmd_trans_huge(*vmf->pmd) &&
-			!pmd_devmap(*vmf->pmd)) {
+	if (!pmd_none(*vmf->pmd) && !pmd_trans_huge(*vmf->pmd)) {
 		ret = 0;
 		goto unlock_entry;
 	}
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index c0b01d1..374daa8 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -400,8 +400,7 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 #define split_huge_pmd(__vma, __pmd, __address)				\
 	do {								\
 		pmd_t *____pmd = (__pmd);				\
-		if (is_swap_pmd(*____pmd) || pmd_trans_huge(*____pmd)	\
-					|| pmd_devmap(*____pmd))	\
+		if (is_swap_pmd(*____pmd) || pmd_trans_huge(*____pmd))	\
 			__split_huge_pmd(__vma, __pmd, __address,	\
 						false, NULL);		\
 	}  while (0)
@@ -427,8 +426,7 @@ change_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
 #define split_huge_pud(__vma, __pud, __address)				\
 	do {								\
 		pud_t *____pud = (__pud);				\
-		if (pud_trans_huge(*____pud)				\
-					|| pud_devmap(*____pud))	\
+		if (pud_trans_huge(*____pud))				\
 			__split_huge_pud(__vma, __pud, __address);	\
 	}  while (0)
 
@@ -451,7 +449,7 @@ static inline int is_swap_pmd(pmd_t pmd)
 static inline spinlock_t *pmd_trans_huge_lock(pmd_t *pmd,
 		struct vm_area_struct *vma)
 {
-	if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd))
+	if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd))
 		return __pmd_trans_huge_lock(pmd, vma);
 	else
 		return NULL;
@@ -459,7 +457,7 @@ static inline spinlock_t *pmd_trans_huge_lock(pmd_t *pmd,
 static inline spinlock_t *pud_trans_huge_lock(pud_t *pud,
 		struct vm_area_struct *vma)
 {
-	if (pud_trans_huge(*pud) || pud_devmap(*pud))
+	if (pud_trans_huge(*pud))
 		return __pud_trans_huge_lock(pud, vma);
 	else
 		return NULL;
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index b50447e..a6f9573 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1656,7 +1656,7 @@ static inline int pud_trans_unstable(pud_t *pud)
 	defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
 	pud_t pudval = READ_ONCE(*pud);
 
-	if (pud_none(pudval) || pud_trans_huge(pudval) || pud_devmap(pudval))
+	if (pud_none(pudval) || pud_trans_huge(pudval))
 		return 1;
 	if (unlikely(pud_bad(pudval))) {
 		pud_clear_bad(pud);
diff --git a/mm/hmm.c b/mm/hmm.c
index 9e43008..5037f98 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -348,7 +348,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
 		return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
 	}
 
-	if (pmd_devmap(pmd) || pmd_trans_huge(pmd)) {
+	if (pmd_trans_huge(pmd)) {
 		/*
 		 * No need to take pmd_lock here, even if some other thread
 		 * is splitting the huge pmd we will get that event through
@@ -359,7 +359,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
 		 * values.
 		 */
 		pmd = pmdp_get_lockless(pmdp);
-		if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd))
+		if (!pmd_trans_huge(pmd))
 			goto again;
 
 		return hmm_vma_handle_pmd(walk, addr, end, hmm_pfns, pmd);
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 8d9d706..31b4110 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1398,10 +1398,7 @@ static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 	}
 
 	entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
-	if (pfn_t_devmap(pfn))
-		entry = pmd_mkdevmap(entry);
-	else
-		entry = pmd_mkspecial(entry);
+	entry = pmd_mkspecial(entry);
 	if (write) {
 		entry = pmd_mkyoung(pmd_mkdirty(entry));
 		entry = maybe_pmd_mkwrite(entry, vma);
@@ -1441,8 +1438,6 @@ vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
 	 * but we need to be consistent with PTEs and architectures that
 	 * can't support a 'special' bit.
 	 */
-	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
-			!pfn_t_devmap(pfn));
 	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
 						(VM_PFNMAP|VM_MIXEDMAP));
 	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
@@ -1535,10 +1530,7 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
 	}
 
 	entry = pud_mkhuge(pfn_t_pud(pfn, prot));
-	if (pfn_t_devmap(pfn))
-		entry = pud_mkdevmap(entry);
-	else
-		entry = pud_mkspecial(entry);
+	entry = pud_mkspecial(entry);
 	if (write) {
 		entry = pud_mkyoung(pud_mkdirty(entry));
 		entry = maybe_pud_mkwrite(entry, vma);
@@ -1569,8 +1561,6 @@ vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
 	 * but we need to be consistent with PTEs and architectures that
 	 * can't support a 'special' bit.
 	 */
-	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
-			!pfn_t_devmap(pfn));
 	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
 						(VM_PFNMAP|VM_MIXEDMAP));
 	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
@@ -1797,7 +1787,7 @@ int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 
 	ret = -EAGAIN;
 	pud = *src_pud;
-	if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
+	if (unlikely(!pud_trans_huge(pud)))
 		goto out_unlock;
 
 	/*
@@ -2651,8 +2641,7 @@ spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
 {
 	spinlock_t *ptl;
 	ptl = pmd_lock(vma->vm_mm, pmd);
-	if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
-			pmd_devmap(*pmd)))
+	if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd)))
 		return ptl;
 	spin_unlock(ptl);
 	return NULL;
@@ -2669,7 +2658,7 @@ spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
 	spinlock_t *ptl;
 
 	ptl = pud_lock(vma->vm_mm, pud);
-	if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
+	if (likely(pud_trans_huge(*pud)))
 		return ptl;
 	spin_unlock(ptl);
 	return NULL;
@@ -2721,7 +2710,7 @@ static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
 	VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
 	VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
 	VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
-	VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
+	VM_BUG_ON(!pud_trans_huge(*pud));
 
 	count_vm_event(THP_SPLIT_PUD);
 
@@ -2754,7 +2743,7 @@ void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
 				(address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
 	mmu_notifier_invalidate_range_start(&range);
 	ptl = pud_lock(vma->vm_mm, pud);
-	if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
+	if (unlikely(!pud_trans_huge(*pud)))
 		goto out;
 	__split_huge_pud_locked(vma, pud, range.start);
 
@@ -2827,8 +2816,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 	VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
 	VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
 	VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
-	VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
-				&& !pmd_devmap(*pmd));
+	VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd));
 
 	count_vm_event(THP_SPLIT_PMD);
 
@@ -3047,7 +3035,7 @@ void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long address,
 	 * require a folio to check the PMD against. Otherwise, there
 	 * is a risk of replacing the wrong folio.
 	 */
-	if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || pmd_migration) {
+	if (pmd_trans_huge(*pmd) || pmd_migration) {
 		/*
 		 * Do not apply pmd_folio() to a migration entry; and folio lock
 		 * guarantees that it must be of the wrong folio anyway.
diff --git a/mm/mapping_dirty_helpers.c b/mm/mapping_dirty_helpers.c
index 2f8829b..208b428 100644
--- a/mm/mapping_dirty_helpers.c
+++ b/mm/mapping_dirty_helpers.c
@@ -129,7 +129,7 @@ static int wp_clean_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long end,
 	pmd_t pmdval = pmdp_get_lockless(pmd);
 
 	/* Do not split a huge pmd, present or migrated */
-	if (pmd_trans_huge(pmdval) || pmd_devmap(pmdval)) {
+	if (pmd_trans_huge(pmdval)) {
 		WARN_ON(pmd_write(pmdval) || pmd_dirty(pmdval));
 		walk->action = ACTION_CONTINUE;
 	}
@@ -152,7 +152,7 @@ static int wp_clean_pud_entry(pud_t *pud, unsigned long addr, unsigned long end,
 	pud_t pudval = READ_ONCE(*pud);
 
 	/* Do not split a huge pud */
-	if (pud_trans_huge(pudval) || pud_devmap(pudval)) {
+	if (pud_trans_huge(pudval)) {
 		WARN_ON(pud_write(pudval) || pud_dirty(pudval));
 		walk->action = ACTION_CONTINUE;
 	}
diff --git a/mm/memory.c b/mm/memory.c
index 7a9aaae..6b03771 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -663,8 +663,6 @@ struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
 		}
 	}
 
-	if (pmd_devmap(pmd))
-		return NULL;
 	if (is_huge_zero_pmd(pmd))
 		return NULL;
 	if (unlikely(pfn > highest_memmap_pfn))
@@ -1228,8 +1226,7 @@ copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
 	src_pmd = pmd_offset(src_pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
-		if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
-			|| pmd_devmap(*src_pmd)) {
+		if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)) {
 			int err;
 			VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
 			err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd,
@@ -1265,7 +1262,7 @@ copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
 	src_pud = pud_offset(src_p4d, addr);
 	do {
 		next = pud_addr_end(addr, end);
-		if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
+		if (pud_trans_huge(*src_pud)) {
 			int err;
 
 			VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma);
@@ -1787,7 +1784,7 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
-		if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
+		if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd)) {
 			if (next - addr != HPAGE_PMD_SIZE)
 				__split_huge_pmd(vma, pmd, addr, false, NULL);
 			else if (zap_huge_pmd(tlb, vma, pmd, addr)) {
@@ -1829,7 +1826,7 @@ static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
 	pud = pud_offset(p4d, addr);
 	do {
 		next = pud_addr_end(addr, end);
-		if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
+		if (pud_trans_huge(*pud)) {
 			if (next - addr != HPAGE_PUD_SIZE) {
 				mmap_assert_locked(tlb->mm);
 				split_huge_pud(vma, pud, addr);
@@ -6062,7 +6059,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
 		pud_t orig_pud = *vmf.pud;
 
 		barrier();
-		if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
+		if (pud_trans_huge(orig_pud)) {
 
 			/*
 			 * TODO once we support anonymous PUDs: NUMA case and
@@ -6103,7 +6100,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
 				pmd_migration_entry_wait(mm, vmf.pmd);
 			return 0;
 		}
-		if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) {
+		if (pmd_trans_huge(vmf.orig_pmd)) {
 			if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
 				return do_huge_pmd_numa_page(&vmf);
 
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 3158afe..e05e14d 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -615,7 +615,7 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
 	pmdp = pmd_alloc(mm, pudp, addr);
 	if (!pmdp)
 		goto abort;
-	if (pmd_trans_huge(*pmdp) || pmd_devmap(*pmdp))
+	if (pmd_trans_huge(*pmdp))
 		goto abort;
 	if (pte_alloc(mm, pmdp))
 		goto abort;
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 62c1f79..dbf49c8 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -376,7 +376,7 @@ static inline long change_pmd_range(struct mmu_gather *tlb,
 			goto next;
 
 		_pmd = pmdp_get_lockless(pmd);
-		if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) {
+		if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd)) {
 			if ((next - addr != HPAGE_PMD_SIZE) ||
 			    pgtable_split_needed(vma, cp_flags)) {
 				__split_huge_pmd(vma, pmd, addr, false, NULL);
diff --git a/mm/mremap.c b/mm/mremap.c
index 7db9da6..bcebfda 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -792,7 +792,7 @@ unsigned long move_page_tables(struct pagetable_move_control *pmc)
 		new_pud = alloc_new_pud(mm, pmc->new_addr);
 		if (!new_pud)
 			break;
-		if (pud_trans_huge(*old_pud) || pud_devmap(*old_pud)) {
+		if (pud_trans_huge(*old_pud)) {
 			if (extent == HPAGE_PUD_SIZE) {
 				move_pgt_entry(pmc, HPAGE_PUD, old_pud, new_pud);
 				/* We ignore and continue on error? */
@@ -811,8 +811,7 @@ unsigned long move_page_tables(struct pagetable_move_control *pmc)
 		if (!new_pmd)
 			break;
 again:
-		if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd) ||
-		    pmd_devmap(*old_pmd)) {
+		if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd)) {
 			if (extent == HPAGE_PMD_SIZE &&
 			    move_pgt_entry(pmc, HPAGE_PMD, old_pmd, new_pmd))
 				continue;
diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index e463c3b..e981a1a 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -246,8 +246,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 		 */
 		pmde = pmdp_get_lockless(pvmw->pmd);
 
-		if (pmd_trans_huge(pmde) || is_pmd_migration_entry(pmde) ||
-		    (pmd_present(pmde) && pmd_devmap(pmde))) {
+		if (pmd_trans_huge(pmde) || is_pmd_migration_entry(pmde)) {
 			pvmw->ptl = pmd_lock(mm, pvmw->pmd);
 			pmde = *pvmw->pmd;
 			if (!pmd_present(pmde)) {
@@ -262,7 +261,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 					return not_found(pvmw);
 				return true;
 			}
-			if (likely(pmd_trans_huge(pmde) || pmd_devmap(pmde))) {
+			if (likely(pmd_trans_huge(pmde))) {
 				if (pvmw->flags & PVMW_MIGRATION)
 					return not_found(pvmw);
 				if (!check_pmd(pmd_pfn(pmde), pvmw))
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 0dfb9c2..cca170f 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -143,8 +143,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 			 * We are ONLY installing, so avoid unnecessarily
 			 * splitting a present huge page.
 			 */
-			if (pmd_present(*pmd) &&
-			    (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)))
+			if (pmd_present(*pmd) && pmd_trans_huge(*pmd))
 				continue;
 		}
 
@@ -210,8 +209,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
 			 * We are ONLY installing, so avoid unnecessarily
 			 * splitting a present huge page.
 			 */
-			if (pud_present(*pud) &&
-			    (pud_trans_huge(*pud) || pud_devmap(*pud)))
+			if (pud_present(*pud) && pud_trans_huge(*pud))
 				continue;
 		}
 
@@ -872,7 +870,7 @@ struct folio *folio_walk_start(struct folio_walk *fw,
 		 * TODO: FW_MIGRATION support for PUD migration entries
 		 * once there are relevant users.
 		 */
-		if (!pud_present(pud) || pud_devmap(pud) || pud_special(pud)) {
+		if (!pud_present(pud) || pud_special(pud)) {
 			spin_unlock(ptl);
 			goto not_found;
 		} else if (!pud_leaf(pud)) {
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 5a882f2..567e2d0 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -139,8 +139,7 @@ pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
 {
 	pmd_t pmd;
 	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
-	VM_BUG_ON(pmd_present(*pmdp) && !pmd_trans_huge(*pmdp) &&
-			   !pmd_devmap(*pmdp));
+	VM_BUG_ON(pmd_present(*pmdp) && !pmd_trans_huge(*pmdp));
 	pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
 	flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 	return pmd;
@@ -153,7 +152,7 @@ pud_t pudp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
 	pud_t pud;
 
 	VM_BUG_ON(address & ~HPAGE_PUD_MASK);
-	VM_BUG_ON(!pud_trans_huge(*pudp) && !pud_devmap(*pudp));
+	VM_BUG_ON(!pud_trans_huge(*pudp));
 	pud = pudp_huge_get_and_clear(vma->vm_mm, address, pudp);
 	flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
 	return pud;
@@ -293,7 +292,7 @@ pte_t *___pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp)
 		*pmdvalp = pmdval;
 	if (unlikely(pmd_none(pmdval) || is_pmd_migration_entry(pmdval)))
 		goto nomap;
-	if (unlikely(pmd_trans_huge(pmdval) || pmd_devmap(pmdval)))
+	if (unlikely(pmd_trans_huge(pmdval)))
 		goto nomap;
 	if (unlikely(pmd_bad(pmdval))) {
 		pmd_clear_bad(pmd);
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 133f750..7669f4b 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -795,8 +795,8 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx,
 		 * (This includes the case where the PMD used to be THP and
 		 * changed back to none after __pte_alloc().)
 		 */
-		if (unlikely(!pmd_present(dst_pmdval) || pmd_trans_huge(dst_pmdval) ||
-			     pmd_devmap(dst_pmdval))) {
+		if (unlikely(!pmd_present(dst_pmdval) ||
+				pmd_trans_huge(dst_pmdval))) {
 			err = -EEXIST;
 			break;
 		}
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 61e6c44..8bf62b1 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3426,9 +3426,6 @@ static unsigned long get_pmd_pfn(pmd_t pmd, struct vm_area_struct *vma, unsigned
 	if (!pmd_present(pmd) || is_huge_zero_pmd(pmd))
 		return -1;
 
-	if (WARN_ON_ONCE(pmd_devmap(pmd)))
-		return -1;
-
 	if (!pmd_young(pmd) && !mm_has_notifiers(vma->vm_mm))
 		return -1;
 
-- 
git-series 0.9.1

[PATCH 08/12] mm/khugepaged: Remove redundant pmd_devmap() check

[Alistair Popple]

The only users of pmd_devmap were device dax and fs dax. The check for
pmd_devmap() in check_pmd_state() is therefore redundant as callers
explicitly check for is_zone_device_page(), so this check can be dropped.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 mm/khugepaged.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index cc945c6..7c2b9bc 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -958,8 +958,6 @@ static inline int check_pmd_state(pmd_t *pmd)
 		return SCAN_PMD_NULL;
 	if (pmd_trans_huge(pmde))
 		return SCAN_PMD_MAPPED;
-	if (pmd_devmap(pmde))
-		return SCAN_PMD_NULL;
 	if (pmd_bad(pmde))
 		return SCAN_PMD_NULL;
 	return SCAN_SUCCEED;
-- 
git-series 0.9.1

[PATCH 09/12] powerpc: Remove checks for devmap pages and PMDs/PUDs

[Alistair Popple]

PFN_DEV no longer exists. This means no devmap PMDs or PUDs will be
created, so checking for them is redundant. Instead mappings of pages that
would have previously returned true for pXd_devmap() will return true for
pXd_trans_huge()

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 arch/powerpc/mm/book3s64/hash_hugepage.c |  2 +-
 arch/powerpc/mm/book3s64/hash_pgtable.c  |  3 +--
 arch/powerpc/mm/book3s64/hugetlbpage.c   |  2 +-
 arch/powerpc/mm/book3s64/pgtable.c       | 10 ++++------
 arch/powerpc/mm/book3s64/radix_pgtable.c |  5 ++---
 arch/powerpc/mm/pgtable.c                |  2 +-
 6 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/mm/book3s64/hash_hugepage.c b/arch/powerpc/mm/book3s64/hash_hugepage.c
index 15d6f3e..cdfd4fe 100644
--- a/arch/powerpc/mm/book3s64/hash_hugepage.c
+++ b/arch/powerpc/mm/book3s64/hash_hugepage.c
@@ -54,7 +54,7 @@ int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
 	/*
 	 * Make sure this is thp or devmap entry
 	 */
-	if (!(old_pmd & (H_PAGE_THP_HUGE | _PAGE_DEVMAP)))
+	if (!(old_pmd & H_PAGE_THP_HUGE))
 		return 0;
 
 	rflags = htab_convert_pte_flags(new_pmd, flags);
diff --git a/arch/powerpc/mm/book3s64/hash_pgtable.c b/arch/powerpc/mm/book3s64/hash_pgtable.c
index 988948d..82d3117 100644
--- a/arch/powerpc/mm/book3s64/hash_pgtable.c
+++ b/arch/powerpc/mm/book3s64/hash_pgtable.c
@@ -195,7 +195,7 @@ unsigned long hash__pmd_hugepage_update(struct mm_struct *mm, unsigned long addr
 	unsigned long old;
 
 #ifdef CONFIG_DEBUG_VM
-	WARN_ON(!hash__pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp));
+	WARN_ON(!hash__pmd_trans_huge(*pmdp));
 	assert_spin_locked(pmd_lockptr(mm, pmdp));
 #endif
 
@@ -227,7 +227,6 @@ pmd_t hash__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long addres
 
 	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 	VM_BUG_ON(pmd_trans_huge(*pmdp));
-	VM_BUG_ON(pmd_devmap(*pmdp));
 
 	pmd = *pmdp;
 	pmd_clear(pmdp);
diff --git a/arch/powerpc/mm/book3s64/hugetlbpage.c b/arch/powerpc/mm/book3s64/hugetlbpage.c
index 83c3361..2bcbbf9 100644
--- a/arch/powerpc/mm/book3s64/hugetlbpage.c
+++ b/arch/powerpc/mm/book3s64/hugetlbpage.c
@@ -74,7 +74,7 @@ int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
 	} while(!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
 
 	/* Make sure this is a hugetlb entry */
-	if (old_pte & (H_PAGE_THP_HUGE | _PAGE_DEVMAP))
+	if (old_pte & H_PAGE_THP_HUGE)
 		return 0;
 
 	rflags = htab_convert_pte_flags(new_pte, flags);
diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 8f7d41c..4817db3 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -62,7 +62,7 @@ int pmdp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
 {
 	int changed;
 #ifdef CONFIG_DEBUG_VM
-	WARN_ON(!pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp));
+	WARN_ON(!pmd_trans_huge(*pmdp));
 	assert_spin_locked(pmd_lockptr(vma->vm_mm, pmdp));
 #endif
 	changed = !pmd_same(*(pmdp), entry);
@@ -82,7 +82,6 @@ int pudp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
 {
 	int changed;
 #ifdef CONFIG_DEBUG_VM
-	WARN_ON(!pud_devmap(*pudp));
 	assert_spin_locked(pud_lockptr(vma->vm_mm, pudp));
 #endif
 	changed = !pud_same(*(pudp), entry);
@@ -204,8 +203,8 @@ pmd_t pmdp_huge_get_and_clear_full(struct vm_area_struct *vma,
 {
 	pmd_t pmd;
 	VM_BUG_ON(addr & ~HPAGE_PMD_MASK);
-	VM_BUG_ON((pmd_present(*pmdp) && !pmd_trans_huge(*pmdp) &&
-		   !pmd_devmap(*pmdp)) || !pmd_present(*pmdp));
+	VM_BUG_ON((pmd_present(*pmdp) && !pmd_trans_huge(*pmdp)) ||
+		   !pmd_present(*pmdp));
 	pmd = pmdp_huge_get_and_clear(vma->vm_mm, addr, pmdp);
 	/*
 	 * if it not a fullmm flush, then we can possibly end up converting
@@ -223,8 +222,7 @@ pud_t pudp_huge_get_and_clear_full(struct vm_area_struct *vma,
 	pud_t pud;
 
 	VM_BUG_ON(addr & ~HPAGE_PMD_MASK);
-	VM_BUG_ON((pud_present(*pudp) && !pud_devmap(*pudp)) ||
-		  !pud_present(*pudp));
+	VM_BUG_ON(!pud_present(*pudp));
 	pud = pudp_huge_get_and_clear(vma->vm_mm, addr, pudp);
 	/*
 	 * if it not a fullmm flush, then we can possibly end up converting
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index 9f764bc..877870d 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -1426,7 +1426,7 @@ unsigned long radix__pmd_hugepage_update(struct mm_struct *mm, unsigned long add
 	unsigned long old;
 
 #ifdef CONFIG_DEBUG_VM
-	WARN_ON(!radix__pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp));
+	WARN_ON(!radix__pmd_trans_huge(*pmdp));
 	assert_spin_locked(pmd_lockptr(mm, pmdp));
 #endif
 
@@ -1443,7 +1443,7 @@ unsigned long radix__pud_hugepage_update(struct mm_struct *mm, unsigned long add
 	unsigned long old;
 
 #ifdef CONFIG_DEBUG_VM
-	WARN_ON(!pud_devmap(*pudp));
+	WARN_ON(!pud_trans_huge(*pudp));
 	assert_spin_locked(pud_lockptr(mm, pudp));
 #endif
 
@@ -1461,7 +1461,6 @@ pmd_t radix__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long addre
 
 	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 	VM_BUG_ON(radix__pmd_trans_huge(*pmdp));
-	VM_BUG_ON(pmd_devmap(*pmdp));
 	/*
 	 * khugepaged calls this for normal pmd
 	 */
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 61df5ae..dfaa9fd 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -509,7 +509,7 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
 		return NULL;
 #endif
 
-	if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) {
+	if (pmd_trans_huge(pmd)) {
 		if (is_thp)
 			*is_thp = true;
 		ret_pte = (pte_t *)pmdp;
-- 
git-series 0.9.1

[PATCH 10/12] mm: Remove devmap related functions and page table bits

[Alistair Popple]

Now that DAX and all other reference counts to ZONE_DEVICE pages are
managed normally there is no need for the special devmap PTE/PMD/PUD
page table bits. So drop all references to these, freeing up a
software defined page table bit on architectures supporting it.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: Will Deacon <will@kernel.org> # arm64
Suggested-by: Chunyan Zhang <zhang.lyra@gmail.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
---
 Documentation/mm/arch_pgtable_helpers.rst     |  6 +--
 arch/arm64/Kconfig                            |  1 +-
 arch/arm64/include/asm/pgtable-prot.h         |  1 +-
 arch/arm64/include/asm/pgtable.h              | 24 +--------
 arch/loongarch/Kconfig                        |  1 +-
 arch/loongarch/include/asm/pgtable-bits.h     |  6 +--
 arch/loongarch/include/asm/pgtable.h          | 19 +------
 arch/powerpc/Kconfig                          |  1 +-
 arch/powerpc/include/asm/book3s/64/hash-4k.h  |  6 +--
 arch/powerpc/include/asm/book3s/64/hash-64k.h |  7 +--
 arch/powerpc/include/asm/book3s/64/pgtable.h  | 53 +------------------
 arch/powerpc/include/asm/book3s/64/radix.h    | 14 +-----
 arch/riscv/Kconfig                            |  1 +-
 arch/riscv/include/asm/pgtable-64.h           | 20 +-------
 arch/riscv/include/asm/pgtable-bits.h         |  1 +-
 arch/riscv/include/asm/pgtable.h              | 17 +------
 arch/x86/Kconfig                              |  1 +-
 arch/x86/include/asm/pgtable.h                | 51 +-----------------
 arch/x86/include/asm/pgtable_types.h          |  5 +--
 include/linux/mm.h                            |  7 +--
 include/linux/pgtable.h                       | 19 +------
 mm/Kconfig                                    |  4 +-
 mm/debug_vm_pgtable.c                         | 59 +--------------------
 mm/hmm.c                                      |  3 +-
 mm/madvise.c                                  |  8 +--
 25 files changed, 17 insertions(+), 318 deletions(-)

diff --git a/Documentation/mm/arch_pgtable_helpers.rst b/Documentation/mm/arch_pgtable_helpers.rst
index af24516..c88c7fa 100644
--- a/Documentation/mm/arch_pgtable_helpers.rst
+++ b/Documentation/mm/arch_pgtable_helpers.rst
@@ -30,8 +30,6 @@ PTE Page Table Helpers
 +---------------------------+--------------------------------------------------+
 | pte_protnone              | Tests a PROT_NONE PTE                            |
 +---------------------------+--------------------------------------------------+
-| pte_devmap                | Tests a ZONE_DEVICE mapped PTE                   |
-+---------------------------+--------------------------------------------------+
 | pte_soft_dirty            | Tests a soft dirty PTE                           |
 +---------------------------+--------------------------------------------------+
 | pte_swp_soft_dirty        | Tests a soft dirty swapped PTE                   |
@@ -104,8 +102,6 @@ PMD Page Table Helpers
 +---------------------------+--------------------------------------------------+
 | pmd_protnone              | Tests a PROT_NONE PMD                            |
 +---------------------------+--------------------------------------------------+
-| pmd_devmap                | Tests a ZONE_DEVICE mapped PMD                   |
-+---------------------------+--------------------------------------------------+
 | pmd_soft_dirty            | Tests a soft dirty PMD                           |
 +---------------------------+--------------------------------------------------+
 | pmd_swp_soft_dirty        | Tests a soft dirty swapped PMD                   |
@@ -177,8 +173,6 @@ PUD Page Table Helpers
 +---------------------------+--------------------------------------------------+
 | pud_write                 | Tests a writable PUD                             |
 +---------------------------+--------------------------------------------------+
-| pud_devmap                | Tests a ZONE_DEVICE mapped PUD                   |
-+---------------------------+--------------------------------------------------+
 | pud_mkyoung               | Creates a young PUD                              |
 +---------------------------+--------------------------------------------------+
 | pud_mkold                 | Creates an old PUD                               |
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a182295..ee9031c 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -43,7 +43,6 @@ config ARM64
 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 	select ARCH_HAS_NONLEAF_PMD_YOUNG if ARM64_HAFT
 	select ARCH_HAS_PTDUMP
-	select ARCH_HAS_PTE_DEVMAP
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_HW_PTE_YOUNG
 	select ARCH_HAS_SETUP_DMA_OPS
diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
index 7830d03..85dceb1 100644
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -17,7 +17,6 @@
 #define PTE_SWP_EXCLUSIVE	(_AT(pteval_t, 1) << 2)	 /* only for swp ptes */
 #define PTE_DIRTY		(_AT(pteval_t, 1) << 55)
 #define PTE_SPECIAL		(_AT(pteval_t, 1) << 56)
-#define PTE_DEVMAP		(_AT(pteval_t, 1) << 57)
 
 /*
  * PTE_PRESENT_INVALID=1 & PTE_VALID=0 indicates that the pte's fields should be
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index d3b538b..991c9fa 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -111,7 +111,6 @@ static inline pteval_t __phys_to_pte_val(phys_addr_t phys)
 #define pte_user(pte)		(!!(pte_val(pte) & PTE_USER))
 #define pte_user_exec(pte)	(!(pte_val(pte) & PTE_UXN))
 #define pte_cont(pte)		(!!(pte_val(pte) & PTE_CONT))
-#define pte_devmap(pte)		(!!(pte_val(pte) & PTE_DEVMAP))
 #define pte_tagged(pte)		((pte_val(pte) & PTE_ATTRINDX_MASK) == \
 				 PTE_ATTRINDX(MT_NORMAL_TAGGED))
 
@@ -293,11 +292,6 @@ static inline pmd_t pmd_mkcont(pmd_t pmd)
 	return __pmd(pmd_val(pmd) | PMD_SECT_CONT);
 }
 
-static inline pte_t pte_mkdevmap(pte_t pte)
-{
-	return set_pte_bit(pte, __pgprot(PTE_DEVMAP | PTE_SPECIAL));
-}
-
 #ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP
 static inline int pte_uffd_wp(pte_t pte)
 {
@@ -589,14 +583,6 @@ static inline pmd_t pmd_mkhuge(pmd_t pmd)
 	return __pmd((pmd_val(pmd) & ~mask) | val);
 }
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-#define pmd_devmap(pmd)		pte_devmap(pmd_pte(pmd))
-#endif
-static inline pmd_t pmd_mkdevmap(pmd_t pmd)
-{
-	return pte_pmd(set_pte_bit(pmd_pte(pmd), __pgprot(PTE_DEVMAP)));
-}
-
 #ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
 #define pmd_special(pte)	(!!((pmd_val(pte) & PTE_SPECIAL)))
 static inline pmd_t pmd_mkspecial(pmd_t pmd)
@@ -1220,16 +1206,6 @@ static inline int pmdp_set_access_flags(struct vm_area_struct *vma,
 	return __ptep_set_access_flags(vma, address, (pte_t *)pmdp,
 							pmd_pte(entry), dirty);
 }
-
-static inline int pud_devmap(pud_t pud)
-{
-	return 0;
-}
-
-static inline int pgd_devmap(pgd_t pgd)
-{
-	return 0;
-}
 #endif
 
 #ifdef CONFIG_PAGE_TABLE_CHECK
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 1a2cf01..7b4b871 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -25,7 +25,6 @@ config LOONGARCH
 	select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 	select ARCH_HAS_PREEMPT_LAZY
-	select ARCH_HAS_PTE_DEVMAP
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_SET_MEMORY
 	select ARCH_HAS_SET_DIRECT_MAP
diff --git a/arch/loongarch/include/asm/pgtable-bits.h b/arch/loongarch/include/asm/pgtable-bits.h
index 45bfc65..c8777a9 100644
--- a/arch/loongarch/include/asm/pgtable-bits.h
+++ b/arch/loongarch/include/asm/pgtable-bits.h
@@ -22,7 +22,6 @@
 #define	_PAGE_PFN_SHIFT		12
 #define	_PAGE_SWP_EXCLUSIVE_SHIFT 23
 #define	_PAGE_PFN_END_SHIFT	48
-#define	_PAGE_DEVMAP_SHIFT	59
 #define	_PAGE_PRESENT_INVALID_SHIFT 60
 #define	_PAGE_NO_READ_SHIFT	61
 #define	_PAGE_NO_EXEC_SHIFT	62
@@ -36,7 +35,6 @@
 #define _PAGE_MODIFIED		(_ULCAST_(1) << _PAGE_MODIFIED_SHIFT)
 #define _PAGE_PROTNONE		(_ULCAST_(1) << _PAGE_PROTNONE_SHIFT)
 #define _PAGE_SPECIAL		(_ULCAST_(1) << _PAGE_SPECIAL_SHIFT)
-#define _PAGE_DEVMAP		(_ULCAST_(1) << _PAGE_DEVMAP_SHIFT)
 
 /* We borrow bit 23 to store the exclusive marker in swap PTEs. */
 #define _PAGE_SWP_EXCLUSIVE	(_ULCAST_(1) << _PAGE_SWP_EXCLUSIVE_SHIFT)
@@ -76,8 +74,8 @@
 #define __READABLE	(_PAGE_VALID)
 #define __WRITEABLE	(_PAGE_DIRTY | _PAGE_WRITE)
 
-#define _PAGE_CHG_MASK	(_PAGE_MODIFIED | _PAGE_SPECIAL | _PAGE_DEVMAP | _PFN_MASK | _CACHE_MASK | _PAGE_PLV)
-#define _HPAGE_CHG_MASK	(_PAGE_MODIFIED | _PAGE_SPECIAL | _PAGE_DEVMAP | _PFN_MASK | _CACHE_MASK | _PAGE_PLV | _PAGE_HUGE)
+#define _PAGE_CHG_MASK	(_PAGE_MODIFIED | _PAGE_SPECIAL | _PFN_MASK | _CACHE_MASK | _PAGE_PLV)
+#define _HPAGE_CHG_MASK	(_PAGE_MODIFIED | _PAGE_SPECIAL | _PFN_MASK | _CACHE_MASK | _PAGE_PLV | _PAGE_HUGE)
 
 #define PAGE_NONE	__pgprot(_PAGE_PROTNONE | _PAGE_NO_READ | \
 				 _PAGE_USER | _CACHE_CC)
diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
index da34673..d83b14b 100644
--- a/arch/loongarch/include/asm/pgtable.h
+++ b/arch/loongarch/include/asm/pgtable.h
@@ -410,9 +410,6 @@ static inline int pte_special(pte_t pte)	{ return pte_val(pte) & _PAGE_SPECIAL; 
 static inline pte_t pte_mkspecial(pte_t pte)	{ pte_val(pte) |= _PAGE_SPECIAL; return pte; }
 #endif /* CONFIG_ARCH_HAS_PTE_SPECIAL */
 
-static inline int pte_devmap(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_DEVMAP); }
-static inline pte_t pte_mkdevmap(pte_t pte)	{ pte_val(pte) |= _PAGE_DEVMAP; return pte; }
-
 #define pte_accessible pte_accessible
 static inline unsigned long pte_accessible(struct mm_struct *mm, pte_t a)
 {
@@ -547,17 +544,6 @@ static inline pmd_t pmd_mkyoung(pmd_t pmd)
 	return pmd;
 }
 
-static inline int pmd_devmap(pmd_t pmd)
-{
-	return !!(pmd_val(pmd) & _PAGE_DEVMAP);
-}
-
-static inline pmd_t pmd_mkdevmap(pmd_t pmd)
-{
-	pmd_val(pmd) |= _PAGE_DEVMAP;
-	return pmd;
-}
-
 static inline struct page *pmd_page(pmd_t pmd)
 {
 	if (pmd_trans_huge(pmd))
@@ -613,11 +599,6 @@ static inline long pmd_protnone(pmd_t pmd)
 #define pmd_leaf(pmd)		((pmd_val(pmd) & _PAGE_HUGE) != 0)
 #define pud_leaf(pud)		((pud_val(pud) & _PAGE_HUGE) != 0)
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-#define pud_devmap(pud)		(0)
-#define pgd_devmap(pgd)		(0)
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
-
 /*
  * We provide our own get_unmapped area to cope with the virtual aliasing
  * constraints placed on us by the cache architecture.
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 6722625..486b53b 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -149,7 +149,6 @@ config PPC
 	select ARCH_HAS_PMEM_API
 	select ARCH_HAS_PREEMPT_LAZY
 	select ARCH_HAS_PTDUMP
-	select ARCH_HAS_PTE_DEVMAP		if PPC_BOOK3S_64
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_SCALED_CPUTIME		if VIRT_CPU_ACCOUNTING_NATIVE && PPC_BOOK3S_64
 	select ARCH_HAS_SET_MEMORY
diff --git a/arch/powerpc/include/asm/book3s/64/hash-4k.h b/arch/powerpc/include/asm/book3s/64/hash-4k.h
index aa90a04..7132392 100644
--- a/arch/powerpc/include/asm/book3s/64/hash-4k.h
+++ b/arch/powerpc/include/asm/book3s/64/hash-4k.h
@@ -168,12 +168,6 @@ extern pmd_t hash__pmdp_huge_get_and_clear(struct mm_struct *mm,
 extern int hash__has_transparent_hugepage(void);
 #endif
 
-static inline pmd_t hash__pmd_mkdevmap(pmd_t pmd)
-{
-	BUG();
-	return pmd;
-}
-
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _ASM_POWERPC_BOOK3S_64_HASH_4K_H */
diff --git a/arch/powerpc/include/asm/book3s/64/hash-64k.h b/arch/powerpc/include/asm/book3s/64/hash-64k.h
index 0bf6fd0..0fb5b7d 100644
--- a/arch/powerpc/include/asm/book3s/64/hash-64k.h
+++ b/arch/powerpc/include/asm/book3s/64/hash-64k.h
@@ -259,7 +259,7 @@ static inline void mark_hpte_slot_valid(unsigned char *hpte_slot_array,
  */
 static inline int hash__pmd_trans_huge(pmd_t pmd)
 {
-	return !!((pmd_val(pmd) & (_PAGE_PTE | H_PAGE_THP_HUGE | _PAGE_DEVMAP)) ==
+	return !!((pmd_val(pmd) & (_PAGE_PTE | H_PAGE_THP_HUGE)) ==
 		  (_PAGE_PTE | H_PAGE_THP_HUGE));
 }
 
@@ -281,11 +281,6 @@ extern pmd_t hash__pmdp_huge_get_and_clear(struct mm_struct *mm,
 extern int hash__has_transparent_hugepage(void);
 #endif /*  CONFIG_TRANSPARENT_HUGEPAGE */
 
-static inline pmd_t hash__pmd_mkdevmap(pmd_t pmd)
-{
-	return __pmd(pmd_val(pmd) | (_PAGE_PTE | H_PAGE_THP_HUGE | _PAGE_DEVMAP));
-}
-
 #endif	/* __ASSEMBLY__ */
 
 #endif /* _ASM_POWERPC_BOOK3S_64_HASH_64K_H */
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 6d98e6f..1d98d0a 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -88,7 +88,6 @@
 
 #define _PAGE_SOFT_DIRTY	_RPAGE_SW3 /* software: software dirty tracking */
 #define _PAGE_SPECIAL		_RPAGE_SW2 /* software: special page */
-#define _PAGE_DEVMAP		_RPAGE_SW1 /* software: ZONE_DEVICE page */
 
 /*
  * Drivers request for cache inhibited pte mapping using _PAGE_NO_CACHE
@@ -109,7 +108,7 @@
  */
 #define _HPAGE_CHG_MASK (PTE_RPN_MASK | _PAGE_HPTEFLAGS | _PAGE_DIRTY | \
 			 _PAGE_ACCESSED | H_PAGE_THP_HUGE | _PAGE_PTE | \
-			 _PAGE_SOFT_DIRTY | _PAGE_DEVMAP)
+			 _PAGE_SOFT_DIRTY)
 /*
  * user access blocked by key
  */
@@ -123,7 +122,7 @@
  */
 #define _PAGE_CHG_MASK	(PTE_RPN_MASK | _PAGE_HPTEFLAGS | _PAGE_DIRTY | \
 			 _PAGE_ACCESSED | _PAGE_SPECIAL | _PAGE_PTE |	\
-			 _PAGE_SOFT_DIRTY | _PAGE_DEVMAP)
+			 _PAGE_SOFT_DIRTY)
 
 /*
  * We define 2 sets of base prot bits, one for basic pages (ie,
@@ -609,24 +608,6 @@ static inline pte_t pte_mkhuge(pte_t pte)
 	return pte;
 }
 
-static inline pte_t pte_mkdevmap(pte_t pte)
-{
-	return __pte_raw(pte_raw(pte) | cpu_to_be64(_PAGE_SPECIAL | _PAGE_DEVMAP));
-}
-
-/*
- * This is potentially called with a pmd as the argument, in which case it's not
- * safe to check _PAGE_DEVMAP unless we also confirm that _PAGE_PTE is set.
- * That's because the bit we use for _PAGE_DEVMAP is not reserved for software
- * use in page directory entries (ie. non-ptes).
- */
-static inline int pte_devmap(pte_t pte)
-{
-	__be64 mask = cpu_to_be64(_PAGE_DEVMAP | _PAGE_PTE);
-
-	return (pte_raw(pte) & mask) == mask;
-}
-
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
 	/* FIXME!! check whether this need to be a conditional */
@@ -1380,36 +1361,6 @@ static inline bool arch_needs_pgtable_deposit(void)
 }
 extern void serialize_against_pte_lookup(struct mm_struct *mm);
 
-
-static inline pmd_t pmd_mkdevmap(pmd_t pmd)
-{
-	if (radix_enabled())
-		return radix__pmd_mkdevmap(pmd);
-	return hash__pmd_mkdevmap(pmd);
-}
-
-static inline pud_t pud_mkdevmap(pud_t pud)
-{
-	if (radix_enabled())
-		return radix__pud_mkdevmap(pud);
-	BUG();
-	return pud;
-}
-
-static inline int pmd_devmap(pmd_t pmd)
-{
-	return pte_devmap(pmd_pte(pmd));
-}
-
-static inline int pud_devmap(pud_t pud)
-{
-	return pte_devmap(pud_pte(pud));
-}
-
-static inline int pgd_devmap(pgd_t pgd)
-{
-	return 0;
-}
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 #define __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
index 8f55ff7..df23a82 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -264,7 +264,7 @@ static inline int radix__p4d_bad(p4d_t p4d)
 
 static inline int radix__pmd_trans_huge(pmd_t pmd)
 {
-	return (pmd_val(pmd) & (_PAGE_PTE | _PAGE_DEVMAP)) == _PAGE_PTE;
+	return (pmd_val(pmd) & _PAGE_PTE) == _PAGE_PTE;
 }
 
 static inline pmd_t radix__pmd_mkhuge(pmd_t pmd)
@@ -274,7 +274,7 @@ static inline pmd_t radix__pmd_mkhuge(pmd_t pmd)
 
 static inline int radix__pud_trans_huge(pud_t pud)
 {
-	return (pud_val(pud) & (_PAGE_PTE | _PAGE_DEVMAP)) == _PAGE_PTE;
+	return (pud_val(pud) & _PAGE_PTE) == _PAGE_PTE;
 }
 
 static inline pud_t radix__pud_mkhuge(pud_t pud)
@@ -315,16 +315,6 @@ static inline int radix__has_transparent_pud_hugepage(void)
 }
 #endif
 
-static inline pmd_t radix__pmd_mkdevmap(pmd_t pmd)
-{
-	return __pmd(pmd_val(pmd) | (_PAGE_PTE | _PAGE_DEVMAP));
-}
-
-static inline pud_t radix__pud_mkdevmap(pud_t pud)
-{
-	return __pud(pud_val(pud) | (_PAGE_PTE | _PAGE_DEVMAP));
-}
-
 struct vmem_altmap;
 struct dev_pagemap;
 extern int __meminit radix__vmemmap_create_mapping(unsigned long start,
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index bbec87b..184acf0 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -46,7 +46,6 @@ config RISCV
 	select ARCH_HAS_PREEMPT_LAZY
 	select ARCH_HAS_PREPARE_SYNC_CORE_CMD
 	select ARCH_HAS_PTDUMP if MMU
-	select ARCH_HAS_PTE_DEVMAP if 64BIT && MMU
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_SET_DIRECT_MAP if MMU
 	select ARCH_HAS_SET_MEMORY if MMU
diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
index 0897dd9..8c36a88 100644
--- a/arch/riscv/include/asm/pgtable-64.h
+++ b/arch/riscv/include/asm/pgtable-64.h
@@ -398,24 +398,4 @@ static inline struct page *pgd_page(pgd_t pgd)
 #define p4d_offset p4d_offset
 p4d_t *p4d_offset(pgd_t *pgd, unsigned long address);
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-static inline int pte_devmap(pte_t pte);
-static inline pte_t pmd_pte(pmd_t pmd);
-
-static inline int pmd_devmap(pmd_t pmd)
-{
-	return pte_devmap(pmd_pte(pmd));
-}
-
-static inline int pud_devmap(pud_t pud)
-{
-	return 0;
-}
-
-static inline int pgd_devmap(pgd_t pgd)
-{
-	return 0;
-}
-#endif
-
 #endif /* _ASM_RISCV_PGTABLE_64_H */
diff --git a/arch/riscv/include/asm/pgtable-bits.h b/arch/riscv/include/asm/pgtable-bits.h
index a8f5205..179bd4a 100644
--- a/arch/riscv/include/asm/pgtable-bits.h
+++ b/arch/riscv/include/asm/pgtable-bits.h
@@ -19,7 +19,6 @@
 #define _PAGE_SOFT      (3 << 8)    /* Reserved for software */
 
 #define _PAGE_SPECIAL   (1 << 8)    /* RSW: 0x1 */
-#define _PAGE_DEVMAP    (1 << 9)    /* RSW, devmap */
 #define _PAGE_TABLE     _PAGE_PRESENT
 
 /*
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 428e48e..c602070 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -411,13 +411,6 @@ static inline int pte_special(pte_t pte)
 	return pte_val(pte) & _PAGE_SPECIAL;
 }
 
-#ifdef CONFIG_ARCH_HAS_PTE_DEVMAP
-static inline int pte_devmap(pte_t pte)
-{
-	return pte_val(pte) & _PAGE_DEVMAP;
-}
-#endif
-
 /* static inline pte_t pte_rdprotect(pte_t pte) */
 
 static inline pte_t pte_wrprotect(pte_t pte)
@@ -459,11 +452,6 @@ static inline pte_t pte_mkspecial(pte_t pte)
 	return __pte(pte_val(pte) | _PAGE_SPECIAL);
 }
 
-static inline pte_t pte_mkdevmap(pte_t pte)
-{
-	return __pte(pte_val(pte) | _PAGE_DEVMAP);
-}
-
 static inline pte_t pte_mkhuge(pte_t pte)
 {
 	return pte;
@@ -792,11 +780,6 @@ static inline pmd_t pmd_mkdirty(pmd_t pmd)
 	return pte_pmd(pte_mkdirty(pmd_pte(pmd)));
 }
 
-static inline pmd_t pmd_mkdevmap(pmd_t pmd)
-{
-	return pte_pmd(pte_mkdevmap(pmd_pte(pmd)));
-}
-
 #ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
 static inline bool pmd_special(pmd_t pmd)
 {
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e21cca4..00f2665 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -100,7 +100,6 @@ config X86
 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 	select ARCH_HAS_PMEM_API		if X86_64
 	select ARCH_HAS_PREEMPT_LAZY
-	select ARCH_HAS_PTE_DEVMAP		if X86_64
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_HW_PTE_YOUNG
 	select ARCH_HAS_NONLEAF_PMD_YOUNG	if PGTABLE_LEVELS > 2
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 7bd6bd6..141d13e 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -308,16 +308,15 @@ static inline bool pmd_leaf(pmd_t pte)
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-/* NOTE: when predicate huge page, consider also pmd_devmap, or use pmd_leaf */
 static inline int pmd_trans_huge(pmd_t pmd)
 {
-	return (pmd_val(pmd) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
+	return (pmd_val(pmd) & _PAGE_PSE) == _PAGE_PSE;
 }
 
 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 static inline int pud_trans_huge(pud_t pud)
 {
-	return (pud_val(pud) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
+	return (pud_val(pud) & _PAGE_PSE) == _PAGE_PSE;
 }
 #endif
 
@@ -327,24 +326,6 @@ static inline int has_transparent_hugepage(void)
 	return boot_cpu_has(X86_FEATURE_PSE);
 }
 
-#ifdef CONFIG_ARCH_HAS_PTE_DEVMAP
-static inline int pmd_devmap(pmd_t pmd)
-{
-	return !!(pmd_val(pmd) & _PAGE_DEVMAP);
-}
-
-#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
-static inline int pud_devmap(pud_t pud)
-{
-	return !!(pud_val(pud) & _PAGE_DEVMAP);
-}
-#else
-static inline int pud_devmap(pud_t pud)
-{
-	return 0;
-}
-#endif
-
 #ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
 static inline bool pmd_special(pmd_t pmd)
 {
@@ -368,12 +349,6 @@ static inline pud_t pud_mkspecial(pud_t pud)
 	return pud_set_flags(pud, _PAGE_SPECIAL);
 }
 #endif	/* CONFIG_ARCH_SUPPORTS_PUD_PFNMAP */
-
-static inline int pgd_devmap(pgd_t pgd)
-{
-	return 0;
-}
-#endif
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 static inline pte_t pte_set_flags(pte_t pte, pteval_t set)
@@ -534,11 +509,6 @@ static inline pte_t pte_mkspecial(pte_t pte)
 	return pte_set_flags(pte, _PAGE_SPECIAL);
 }
 
-static inline pte_t pte_mkdevmap(pte_t pte)
-{
-	return pte_set_flags(pte, _PAGE_SPECIAL|_PAGE_DEVMAP);
-}
-
 /* See comments above mksaveddirty_shift() */
 static inline pmd_t pmd_mksaveddirty(pmd_t pmd)
 {
@@ -610,11 +580,6 @@ static inline pmd_t pmd_mkwrite_shstk(pmd_t pmd)
 	return pmd_set_flags(pmd, _PAGE_DIRTY);
 }
 
-static inline pmd_t pmd_mkdevmap(pmd_t pmd)
-{
-	return pmd_set_flags(pmd, _PAGE_DEVMAP);
-}
-
 static inline pmd_t pmd_mkhuge(pmd_t pmd)
 {
 	return pmd_set_flags(pmd, _PAGE_PSE);
@@ -680,11 +645,6 @@ static inline pud_t pud_mkdirty(pud_t pud)
 	return pud_mksaveddirty(pud);
 }
 
-static inline pud_t pud_mkdevmap(pud_t pud)
-{
-	return pud_set_flags(pud, _PAGE_DEVMAP);
-}
-
 static inline pud_t pud_mkhuge(pud_t pud)
 {
 	return pud_set_flags(pud, _PAGE_PSE);
@@ -1012,13 +972,6 @@ static inline int pte_present(pte_t a)
 	return pte_flags(a) & (_PAGE_PRESENT | _PAGE_PROTNONE);
 }
 
-#ifdef CONFIG_ARCH_HAS_PTE_DEVMAP
-static inline int pte_devmap(pte_t a)
-{
-	return (pte_flags(a) & _PAGE_DEVMAP) == _PAGE_DEVMAP;
-}
-#endif
-
 #define pte_accessible pte_accessible
 static inline bool pte_accessible(struct mm_struct *mm, pte_t a)
 {
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index b74ec5c..f63ae8d 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -34,7 +34,6 @@
 #define _PAGE_BIT_UFFD_WP	_PAGE_BIT_SOFTW2 /* userfaultfd wrprotected */
 #define _PAGE_BIT_SOFT_DIRTY	_PAGE_BIT_SOFTW3 /* software dirty tracking */
 #define _PAGE_BIT_KERNEL_4K	_PAGE_BIT_SOFTW3 /* page must not be converted to large */
-#define _PAGE_BIT_DEVMAP	_PAGE_BIT_SOFTW4
 
 #ifdef CONFIG_X86_64
 #define _PAGE_BIT_SAVED_DIRTY	_PAGE_BIT_SOFTW5 /* Saved Dirty bit (leaf) */
@@ -121,11 +120,9 @@
 
 #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
 #define _PAGE_NX	(_AT(pteval_t, 1) << _PAGE_BIT_NX)
-#define _PAGE_DEVMAP	(_AT(u64, 1) << _PAGE_BIT_DEVMAP)
 #define _PAGE_SOFTW4	(_AT(pteval_t, 1) << _PAGE_BIT_SOFTW4)
 #else
 #define _PAGE_NX	(_AT(pteval_t, 0))
-#define _PAGE_DEVMAP	(_AT(pteval_t, 0))
 #define _PAGE_SOFTW4	(_AT(pteval_t, 0))
 #endif
 
@@ -154,7 +151,7 @@
 #define _COMMON_PAGE_CHG_MASK	(PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT |	\
 				 _PAGE_SPECIAL | _PAGE_ACCESSED |	\
 				 _PAGE_DIRTY_BITS | _PAGE_SOFT_DIRTY |	\
-				 _PAGE_DEVMAP | _PAGE_CC | _PAGE_UFFD_WP)
+				 _PAGE_CC | _PAGE_UFFD_WP)
 #define _PAGE_CHG_MASK	(_COMMON_PAGE_CHG_MASK | _PAGE_PAT)
 #define _HPAGE_CHG_MASK (_COMMON_PAGE_CHG_MASK | _PAGE_PSE | _PAGE_PAT_LARGE)
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bf55206..c5345ee 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2827,13 +2827,6 @@ static inline pud_t pud_mkspecial(pud_t pud)
 }
 #endif	/* CONFIG_ARCH_SUPPORTS_PUD_PFNMAP */
 
-#ifndef CONFIG_ARCH_HAS_PTE_DEVMAP
-static inline int pte_devmap(pte_t pte)
-{
-	return 0;
-}
-#endif
-
 extern pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
 			       spinlock_t **ptl);
 static inline pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index a6f9573..ed3317e 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1627,21 +1627,6 @@ static inline int pud_write(pud_t pud)
 }
 #endif /* pud_write */
 
-#if !defined(CONFIG_ARCH_HAS_PTE_DEVMAP) || !defined(CONFIG_TRANSPARENT_HUGEPAGE)
-static inline int pmd_devmap(pmd_t pmd)
-{
-	return 0;
-}
-static inline int pud_devmap(pud_t pud)
-{
-	return 0;
-}
-static inline int pgd_devmap(pgd_t pgd)
-{
-	return 0;
-}
-#endif
-
 #if !defined(CONFIG_TRANSPARENT_HUGEPAGE) || \
 	!defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
 static inline int pud_trans_huge(pud_t pud)
@@ -1896,8 +1881,8 @@ typedef unsigned int pgtbl_mod_mask;
  * - It should contain a huge PFN, which points to a huge page larger than
  *   PAGE_SIZE of the platform.  The PFN format isn't important here.
  *
- * - It should cover all kinds of huge mappings (e.g., pXd_trans_huge(),
- *   pXd_devmap(), or hugetlb mappings).
+ * - It should cover all kinds of huge mappings (i.e. pXd_trans_huge()
+ *   or hugetlb mappings).
  */
 #ifndef pgd_leaf
 #define pgd_leaf(x)	false
diff --git a/mm/Kconfig b/mm/Kconfig
index e113f71..626b5f5 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1071,9 +1071,6 @@ config ARCH_HAS_CURRENT_STACK_POINTER
 	  register alias named "current_stack_pointer", this config can be
 	  selected.
 
-config ARCH_HAS_PTE_DEVMAP
-	bool
-
 config ARCH_HAS_ZONE_DMA_SET
 	bool
 
@@ -1091,7 +1088,6 @@ config ZONE_DEVICE
 	depends on MEMORY_HOTPLUG
 	depends on MEMORY_HOTREMOVE
 	depends on SPARSEMEM_VMEMMAP
-	depends on ARCH_HAS_PTE_DEVMAP
 	select XARRAY_MULTI
 
 	help
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index bc748f7..cf5ff92 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -348,12 +348,6 @@ static void __init pud_advanced_tests(struct pgtable_debug_args *args)
 	vaddr &= HPAGE_PUD_MASK;
 
 	pud = pfn_pud(args->pud_pfn, args->page_prot);
-	/*
-	 * Some architectures have debug checks to make sure
-	 * huge pud mapping are only found with devmap entries
-	 * For now test with only devmap entries.
-	 */
-	pud = pud_mkdevmap(pud);
 	set_pud_at(args->mm, vaddr, args->pudp, pud);
 	flush_dcache_page(page);
 	pudp_set_wrprotect(args->mm, vaddr, args->pudp);
@@ -366,7 +360,6 @@ static void __init pud_advanced_tests(struct pgtable_debug_args *args)
 	WARN_ON(!pud_none(pud));
 #endif /* __PAGETABLE_PMD_FOLDED */
 	pud = pfn_pud(args->pud_pfn, args->page_prot);
-	pud = pud_mkdevmap(pud);
 	pud = pud_wrprotect(pud);
 	pud = pud_mkclean(pud);
 	set_pud_at(args->mm, vaddr, args->pudp, pud);
@@ -384,7 +377,6 @@ static void __init pud_advanced_tests(struct pgtable_debug_args *args)
 #endif /* __PAGETABLE_PMD_FOLDED */
 
 	pud = pfn_pud(args->pud_pfn, args->page_prot);
-	pud = pud_mkdevmap(pud);
 	pud = pud_mkyoung(pud);
 	set_pud_at(args->mm, vaddr, args->pudp, pud);
 	flush_dcache_page(page);
@@ -693,53 +685,6 @@ static void __init pmd_protnone_tests(struct pgtable_debug_args *args)
 static void __init pmd_protnone_tests(struct pgtable_debug_args *args) { }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
-#ifdef CONFIG_ARCH_HAS_PTE_DEVMAP
-static void __init pte_devmap_tests(struct pgtable_debug_args *args)
-{
-	pte_t pte = pfn_pte(args->fixed_pte_pfn, args->page_prot);
-
-	pr_debug("Validating PTE devmap\n");
-	WARN_ON(!pte_devmap(pte_mkdevmap(pte)));
-}
-
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-static void __init pmd_devmap_tests(struct pgtable_debug_args *args)
-{
-	pmd_t pmd;
-
-	if (!has_transparent_hugepage())
-		return;
-
-	pr_debug("Validating PMD devmap\n");
-	pmd = pfn_pmd(args->fixed_pmd_pfn, args->page_prot);
-	WARN_ON(!pmd_devmap(pmd_mkdevmap(pmd)));
-}
-
-#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
-static void __init pud_devmap_tests(struct pgtable_debug_args *args)
-{
-	pud_t pud;
-
-	if (!has_transparent_pud_hugepage())
-		return;
-
-	pr_debug("Validating PUD devmap\n");
-	pud = pfn_pud(args->fixed_pud_pfn, args->page_prot);
-	WARN_ON(!pud_devmap(pud_mkdevmap(pud)));
-}
-#else  /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
-static void __init pud_devmap_tests(struct pgtable_debug_args *args) { }
-#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
-#else  /* CONFIG_TRANSPARENT_HUGEPAGE */
-static void __init pmd_devmap_tests(struct pgtable_debug_args *args) { }
-static void __init pud_devmap_tests(struct pgtable_debug_args *args) { }
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
-#else
-static void __init pte_devmap_tests(struct pgtable_debug_args *args) { }
-static void __init pmd_devmap_tests(struct pgtable_debug_args *args) { }
-static void __init pud_devmap_tests(struct pgtable_debug_args *args) { }
-#endif /* CONFIG_ARCH_HAS_PTE_DEVMAP */
-
 static void __init pte_soft_dirty_tests(struct pgtable_debug_args *args)
 {
 	pte_t pte = pfn_pte(args->fixed_pte_pfn, args->page_prot);
@@ -1341,10 +1286,6 @@ static int __init debug_vm_pgtable(void)
 	pte_protnone_tests(&args);
 	pmd_protnone_tests(&args);
 
-	pte_devmap_tests(&args);
-	pmd_devmap_tests(&args);
-	pud_devmap_tests(&args);
-
 	pte_soft_dirty_tests(&args);
 	pmd_soft_dirty_tests(&args);
 	pte_swap_soft_dirty_tests(&args);
diff --git a/mm/hmm.c b/mm/hmm.c
index 5037f98..1fbbeea 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -393,8 +393,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
 	return 0;
 }
 
-#if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && \
-    defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
+#if defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
 static inline unsigned long pud_to_hmm_pfn_flags(struct hmm_range *range,
 						 pud_t pud)
 {
diff --git a/mm/madvise.c b/mm/madvise.c
index b17f684..6800f7e 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1066,7 +1066,7 @@ static int guard_install_pud_entry(pud_t *pud, unsigned long addr,
 	pud_t pudval = pudp_get(pud);
 
 	/* If huge return >0 so we abort the operation + zap. */
-	return pud_trans_huge(pudval) || pud_devmap(pudval);
+	return pud_trans_huge(pudval);
 }
 
 static int guard_install_pmd_entry(pmd_t *pmd, unsigned long addr,
@@ -1075,7 +1075,7 @@ static int guard_install_pmd_entry(pmd_t *pmd, unsigned long addr,
 	pmd_t pmdval = pmdp_get(pmd);
 
 	/* If huge return >0 so we abort the operation + zap. */
-	return pmd_trans_huge(pmdval) || pmd_devmap(pmdval);
+	return pmd_trans_huge(pmdval);
 }
 
 static int guard_install_pte_entry(pte_t *pte, unsigned long addr,
@@ -1186,7 +1186,7 @@ static int guard_remove_pud_entry(pud_t *pud, unsigned long addr,
 	pud_t pudval = pudp_get(pud);
 
 	/* If huge, cannot have guard pages present, so no-op - skip. */
-	if (pud_trans_huge(pudval) || pud_devmap(pudval))
+	if (pud_trans_huge(pudval))
 		walk->action = ACTION_CONTINUE;
 
 	return 0;
@@ -1198,7 +1198,7 @@ static int guard_remove_pmd_entry(pmd_t *pmd, unsigned long addr,
 	pmd_t pmdval = pmdp_get(pmd);
 
 	/* If huge, cannot have guard pages present, so no-op - skip. */
-	if (pmd_trans_huge(pmdval) || pmd_devmap(pmdval))
+	if (pmd_trans_huge(pmdval))
 		walk->action = ACTION_CONTINUE;
 
 	return 0;
-- 
git-series 0.9.1

[PATCH 11/12] mm: Remove callers of pfn_t functionality

[Alistair Popple]

All PFN_* pfn_t flags have been removed. Therefore there is no longer
a need for the pfn_t type and all uses can be replaced with normal
pfns.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/mm/pat/memtype.c                |  6 +-
 drivers/dax/device.c                     | 23 +++----
 drivers/dax/hmem/hmem.c                  |  1 +-
 drivers/dax/kmem.c                       |  1 +-
 drivers/dax/pmem.c                       |  1 +-
 drivers/dax/super.c                      |  3 +-
 drivers/gpu/drm/exynos/exynos_drm_gem.c  |  1 +-
 drivers/gpu/drm/gma500/fbdev.c           |  3 +-
 drivers/gpu/drm/i915/gem/i915_gem_mman.c |  1 +-
 drivers/gpu/drm/msm/msm_gem.c            |  1 +-
 drivers/gpu/drm/omapdrm/omap_gem.c       |  6 +--
 drivers/gpu/drm/v3d/v3d_bo.c             |  1 +-
 drivers/hwtracing/intel_th/msu.c         |  3 +-
 drivers/md/dm-linear.c                   |  2 +-
 drivers/md/dm-log-writes.c               |  2 +-
 drivers/md/dm-stripe.c                   |  2 +-
 drivers/md/dm-target.c                   |  2 +-
 drivers/md/dm-writecache.c               | 11 +--
 drivers/md/dm.c                          |  2 +-
 drivers/nvdimm/pmem.c                    |  8 +--
 drivers/nvdimm/pmem.h                    |  4 +-
 drivers/s390/block/dcssblk.c             |  9 +--
 drivers/vfio/pci/vfio_pci_core.c         |  5 +-
 fs/cramfs/inode.c                        |  5 +-
 fs/dax.c                                 | 50 +++++++--------
 fs/ext4/file.c                           |  2 +-
 fs/fuse/dax.c                            |  3 +-
 fs/fuse/virtio_fs.c                      |  5 +-
 fs/xfs/xfs_file.c                        |  2 +-
 include/linux/dax.h                      |  9 +--
 include/linux/device-mapper.h            |  2 +-
 include/linux/huge_mm.h                  |  6 +-
 include/linux/mm.h                       |  4 +-
 include/linux/pfn.h                      |  9 +---
 include/linux/pfn_t.h                    | 85 +-------------------------
 include/linux/pgtable.h                  |  4 +-
 include/trace/events/fs_dax.h            | 12 +---
 mm/debug_vm_pgtable.c                    |  1 +-
 mm/huge_memory.c                         | 27 +++-----
 mm/memory.c                              | 31 ++++-----
 mm/memremap.c                            |  1 +-
 mm/migrate.c                             |  1 +-
 tools/testing/nvdimm/pmem-dax.c          |  6 +-
 tools/testing/nvdimm/test/iomap.c        |  7 +--
 tools/testing/nvdimm/test/nfit_test.h    |  1 +-
 45 files changed, 121 insertions(+), 250 deletions(-)
 delete mode 100644 include/linux/pfn_t.h

diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c
index 72d8cbc..1fb57c2 100644
--- a/arch/x86/mm/pat/memtype.c
+++ b/arch/x86/mm/pat/memtype.c
@@ -36,7 +36,6 @@
 #include <linux/debugfs.h>
 #include <linux/ioport.h>
 #include <linux/kernel.h>
-#include <linux/pfn_t.h>
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/highmem.h>
@@ -1066,7 +1065,8 @@ int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
 	return 0;
 }
 
-void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, pfn_t pfn)
+void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
+		      unsigned long pfn)
 {
 	enum page_cache_mode pcm;
 
@@ -1074,7 +1074,7 @@ void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, pfn_t pfn)
 		return;
 
 	/* Set prot based on lookup */
-	pcm = lookup_memtype(pfn_t_to_phys(pfn));
+	pcm = lookup_memtype(PFN_PHYS(pfn));
 	*prot = __pgprot((pgprot_val(*prot) & (~_PAGE_CACHE_MASK)) |
 			 cachemode2protval(pcm));
 }
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 328231c..2bb40a6 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -4,7 +4,6 @@
 #include <linux/pagemap.h>
 #include <linux/module.h>
 #include <linux/device.h>
-#include <linux/pfn_t.h>
 #include <linux/cdev.h>
 #include <linux/slab.h>
 #include <linux/dax.h>
@@ -73,7 +72,7 @@ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
 	return -1;
 }
 
-static void dax_set_mapping(struct vm_fault *vmf, pfn_t pfn,
+static void dax_set_mapping(struct vm_fault *vmf, unsigned long pfn,
 			      unsigned long fault_size)
 {
 	unsigned long i, nr_pages = fault_size / PAGE_SIZE;
@@ -89,7 +88,7 @@ static void dax_set_mapping(struct vm_fault *vmf, pfn_t pfn,
 			ALIGN_DOWN(vmf->address, fault_size));
 
 	for (i = 0; i < nr_pages; i++) {
-		struct folio *folio = pfn_folio(pfn_t_to_pfn(pfn) + i);
+		struct folio *folio = pfn_folio(pfn + i);
 
 		if (folio->mapping)
 			continue;
@@ -104,7 +103,7 @@ static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
 {
 	struct device *dev = &dev_dax->dev;
 	phys_addr_t phys;
-	pfn_t pfn;
+	unsigned long pfn;
 	unsigned int fault_size = PAGE_SIZE;
 
 	if (check_vma(dev_dax, vmf->vma, __func__))
@@ -125,11 +124,11 @@ static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
 		return VM_FAULT_SIGBUS;
 	}
 
-	pfn = phys_to_pfn_t(phys, 0);
+	pfn = PHYS_PFN(phys);
 
 	dax_set_mapping(vmf, pfn, fault_size);
 
-	return vmf_insert_page_mkwrite(vmf, pfn_t_to_page(pfn),
+	return vmf_insert_page_mkwrite(vmf, pfn_to_page(pfn),
 					vmf->flags & FAULT_FLAG_WRITE);
 }
 
@@ -140,7 +139,7 @@ static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
 	struct device *dev = &dev_dax->dev;
 	phys_addr_t phys;
 	pgoff_t pgoff;
-	pfn_t pfn;
+	unsigned long pfn;
 	unsigned int fault_size = PMD_SIZE;
 
 	if (check_vma(dev_dax, vmf->vma, __func__))
@@ -169,11 +168,11 @@ static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
 		return VM_FAULT_SIGBUS;
 	}
 
-	pfn = phys_to_pfn_t(phys, 0);
+	pfn = PHYS_PFN(phys);
 
 	dax_set_mapping(vmf, pfn, fault_size);
 
-	return vmf_insert_folio_pmd(vmf, page_folio(pfn_t_to_page(pfn)),
+	return vmf_insert_folio_pmd(vmf, page_folio(pfn_to_page(pfn)),
 				vmf->flags & FAULT_FLAG_WRITE);
 }
 
@@ -185,7 +184,7 @@ static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
 	struct device *dev = &dev_dax->dev;
 	phys_addr_t phys;
 	pgoff_t pgoff;
-	pfn_t pfn;
+	unsigned long pfn;
 	unsigned int fault_size = PUD_SIZE;
 
 
@@ -215,11 +214,11 @@ static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
 		return VM_FAULT_SIGBUS;
 	}
 
-	pfn = phys_to_pfn_t(phys, 0);
+	pfn = PHYS_PFN(phys);
 
 	dax_set_mapping(vmf, pfn, fault_size);
 
-	return vmf_insert_folio_pud(vmf, page_folio(pfn_t_to_page(pfn)),
+	return vmf_insert_folio_pud(vmf, page_folio(pfn_to_page(pfn)),
 				vmf->flags & FAULT_FLAG_WRITE);
 }
 #else
diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index 5e7c53f..c18451a 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -2,7 +2,6 @@
 #include <linux/platform_device.h>
 #include <linux/memregion.h>
 #include <linux/module.h>
-#include <linux/pfn_t.h>
 #include <linux/dax.h>
 #include "../bus.h"
 
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index e97d47f..87b5321 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -5,7 +5,6 @@
 #include <linux/memory.h>
 #include <linux/module.h>
 #include <linux/device.h>
-#include <linux/pfn_t.h>
 #include <linux/slab.h>
 #include <linux/dax.h>
 #include <linux/fs.h>
diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
index c8ebf4e..bee9306 100644
--- a/drivers/dax/pmem.c
+++ b/drivers/dax/pmem.c
@@ -2,7 +2,6 @@
 /* Copyright(c) 2016 - 2018 Intel Corporation. All rights reserved. */
 #include <linux/memremap.h>
 #include <linux/module.h>
-#include <linux/pfn_t.h>
 #include "../nvdimm/pfn.h"
 #include "../nvdimm/nd.h"
 #include "bus.h"
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index e16d1d4..54c480e 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -7,7 +7,6 @@
 #include <linux/mount.h>
 #include <linux/pseudo_fs.h>
 #include <linux/magic.h>
-#include <linux/pfn_t.h>
 #include <linux/cdev.h>
 #include <linux/slab.h>
 #include <linux/uio.h>
@@ -148,7 +147,7 @@ enum dax_device_flags {
  * pages accessible at the device relative @pgoff.
  */
 long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
-		enum dax_access_mode mode, void **kaddr, pfn_t *pfn)
+		enum dax_access_mode mode, void **kaddr, unsigned long *pfn)
 {
 	long avail;
 
diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 4787fee..84b2172 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -7,7 +7,6 @@
 
 
 #include <linux/dma-buf.h>
-#include <linux/pfn_t.h>
 #include <linux/shmem_fs.h>
 #include <linux/module.h>
 
diff --git a/drivers/gpu/drm/gma500/fbdev.c b/drivers/gpu/drm/gma500/fbdev.c
index 109efdc..68b825f 100644
--- a/drivers/gpu/drm/gma500/fbdev.c
+++ b/drivers/gpu/drm/gma500/fbdev.c
@@ -6,7 +6,6 @@
  **************************************************************************/
 
 #include <linux/fb.h>
-#include <linux/pfn_t.h>
 
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_drv.h>
@@ -33,7 +32,7 @@ static vm_fault_t psb_fbdev_vm_fault(struct vm_fault *vmf)
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 
 	for (i = 0; i < page_num; ++i) {
-		err = vmf_insert_mixed(vma, address, __pfn_to_pfn_t(pfn, 0));
+		err = vmf_insert_mixed(vma, address, pfn);
 		if (unlikely(err & VM_FAULT_ERROR))
 			break;
 		address += PAGE_SIZE;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index c3dabb8..52fb78d 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -6,7 +6,6 @@
 
 #include <linux/anon_inodes.h>
 #include <linux/mman.h>
-#include <linux/pfn_t.h>
 #include <linux/sizes.h>
 
 #include <drm/drm_cache.h>
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index ebc9ba6..1c27500 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -9,7 +9,6 @@
 #include <linux/spinlock.h>
 #include <linux/shmem_fs.h>
 #include <linux/dma-buf.h>
-#include <linux/pfn_t.h>
 
 #include <drm/drm_prime.h>
 #include <drm/drm_file.h>
diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index 9df05b2..381552b 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -8,7 +8,6 @@
 #include <linux/seq_file.h>
 #include <linux/shmem_fs.h>
 #include <linux/spinlock.h>
-#include <linux/pfn_t.h>
 #include <linux/vmalloc.h>
 
 #include <drm/drm_prime.h>
@@ -371,7 +370,7 @@ static vm_fault_t omap_gem_fault_1d(struct drm_gem_object *obj,
 	VERB("Inserting %p pfn %lx, pa %lx", (void *)vmf->address,
 			pfn, pfn << PAGE_SHIFT);
 
-	return vmf_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, 0));
+	return vmf_insert_mixed(vma, vmf->address, pfn);
 }
 
 /* Special handling for the case of faulting in 2d tiled buffers */
@@ -466,8 +465,7 @@ static vm_fault_t omap_gem_fault_2d(struct drm_gem_object *obj,
 			pfn, pfn << PAGE_SHIFT);
 
 	for (i = n; i > 0; i--) {
-		ret = vmf_insert_mixed(vma,
-			vaddr, __pfn_to_pfn_t(pfn, 0));
+		ret = vmf_insert_mixed(vma, vaddr, pfn);
 		if (ret & VM_FAULT_ERROR)
 			break;
 		pfn += priv->usergart[fmt].stride_pfn;
diff --git a/drivers/gpu/drm/v3d/v3d_bo.c b/drivers/gpu/drm/v3d/v3d_bo.c
index bb78155..c41476d 100644
--- a/drivers/gpu/drm/v3d/v3d_bo.c
+++ b/drivers/gpu/drm/v3d/v3d_bo.c
@@ -16,7 +16,6 @@
  */
 
 #include <linux/dma-buf.h>
-#include <linux/pfn_t.h>
 #include <linux/vmalloc.h>
 
 #include "v3d_drv.h"
diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c
index 7163950..f3a13b3 100644
--- a/drivers/hwtracing/intel_th/msu.c
+++ b/drivers/hwtracing/intel_th/msu.c
@@ -19,7 +19,6 @@
 #include <linux/io.h>
 #include <linux/workqueue.h>
 #include <linux/dma-mapping.h>
-#include <linux/pfn_t.h>
 
 #ifdef CONFIG_X86
 #include <asm/set_memory.h>
@@ -1618,7 +1617,7 @@ static vm_fault_t msc_mmap_fault(struct vm_fault *vmf)
 		return VM_FAULT_SIGBUS;
 
 	get_page(page);
-	return vmf_insert_mixed(vmf->vma, vmf->address, page_to_pfn_t(page));
+	return vmf_insert_mixed(vmf->vma, vmf->address, page_to_pfn(page));
 }
 
 static const struct vm_operations_struct msc_mmap_ops = {
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 66318ab..bc2f163 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -168,7 +168,7 @@ static struct dax_device *linear_dax_pgoff(struct dm_target *ti, pgoff_t *pgoff)
 
 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 		long nr_pages, enum dax_access_mode mode, void **kaddr,
-		pfn_t *pfn)
+		unsigned long *pfn)
 {
 	struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
 
diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index 8d7df83..4c6aed7 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -891,7 +891,7 @@ static struct dax_device *log_writes_dax_pgoff(struct dm_target *ti,
 
 static long log_writes_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 		long nr_pages, enum dax_access_mode mode, void **kaddr,
-		pfn_t *pfn)
+		unsigned long *pfn)
 {
 	struct dax_device *dax_dev = log_writes_dax_pgoff(ti, &pgoff);
 
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index a1b7535..d554cf1 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -316,7 +316,7 @@ static struct dax_device *stripe_dax_pgoff(struct dm_target *ti, pgoff_t *pgoff)
 
 static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 		long nr_pages, enum dax_access_mode mode, void **kaddr,
-		pfn_t *pfn)
+		unsigned long *pfn)
 {
 	struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
 
diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index 652627a..2af5a95 100644
--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -255,7 +255,7 @@ static void io_err_io_hints(struct dm_target *ti, struct queue_limits *limits)
 
 static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 		long nr_pages, enum dax_access_mode mode, void **kaddr,
-		pfn_t *pfn)
+		unsigned long *pfn)
 {
 	return -EIO;
 }
diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index d6a04a5..98f0c43 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -13,7 +13,6 @@
 #include <linux/dm-io.h>
 #include <linux/dm-kcopyd.h>
 #include <linux/dax.h>
-#include <linux/pfn_t.h>
 #include <linux/libnvdimm.h>
 #include <linux/delay.h>
 #include "dm-io-tracker.h"
@@ -256,7 +255,7 @@ static int persistent_memory_claim(struct dm_writecache *wc)
 	int r;
 	loff_t s;
 	long p, da;
-	pfn_t pfn;
+	unsigned long pfn;
 	int id;
 	struct page **pages;
 	sector_t offset;
@@ -290,7 +289,7 @@ static int persistent_memory_claim(struct dm_writecache *wc)
 		r = da;
 		goto err2;
 	}
-	if (!pfn_t_has_page(pfn)) {
+	if (!pfn_valid(pfn)) {
 		wc->memory_map = NULL;
 		r = -EOPNOTSUPP;
 		goto err2;
@@ -314,13 +313,13 @@ static int persistent_memory_claim(struct dm_writecache *wc)
 				r = daa ? daa : -EINVAL;
 				goto err3;
 			}
-			if (!pfn_t_has_page(pfn)) {
+			if (!pfn_valid(pfn)) {
 				r = -EOPNOTSUPP;
 				goto err3;
 			}
 			while (daa-- && i < p) {
-				pages[i++] = pfn_t_to_page(pfn);
-				pfn.val++;
+				pages[i++] = pfn_to_page(pfn);
+				pfn++;
 				if (!(i & 15))
 					cond_resched();
 			}
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 5ab7574..dab026b 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1232,7 +1232,7 @@ static struct dm_target *dm_dax_get_live_target(struct mapped_device *md,
 
 static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 		long nr_pages, enum dax_access_mode mode, void **kaddr,
-		pfn_t *pfn)
+		unsigned long *pfn)
 {
 	struct mapped_device *md = dax_get_private(dax_dev);
 	sector_t sector = pgoff * PAGE_SECTORS;
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index aa50006..05785ff 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -20,7 +20,6 @@
 #include <linux/kstrtox.h>
 #include <linux/vmalloc.h>
 #include <linux/blk-mq.h>
-#include <linux/pfn_t.h>
 #include <linux/slab.h>
 #include <linux/uio.h>
 #include <linux/dax.h>
@@ -242,7 +241,7 @@ static void pmem_submit_bio(struct bio *bio)
 /* see "strong" declaration in tools/testing/nvdimm/pmem-dax.c */
 __weak long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 		long nr_pages, enum dax_access_mode mode, void **kaddr,
-		pfn_t *pfn)
+		unsigned long *pfn)
 {
 	resource_size_t offset = PFN_PHYS(pgoff) + pmem->data_offset;
 	sector_t sector = PFN_PHYS(pgoff) >> SECTOR_SHIFT;
@@ -254,7 +253,7 @@ __weak long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 	if (kaddr)
 		*kaddr = pmem->virt_addr + offset;
 	if (pfn)
-		*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
+		*pfn = PHYS_PFN(pmem->phys_addr + offset);
 
 	if (bb->count &&
 	    badblocks_check(bb, sector, num, &first_bad, &num_bad)) {
@@ -303,7 +302,7 @@ static int pmem_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
 
 static long pmem_dax_direct_access(struct dax_device *dax_dev,
 		pgoff_t pgoff, long nr_pages, enum dax_access_mode mode,
-		void **kaddr, pfn_t *pfn)
+		void **kaddr, unsigned long *pfn)
 {
 	struct pmem_device *pmem = dax_get_private(dax_dev);
 
@@ -513,7 +512,6 @@ static int pmem_attach_disk(struct device *dev,
 
 	pmem->disk = disk;
 	pmem->pgmap.owner = pmem;
-	pmem->pfn_flags = 0;
 	if (is_nd_pfn(dev)) {
 		pmem->pgmap.type = MEMORY_DEVICE_FS_DAX;
 		pmem->pgmap.ops = &fsdax_pagemap_ops;
diff --git a/drivers/nvdimm/pmem.h b/drivers/nvdimm/pmem.h
index 392b0b3..a48509f 100644
--- a/drivers/nvdimm/pmem.h
+++ b/drivers/nvdimm/pmem.h
@@ -5,7 +5,6 @@
 #include <linux/badblocks.h>
 #include <linux/memremap.h>
 #include <linux/types.h>
-#include <linux/pfn_t.h>
 #include <linux/fs.h>
 
 enum dax_access_mode;
@@ -16,7 +15,6 @@ struct pmem_device {
 	phys_addr_t		phys_addr;
 	/* when non-zero this device is hosting a 'pfn' instance */
 	phys_addr_t		data_offset;
-	u64			pfn_flags;
 	void			*virt_addr;
 	/* immutable base size of the namespace */
 	size_t			size;
@@ -31,7 +29,7 @@ struct pmem_device {
 
 long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 		long nr_pages, enum dax_access_mode mode, void **kaddr,
-		pfn_t *pfn);
+		unsigned long *pfn);
 
 #ifdef CONFIG_MEMORY_FAILURE
 static inline bool test_and_clear_pmem_poison(struct page *page)
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 02d7a21..1dee7e8 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -17,7 +17,6 @@
 #include <linux/blkdev.h>
 #include <linux/completion.h>
 #include <linux/interrupt.h>
-#include <linux/pfn_t.h>
 #include <linux/uio.h>
 #include <linux/dax.h>
 #include <linux/io.h>
@@ -33,7 +32,7 @@ static void dcssblk_release(struct gendisk *disk);
 static void dcssblk_submit_bio(struct bio *bio);
 static long dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 		long nr_pages, enum dax_access_mode mode, void **kaddr,
-		pfn_t *pfn);
+		unsigned long *pfn);
 
 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
 
@@ -914,7 +913,7 @@ dcssblk_submit_bio(struct bio *bio)
 
 static long
 __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
-		long nr_pages, void **kaddr, pfn_t *pfn)
+		long nr_pages, void **kaddr, unsigned long *pfn)
 {
 	resource_size_t offset = pgoff * PAGE_SIZE;
 	unsigned long dev_sz;
@@ -923,7 +922,7 @@ __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 	if (kaddr)
 		*kaddr = __va(dev_info->start + offset);
 	if (pfn)
-		*pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), 0);
+		*pfn = PFN_DOWN(dev_info->start + offset);
 
 	return (dev_sz - offset) / PAGE_SIZE;
 }
@@ -931,7 +930,7 @@ __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
 static long
 dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 		long nr_pages, enum dax_access_mode mode, void **kaddr,
-		pfn_t *pfn)
+		unsigned long *pfn)
 {
 	struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 3f2ad5f..31bdb91 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -20,7 +20,6 @@
 #include <linux/mutex.h>
 #include <linux/notifier.h>
 #include <linux/pci.h>
-#include <linux/pfn_t.h>
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/types.h>
@@ -1669,12 +1668,12 @@ static vm_fault_t vfio_pci_mmap_huge_fault(struct vm_fault *vmf,
 		break;
 #ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
 	case PMD_ORDER:
-		ret = vmf_insert_pfn_pmd(vmf, __pfn_to_pfn_t(pfn, 0), false);
+		ret = vmf_insert_pfn_pmd(vmf, pfn, false);
 		break;
 #endif
 #ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
 	case PUD_ORDER:
-		ret = vmf_insert_pfn_pud(vmf, __pfn_to_pfn_t(pfn, 0), false);
+		ret = vmf_insert_pfn_pud(vmf, pfn, false);
 		break;
 #endif
 	default:
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index 820a664..b002e9b 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -17,7 +17,6 @@
 #include <linux/fs.h>
 #include <linux/file.h>
 #include <linux/pagemap.h>
-#include <linux/pfn_t.h>
 #include <linux/ramfs.h>
 #include <linux/init.h>
 #include <linux/string.h>
@@ -412,8 +411,8 @@ static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
 		for (i = 0; i < pages && !ret; i++) {
 			vm_fault_t vmf;
 			unsigned long off = i * PAGE_SIZE;
-			pfn_t pfn = phys_to_pfn_t(address + off, 0);
-			vmf = vmf_insert_mixed(vma, vma->vm_start + off, pfn);
+			vmf = vmf_insert_mixed(vma, vma->vm_start + off,
+					address + off);
 			if (vmf & VM_FAULT_ERROR)
 				ret = vm_fault_to_errno(vmf, 0);
 		}
diff --git a/fs/dax.c b/fs/dax.c
index 206dbd0..67bb647 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -20,7 +20,6 @@
 #include <linux/sched/signal.h>
 #include <linux/uio.h>
 #include <linux/vmstat.h>
-#include <linux/pfn_t.h>
 #include <linux/sizes.h>
 #include <linux/mmu_notifier.h>
 #include <linux/iomap.h>
@@ -76,9 +75,9 @@ static struct folio *dax_to_folio(void *entry)
 	return page_folio(pfn_to_page(dax_to_pfn(entry)));
 }
 
-static void *dax_make_entry(pfn_t pfn, unsigned long flags)
+static void *dax_make_entry(unsigned long pfn, unsigned long flags)
 {
-	return xa_mk_value(flags | (pfn_t_to_pfn(pfn) << DAX_SHIFT));
+	return xa_mk_value(flags | (pfn << DAX_SHIFT));
 }
 
 static bool dax_is_locked(void *entry)
@@ -719,7 +718,7 @@ static void *grab_mapping_entry(struct xa_state *xas,
 
 		if (order > 0)
 			flags |= DAX_PMD;
-		entry = dax_make_entry(pfn_to_pfn_t(0), flags);
+		entry = dax_make_entry(0, flags);
 		dax_lock_entry(xas, entry);
 		if (xas_error(xas))
 			goto out_unlock;
@@ -1053,7 +1052,7 @@ static bool dax_fault_is_synchronous(const struct iomap_iter *iter,
  * appropriate.
  */
 static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf,
-		const struct iomap_iter *iter, void *entry, pfn_t pfn,
+		const struct iomap_iter *iter, void *entry, unsigned long pfn,
 		unsigned long flags)
 {
 	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
@@ -1251,7 +1250,7 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
 
 static int dax_iomap_direct_access(const struct iomap *iomap, loff_t pos,
-		size_t size, void **kaddr, pfn_t *pfnp)
+		size_t size, void **kaddr, unsigned long *pfnp)
 {
 	pgoff_t pgoff = dax_iomap_pgoff(iomap, pos);
 	int id, rc = 0;
@@ -1269,7 +1268,7 @@ static int dax_iomap_direct_access(const struct iomap *iomap, loff_t pos,
 	rc = -EINVAL;
 	if (PFN_PHYS(length) < size)
 		goto out;
-	if (pfn_t_to_pfn(*pfnp) & (PHYS_PFN(size)-1))
+	if (*pfnp & (PHYS_PFN(size)-1))
 		goto out;
 
 	rc = 0;
@@ -1373,12 +1372,12 @@ static vm_fault_t dax_load_hole(struct xa_state *xas, struct vm_fault *vmf,
 {
 	struct inode *inode = iter->inode;
 	unsigned long vaddr = vmf->address;
-	pfn_t pfn = pfn_to_pfn_t(my_zero_pfn(vaddr));
+	unsigned long pfn = my_zero_pfn(vaddr);
 	vm_fault_t ret;
 
 	*entry = dax_insert_entry(xas, vmf, iter, *entry, pfn, DAX_ZERO_PAGE);
 
-	ret = vmf_insert_page_mkwrite(vmf, pfn_t_to_page(pfn), false);
+	ret = vmf_insert_page_mkwrite(vmf, pfn_to_page(pfn), false);
 	trace_dax_load_hole(inode, vmf, ret);
 	return ret;
 }
@@ -1395,14 +1394,14 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
 	struct folio *zero_folio;
 	spinlock_t *ptl;
 	pmd_t pmd_entry;
-	pfn_t pfn;
+	unsigned long pfn;
 
 	zero_folio = mm_get_huge_zero_folio(vmf->vma->vm_mm);
 
 	if (unlikely(!zero_folio))
 		goto fallback;
 
-	pfn = page_to_pfn_t(&zero_folio->page);
+	pfn = page_to_pfn(&zero_folio->page);
 	*entry = dax_insert_entry(xas, vmf, iter, *entry, pfn,
 				  DAX_PMD | DAX_ZERO_PAGE);
 
@@ -1792,7 +1791,8 @@ static vm_fault_t dax_fault_return(int error)
  * insertion for now and return the pfn so that caller can insert it after the
  * fsync is done.
  */
-static vm_fault_t dax_fault_synchronous_pfnp(pfn_t *pfnp, pfn_t pfn)
+static vm_fault_t dax_fault_synchronous_pfnp(unsigned long *pfnp,
+					unsigned long pfn)
 {
 	if (WARN_ON_ONCE(!pfnp))
 		return VM_FAULT_SIGBUS;
@@ -1840,7 +1840,7 @@ static vm_fault_t dax_fault_cow_page(struct vm_fault *vmf,
  * @pmd:	distinguish whether it is a pmd fault
  */
 static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
-		const struct iomap_iter *iter, pfn_t *pfnp,
+		const struct iomap_iter *iter, unsigned long *pfnp,
 		struct xa_state *xas, void **entry, bool pmd)
 {
 	const struct iomap *iomap = &iter->iomap;
@@ -1851,7 +1851,7 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
 	unsigned long entry_flags = pmd ? DAX_PMD : 0;
 	struct folio *folio;
 	int ret, err = 0;
-	pfn_t pfn;
+	unsigned long pfn;
 	void *kaddr;
 
 	if (!pmd && vmf->cow_page)
@@ -1888,16 +1888,15 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
 
 	folio_ref_inc(folio);
 	if (pmd)
-		ret = vmf_insert_folio_pmd(vmf, pfn_folio(pfn_t_to_pfn(pfn)),
-					write);
+		ret = vmf_insert_folio_pmd(vmf, pfn_folio(pfn), write);
 	else
-		ret = vmf_insert_page_mkwrite(vmf, pfn_t_to_page(pfn), write);
+		ret = vmf_insert_page_mkwrite(vmf, pfn_to_page(pfn), write);
 	folio_put(folio);
 
 	return ret;
 }
 
-static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
+static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, unsigned long *pfnp,
 			       int *iomap_errp, const struct iomap_ops *ops)
 {
 	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
@@ -2009,7 +2008,7 @@ static bool dax_fault_check_fallback(struct vm_fault *vmf, struct xa_state *xas,
 	return false;
 }
 
-static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
+static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, unsigned long *pfnp,
 			       const struct iomap_ops *ops)
 {
 	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
@@ -2090,7 +2089,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	return ret;
 }
 #else
-static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
+static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, unsigned long *pfnp,
 			       const struct iomap_ops *ops)
 {
 	return VM_FAULT_FALLBACK;
@@ -2111,7 +2110,8 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
  * successfully.
  */
 vm_fault_t dax_iomap_fault(struct vm_fault *vmf, unsigned int order,
-		    pfn_t *pfnp, int *iomap_errp, const struct iomap_ops *ops)
+			unsigned long *pfnp, int *iomap_errp,
+			const struct iomap_ops *ops)
 {
 	if (order == 0)
 		return dax_iomap_pte_fault(vmf, pfnp, iomap_errp, ops);
@@ -2131,8 +2131,8 @@ EXPORT_SYMBOL_GPL(dax_iomap_fault);
  * This function inserts a writeable PTE or PMD entry into the page tables
  * for an mmaped DAX file.  It also marks the page cache entry as dirty.
  */
-static vm_fault_t
-dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order)
+static vm_fault_t dax_insert_pfn_mkwrite(struct vm_fault *vmf,
+					unsigned long pfn, unsigned int order)
 {
 	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
 	XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, order);
@@ -2154,7 +2154,7 @@ dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order)
 	xas_set_mark(&xas, PAGECACHE_TAG_DIRTY);
 	dax_lock_entry(&xas, entry);
 	xas_unlock_irq(&xas);
-	folio = pfn_folio(pfn_t_to_pfn(pfn));
+	folio = pfn_folio(pfn);
 	folio_ref_inc(folio);
 	if (order == 0)
 		ret = vmf_insert_page_mkwrite(vmf, &folio->page, true);
@@ -2181,7 +2181,7 @@ dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order)
  * table entry.
  */
 vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf, unsigned int order,
-		pfn_t pfn)
+		unsigned long pfn)
 {
 	int err;
 	loff_t start = ((loff_t)vmf->pgoff) << PAGE_SHIFT;
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index beb078e..6167d03 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -742,7 +742,7 @@ static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf, unsigned int order)
 	bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
 		(vmf->vma->vm_flags & VM_SHARED);
 	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
-	pfn_t pfn;
+	unsigned long pfn;
 
 	if (write) {
 		sb_start_pagefault(sb);
diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
index 0502bf3..ac6d4c1 100644
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -10,7 +10,6 @@
 #include <linux/dax.h>
 #include <linux/uio.h>
 #include <linux/pagemap.h>
-#include <linux/pfn_t.h>
 #include <linux/iomap.h>
 #include <linux/interval_tree.h>
 
@@ -757,7 +756,7 @@ static vm_fault_t __fuse_dax_fault(struct vm_fault *vmf, unsigned int order,
 	vm_fault_t ret;
 	struct inode *inode = file_inode(vmf->vma->vm_file);
 	struct super_block *sb = inode->i_sb;
-	pfn_t pfn;
+	unsigned long pfn;
 	int error = 0;
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_conn_dax *fcd = fc->dax;
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 53c2626..aac914b 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -9,7 +9,6 @@
 #include <linux/pci.h>
 #include <linux/interrupt.h>
 #include <linux/group_cpus.h>
-#include <linux/pfn_t.h>
 #include <linux/memremap.h>
 #include <linux/module.h>
 #include <linux/virtio.h>
@@ -1008,7 +1007,7 @@ static void virtio_fs_cleanup_vqs(struct virtio_device *vdev)
  */
 static long virtio_fs_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 				    long nr_pages, enum dax_access_mode mode,
-				    void **kaddr, pfn_t *pfn)
+				    void **kaddr, unsigned long *pfn)
 {
 	struct virtio_fs *fs = dax_get_private(dax_dev);
 	phys_addr_t offset = PFN_PHYS(pgoff);
@@ -1017,7 +1016,7 @@ static long virtio_fs_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 	if (kaddr)
 		*kaddr = fs->window_kaddr + offset;
 	if (pfn)
-		*pfn = phys_to_pfn_t(fs->window_phys_addr + offset, 0);
+		*pfn = fs->window_phys_addr + offset;
 	return nr_pages > max_nr_pages ? max_nr_pages : nr_pages;
 }
 
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 84f08c9..3ac2a1f 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1660,7 +1660,7 @@ xfs_dax_fault_locked(
 	bool			write_fault)
 {
 	vm_fault_t		ret;
-	pfn_t			pfn;
+	unsigned long		pfn;
 
 	if (!IS_ENABLED(CONFIG_FS_DAX)) {
 		ASSERT(0);
diff --git a/include/linux/dax.h b/include/linux/dax.h
index dcc9fcd..29eec75 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -26,7 +26,7 @@ struct dax_operations {
 	 * number of pages available for DAX at that pfn.
 	 */
 	long (*direct_access)(struct dax_device *, pgoff_t, long,
-			enum dax_access_mode, void **, pfn_t *);
+			enum dax_access_mode, void **, unsigned long *);
 	/* zero_page_range: required operation. Zero page range   */
 	int (*zero_page_range)(struct dax_device *, pgoff_t, size_t);
 	/*
@@ -241,7 +241,7 @@ static inline void dax_break_layout_final(struct inode *inode)
 bool dax_alive(struct dax_device *dax_dev);
 void *dax_get_private(struct dax_device *dax_dev);
 long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
-		enum dax_access_mode mode, void **kaddr, pfn_t *pfn);
+		enum dax_access_mode mode, void **kaddr, unsigned long *pfn);
 size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
 		size_t bytes, struct iov_iter *i);
 size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
@@ -255,9 +255,10 @@ void dax_flush(struct dax_device *dax_dev, void *addr, size_t size);
 ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
 		const struct iomap_ops *ops);
 vm_fault_t dax_iomap_fault(struct vm_fault *vmf, unsigned int order,
-		    pfn_t *pfnp, int *errp, const struct iomap_ops *ops);
+			unsigned long *pfnp, int *errp,
+			const struct iomap_ops *ops);
 vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
-		unsigned int order, pfn_t pfn);
+		unsigned int order, unsigned long pfn);
 int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
 void dax_delete_mapping_range(struct address_space *mapping,
 				loff_t start, loff_t end);
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index bcc6d7b..692e4c0 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -149,7 +149,7 @@ typedef int (*dm_busy_fn) (struct dm_target *ti);
  */
 typedef long (*dm_dax_direct_access_fn) (struct dm_target *ti, pgoff_t pgoff,
 		long nr_pages, enum dax_access_mode node, void **kaddr,
-		pfn_t *pfn);
+		unsigned long *pfn);
 typedef int (*dm_dax_zero_page_range_fn)(struct dm_target *ti, pgoff_t pgoff,
 		size_t nr_pages);
 
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 374daa8..dc6ace2 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -37,8 +37,10 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		    pmd_t *pmd, unsigned long addr, pgprot_t newprot,
 		    unsigned long cp_flags);
 
-vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write);
-vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write);
+vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, unsigned long pfn,
+			      bool write);
+vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, unsigned long pfn,
+			      bool write);
 vm_fault_t vmf_insert_folio_pmd(struct vm_fault *vmf, struct folio *folio,
 				bool write);
 vm_fault_t vmf_insert_folio_pud(struct vm_fault *vmf, struct folio *folio,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c5345ee..12d9665 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3644,9 +3644,9 @@ vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 			unsigned long pfn, pgprot_t pgprot);
 vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
-			pfn_t pfn);
+			unsigned long pfn);
 vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
-		unsigned long addr, pfn_t pfn);
+		unsigned long addr, unsigned long pfn);
 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
 
 static inline vm_fault_t vmf_insert_page(struct vm_area_struct *vma,
diff --git a/include/linux/pfn.h b/include/linux/pfn.h
index 14bc053..b90ca0b 100644
--- a/include/linux/pfn.h
+++ b/include/linux/pfn.h
@@ -4,15 +4,6 @@
 
 #ifndef __ASSEMBLY__
 #include <linux/types.h>
-
-/*
- * pfn_t: encapsulates a page-frame number that is optionally backed
- * by memmap (struct page).  Whether a pfn_t has a 'struct page'
- * backing is indicated by flags in the high bits of the value.
- */
-typedef struct {
-	u64 val;
-} pfn_t;
 #endif
 
 #define PFN_ALIGN(x)	(((unsigned long)(x) + (PAGE_SIZE - 1)) & PAGE_MASK)
diff --git a/include/linux/pfn_t.h b/include/linux/pfn_t.h
deleted file mode 100644
index be8c174..0000000
--- a/include/linux/pfn_t.h
+++ /dev/null
@@ -1,85 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _LINUX_PFN_T_H_
-#define _LINUX_PFN_T_H_
-#include <linux/mm.h>
-
-/*
- * PFN_FLAGS_MASK - mask of all the possible valid pfn_t flags
- * PFN_DEV - pfn is not covered by system memmap by default
- */
-#define PFN_FLAGS_MASK (((u64) (~PAGE_MASK)) << (BITS_PER_LONG_LONG - PAGE_SHIFT))
-
-#define PFN_FLAGS_TRACE { }
-
-static inline pfn_t __pfn_to_pfn_t(unsigned long pfn, u64 flags)
-{
-	pfn_t pfn_t = { .val = pfn | (flags & PFN_FLAGS_MASK), };
-
-	return pfn_t;
-}
-
-/* a default pfn to pfn_t conversion assumes that @pfn is pfn_valid() */
-static inline pfn_t pfn_to_pfn_t(unsigned long pfn)
-{
-	return __pfn_to_pfn_t(pfn, 0);
-}
-
-static inline pfn_t phys_to_pfn_t(phys_addr_t addr, u64 flags)
-{
-	return __pfn_to_pfn_t(addr >> PAGE_SHIFT, flags);
-}
-
-static inline bool pfn_t_has_page(pfn_t pfn)
-{
-	return true;
-}
-
-static inline unsigned long pfn_t_to_pfn(pfn_t pfn)
-{
-	return pfn.val & ~PFN_FLAGS_MASK;
-}
-
-static inline struct page *pfn_t_to_page(pfn_t pfn)
-{
-	if (pfn_t_has_page(pfn))
-		return pfn_to_page(pfn_t_to_pfn(pfn));
-	return NULL;
-}
-
-static inline phys_addr_t pfn_t_to_phys(pfn_t pfn)
-{
-	return PFN_PHYS(pfn_t_to_pfn(pfn));
-}
-
-static inline pfn_t page_to_pfn_t(struct page *page)
-{
-	return pfn_to_pfn_t(page_to_pfn(page));
-}
-
-static inline int pfn_t_valid(pfn_t pfn)
-{
-	return pfn_valid(pfn_t_to_pfn(pfn));
-}
-
-#ifdef CONFIG_MMU
-static inline pte_t pfn_t_pte(pfn_t pfn, pgprot_t pgprot)
-{
-	return pfn_pte(pfn_t_to_pfn(pfn), pgprot);
-}
-#endif
-
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-static inline pmd_t pfn_t_pmd(pfn_t pfn, pgprot_t pgprot)
-{
-	return pfn_pmd(pfn_t_to_pfn(pfn), pgprot);
-}
-
-#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
-static inline pud_t pfn_t_pud(pfn_t pfn, pgprot_t pgprot)
-{
-	return pfn_pud(pfn_t_to_pfn(pfn), pgprot);
-}
-#endif
-#endif
-
-#endif /* _LINUX_PFN_T_H_ */
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index ed3317e..cc56485 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1505,7 +1505,7 @@ static inline int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
  * by vmf_insert_pfn().
  */
 static inline void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
-				    pfn_t pfn)
+				    unsigned long pfn)
 {
 }
 
@@ -1557,7 +1557,7 @@ extern int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
 			   unsigned long pfn, unsigned long addr,
 			   unsigned long size);
 extern void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
-			     pfn_t pfn);
+			     unsigned long pfn);
 extern int track_pfn_copy(struct vm_area_struct *dst_vma,
 		struct vm_area_struct *src_vma, unsigned long *pfn);
 extern void untrack_pfn_copy(struct vm_area_struct *dst_vma,
diff --git a/include/trace/events/fs_dax.h b/include/trace/events/fs_dax.h
index 86fe6ae..1af7e2e 100644
--- a/include/trace/events/fs_dax.h
+++ b/include/trace/events/fs_dax.h
@@ -104,7 +104,7 @@ DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole_fallback);
 
 DECLARE_EVENT_CLASS(dax_pmd_insert_mapping_class,
 	TP_PROTO(struct inode *inode, struct vm_fault *vmf,
-		long length, pfn_t pfn, void *radix_entry),
+		long length, unsigned long pfn, void *radix_entry),
 	TP_ARGS(inode, vmf, length, pfn, radix_entry),
 	TP_STRUCT__entry(
 		__field(unsigned long, ino)
@@ -123,11 +123,11 @@ DECLARE_EVENT_CLASS(dax_pmd_insert_mapping_class,
 		__entry->address = vmf->address;
 		__entry->write = vmf->flags & FAULT_FLAG_WRITE;
 		__entry->length = length;
-		__entry->pfn_val = pfn.val;
+		__entry->pfn_val = pfn;
 		__entry->radix_entry = radix_entry;
 	),
 	TP_printk("dev %d:%d ino %#lx %s %s address %#lx length %#lx "
-			"pfn %#llx %s radix_entry %#lx",
+			"pfn %#llx radix_entry %#lx",
 		MAJOR(__entry->dev),
 		MINOR(__entry->dev),
 		__entry->ino,
@@ -135,9 +135,7 @@ DECLARE_EVENT_CLASS(dax_pmd_insert_mapping_class,
 		__entry->write ? "write" : "read",
 		__entry->address,
 		__entry->length,
-		__entry->pfn_val & ~PFN_FLAGS_MASK,
-		__print_flags_u64(__entry->pfn_val & PFN_FLAGS_MASK, "|",
-			PFN_FLAGS_TRACE),
+		__entry->pfn_val,
 		(unsigned long)__entry->radix_entry
 	)
 )
@@ -145,7 +143,7 @@ DECLARE_EVENT_CLASS(dax_pmd_insert_mapping_class,
 #define DEFINE_PMD_INSERT_MAPPING_EVENT(name) \
 DEFINE_EVENT(dax_pmd_insert_mapping_class, name, \
 	TP_PROTO(struct inode *inode, struct vm_fault *vmf, \
-		long length, pfn_t pfn, void *radix_entry), \
+		long length, unsigned long pfn, void *radix_entry), \
 	TP_ARGS(inode, vmf, length, pfn, radix_entry))
 
 DEFINE_PMD_INSERT_MAPPING_EVENT(dax_pmd_insert_mapping);
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index cf5ff92..a0e5d01 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -20,7 +20,6 @@
 #include <linux/mman.h>
 #include <linux/mm_types.h>
 #include <linux/module.h>
-#include <linux/pfn_t.h>
 #include <linux/printk.h>
 #include <linux/pgtable.h>
 #include <linux/random.h>
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 31b4110..3ba6dfc 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -22,7 +22,6 @@
 #include <linux/mm_types.h>
 #include <linux/khugepaged.h>
 #include <linux/freezer.h>
-#include <linux/pfn_t.h>
 #include <linux/mman.h>
 #include <linux/memremap.h>
 #include <linux/pagemap.h>
@@ -1374,7 +1373,7 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 }
 
 static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
-		pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
+		pmd_t *pmd, unsigned long pfn, pgprot_t prot, bool write,
 		pgtable_t pgtable)
 {
 	struct mm_struct *mm = vma->vm_mm;
@@ -1384,7 +1383,7 @@ static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 
 	if (!pmd_none(*pmd)) {
 		if (write) {
-			if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
+			if (pmd_pfn(*pmd) != pfn) {
 				WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
 				return -EEXIST;
 			}
@@ -1397,7 +1396,7 @@ static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 		return -EEXIST;
 	}
 
-	entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
+	entry = pmd_mkhuge(pfn_pmd(pfn, prot));
 	entry = pmd_mkspecial(entry);
 	if (write) {
 		entry = pmd_mkyoung(pmd_mkdirty(entry));
@@ -1424,7 +1423,8 @@ static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
  *
  * Return: vm_fault_t value.
  */
-vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
+vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, unsigned long pfn,
+			      bool write)
 {
 	unsigned long addr = vmf->address & PMD_MASK;
 	struct vm_area_struct *vma = vmf->vma;
@@ -1491,9 +1491,8 @@ vm_fault_t vmf_insert_folio_pmd(struct vm_fault *vmf, struct folio *folio,
 		folio_add_file_rmap_pmd(folio, &folio->page, vma);
 		add_mm_counter(mm, mm_counter_file(folio), HPAGE_PMD_NR);
 	}
-	error = insert_pfn_pmd(vma, addr, vmf->pmd,
-			pfn_to_pfn_t(folio_pfn(folio)), vma->vm_page_prot,
-			write, pgtable);
+	error = insert_pfn_pmd(vma, addr, vmf->pmd, folio_pfn(folio),
+			       vma->vm_page_prot, write, pgtable);
 	spin_unlock(ptl);
 	if (error && pgtable)
 		pte_free(mm, pgtable);
@@ -1511,7 +1510,7 @@ static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
 }
 
 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
-		pud_t *pud, pfn_t pfn, bool write)
+		pud_t *pud, unsigned long pfn, bool write)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	pgprot_t prot = vma->vm_page_prot;
@@ -1519,7 +1518,7 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
 
 	if (!pud_none(*pud)) {
 		if (write) {
-			if (WARN_ON_ONCE(pud_pfn(*pud) != pfn_t_to_pfn(pfn)))
+			if (WARN_ON_ONCE(pud_pfn(*pud) != pfn))
 				return;
 			entry = pud_mkyoung(*pud);
 			entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
@@ -1529,7 +1528,7 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
 		return;
 	}
 
-	entry = pud_mkhuge(pfn_t_pud(pfn, prot));
+	entry = pud_mkhuge(pfn_pud(pfn, prot));
 	entry = pud_mkspecial(entry);
 	if (write) {
 		entry = pud_mkyoung(pud_mkdirty(entry));
@@ -1549,7 +1548,8 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
  *
  * Return: vm_fault_t value.
  */
-vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
+vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, unsigned long pfn,
+			      bool write)
 {
 	unsigned long addr = vmf->address & PUD_MASK;
 	struct vm_area_struct *vma = vmf->vma;
@@ -1614,8 +1614,7 @@ vm_fault_t vmf_insert_folio_pud(struct vm_fault *vmf, struct folio *folio,
 		folio_add_file_rmap_pud(folio, &folio->page, vma);
 		add_mm_counter(mm, mm_counter_file(folio), HPAGE_PUD_NR);
 	}
-	insert_pfn_pud(vma, addr, vmf->pud, pfn_to_pfn_t(folio_pfn(folio)),
-		write);
+	insert_pfn_pud(vma, addr, vmf->pud, folio_pfn(folio), write);
 	spin_unlock(ptl);
 
 	return VM_FAULT_NOPAGE;
diff --git a/mm/memory.c b/mm/memory.c
index 6b03771..4eaf444 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -57,7 +57,6 @@
 #include <linux/export.h>
 #include <linux/delayacct.h>
 #include <linux/init.h>
-#include <linux/pfn_t.h>
 #include <linux/writeback.h>
 #include <linux/memcontrol.h>
 #include <linux/mmu_notifier.h>
@@ -2405,7 +2404,7 @@ int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
 EXPORT_SYMBOL(vm_map_pages_zero);
 
 static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
-			pfn_t pfn, pgprot_t prot, bool mkwrite)
+			unsigned long pfn, pgprot_t prot, bool mkwrite)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	pte_t *pte, entry;
@@ -2427,7 +2426,7 @@ static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 			 * allocation and mapping invalidation so just skip the
 			 * update.
 			 */
-			if (pte_pfn(entry) != pfn_t_to_pfn(pfn)) {
+			if (pte_pfn(entry) != pfn) {
 				WARN_ON_ONCE(!is_zero_pfn(pte_pfn(entry)));
 				goto out_unlock;
 			}
@@ -2440,7 +2439,7 @@ static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 	}
 
 	/* Ok, finally just insert the thing.. */
-	entry = pte_mkspecial(pfn_t_pte(pfn, prot));
+	entry = pte_mkspecial(pfn_pte(pfn, prot));
 
 	if (mkwrite) {
 		entry = pte_mkyoung(entry);
@@ -2509,10 +2508,9 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 	if (!pfn_modify_allowed(pfn, pgprot))
 		return VM_FAULT_SIGBUS;
 
-	track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, 0));
+	track_pfn_insert(vma, &pgprot, pfn);
 
-	return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, 0), pgprot,
-			false);
+	return insert_pfn(vma, addr, pfn, pgprot, false);
 }
 EXPORT_SYMBOL(vmf_insert_pfn_prot);
 
@@ -2543,21 +2541,22 @@ vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 }
 EXPORT_SYMBOL(vmf_insert_pfn);
 
-static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn, bool mkwrite)
+static bool vm_mixed_ok(struct vm_area_struct *vma, unsigned long pfn,
+			bool mkwrite)
 {
-	if (unlikely(is_zero_pfn(pfn_t_to_pfn(pfn))) &&
+	if (unlikely(is_zero_pfn(pfn)) &&
 	    (mkwrite || !vm_mixed_zeropage_allowed(vma)))
 		return false;
 	/* these checks mirror the abort conditions in vm_normal_page */
 	if (vma->vm_flags & VM_MIXEDMAP)
 		return true;
-	if (is_zero_pfn(pfn_t_to_pfn(pfn)))
+	if (is_zero_pfn(pfn))
 		return true;
 	return false;
 }
 
 static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
-		unsigned long addr, pfn_t pfn, bool mkwrite)
+		unsigned long addr, unsigned long pfn, bool mkwrite)
 {
 	pgprot_t pgprot = vma->vm_page_prot;
 	int err;
@@ -2570,7 +2569,7 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
 
 	track_pfn_insert(vma, &pgprot, pfn);
 
-	if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
+	if (!pfn_modify_allowed(pfn, pgprot))
 		return VM_FAULT_SIGBUS;
 
 	/*
@@ -2580,7 +2579,7 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
 	 * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
 	 * without pte special, it would there be refcounted as a normal page.
 	 */
-	if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pfn_t_valid(pfn)) {
+	if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pfn_valid(pfn)) {
 		struct page *page;
 
 		/*
@@ -2588,7 +2587,7 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
 		 * regardless of whether the caller specified flags that
 		 * result in pfn_t_has_page() == false.
 		 */
-		page = pfn_to_page(pfn_t_to_pfn(pfn));
+		page = pfn_to_page(pfn);
 		err = insert_page(vma, addr, page, pgprot, mkwrite);
 	} else {
 		return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
@@ -2623,7 +2622,7 @@ vm_fault_t vmf_insert_page_mkwrite(struct vm_fault *vmf, struct page *page,
 EXPORT_SYMBOL_GPL(vmf_insert_page_mkwrite);
 
 vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
-		pfn_t pfn)
+		unsigned long pfn)
 {
 	return __vm_insert_mixed(vma, addr, pfn, false);
 }
@@ -2635,7 +2634,7 @@ EXPORT_SYMBOL(vmf_insert_mixed);
  *  the same entry was actually inserted.
  */
 vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
-		unsigned long addr, pfn_t pfn)
+		unsigned long addr, unsigned long pfn)
 {
 	return __vm_insert_mixed(vma, addr, pfn, true);
 }
diff --git a/mm/memremap.c b/mm/memremap.c
index 2aebc1b..2ea5322 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -5,7 +5,6 @@
 #include <linux/kasan.h>
 #include <linux/memory_hotplug.h>
 #include <linux/memremap.h>
-#include <linux/pfn_t.h>
 #include <linux/swap.h>
 #include <linux/mm.h>
 #include <linux/mmzone.h>
diff --git a/mm/migrate.c b/mm/migrate.c
index 676d9cf..2de1b47 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -35,7 +35,6 @@
 #include <linux/compat.h>
 #include <linux/hugetlb.h>
 #include <linux/gfp.h>
-#include <linux/pfn_t.h>
 #include <linux/page_idle.h>
 #include <linux/page_owner.h>
 #include <linux/sched/mm.h>
diff --git a/tools/testing/nvdimm/pmem-dax.c b/tools/testing/nvdimm/pmem-dax.c
index c1ec099..05e763a 100644
--- a/tools/testing/nvdimm/pmem-dax.c
+++ b/tools/testing/nvdimm/pmem-dax.c
@@ -10,7 +10,7 @@
 
 long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 		long nr_pages, enum dax_access_mode mode, void **kaddr,
-		pfn_t *pfn)
+		unsigned long *pfn)
 {
 	resource_size_t offset = PFN_PHYS(pgoff) + pmem->data_offset;
 
@@ -29,7 +29,7 @@ long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 			*kaddr = pmem->virt_addr + offset;
 		page = vmalloc_to_page(pmem->virt_addr + offset);
 		if (pfn)
-			*pfn = page_to_pfn_t(page);
+			*pfn = page_to_pfn(page);
 		pr_debug_ratelimited("%s: pmem: %p pgoff: %#lx pfn: %#lx\n",
 				__func__, pmem, pgoff, page_to_pfn(page));
 
@@ -39,7 +39,7 @@ long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 	if (kaddr)
 		*kaddr = pmem->virt_addr + offset;
 	if (pfn)
-		*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
+		*pfn = PHYS_PFN(pmem->phys_addr + offset);
 
 	/*
 	 * If badblocks are present, limit known good range to the
diff --git a/tools/testing/nvdimm/test/iomap.c b/tools/testing/nvdimm/test/iomap.c
index ddceb04..f7e7bfe 100644
--- a/tools/testing/nvdimm/test/iomap.c
+++ b/tools/testing/nvdimm/test/iomap.c
@@ -8,7 +8,6 @@
 #include <linux/ioport.h>
 #include <linux/module.h>
 #include <linux/types.h>
-#include <linux/pfn_t.h>
 #include <linux/acpi.h>
 #include <linux/io.h>
 #include <linux/mm.h>
@@ -135,12 +134,6 @@ void *__wrap_devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 }
 EXPORT_SYMBOL_GPL(__wrap_devm_memremap_pages);
 
-pfn_t __wrap_phys_to_pfn_t(phys_addr_t addr, unsigned long flags)
-{
-        return phys_to_pfn_t(addr, flags);
-}
-EXPORT_SYMBOL(__wrap_phys_to_pfn_t);
-
 void *__wrap_memremap(resource_size_t offset, size_t size,
 		unsigned long flags)
 {
diff --git a/tools/testing/nvdimm/test/nfit_test.h b/tools/testing/nvdimm/test/nfit_test.h
index b00583d..b9047fb 100644
--- a/tools/testing/nvdimm/test/nfit_test.h
+++ b/tools/testing/nvdimm/test/nfit_test.h
@@ -212,7 +212,6 @@ void __iomem *__wrap_devm_ioremap(struct device *dev,
 void *__wrap_devm_memremap(struct device *dev, resource_size_t offset,
 		size_t size, unsigned long flags);
 void *__wrap_devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
-pfn_t __wrap_phys_to_pfn_t(phys_addr_t addr, unsigned long flags);
 void *__wrap_memremap(resource_size_t offset, size_t size,
 		unsigned long flags);
 void __wrap_devm_memunmap(struct device *dev, void *addr);
-- 
git-series 0.9.1

[PATCH 12/12] mm/memremap: Remove unused devmap_managed_key

[Alistair Popple]

It's no longer used so remove it.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 mm/memremap.c | 27 ---------------------------
 1 file changed, 27 deletions(-)

diff --git a/mm/memremap.c b/mm/memremap.c
index 2ea5322..5deb181 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -38,30 +38,6 @@ unsigned long memremap_compat_align(void)
 EXPORT_SYMBOL_GPL(memremap_compat_align);
 #endif
 
-#ifdef CONFIG_FS_DAX
-DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
-EXPORT_SYMBOL(devmap_managed_key);
-
-static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
-{
-	if (pgmap->type == MEMORY_DEVICE_FS_DAX)
-		static_branch_dec(&devmap_managed_key);
-}
-
-static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
-{
-	if (pgmap->type == MEMORY_DEVICE_FS_DAX)
-		static_branch_inc(&devmap_managed_key);
-}
-#else
-static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
-{
-}
-static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
-{
-}
-#endif /* CONFIG_FS_DAX */
-
 static void pgmap_array_delete(struct range *range)
 {
 	xa_store_range(&pgmap_array, PHYS_PFN(range->start), PHYS_PFN(range->end),
@@ -150,7 +126,6 @@ void memunmap_pages(struct dev_pagemap *pgmap)
 	percpu_ref_exit(&pgmap->ref);
 
 	WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
-	devmap_managed_enable_put(pgmap);
 }
 EXPORT_SYMBOL_GPL(memunmap_pages);
 
@@ -353,8 +328,6 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
 	if (error)
 		return ERR_PTR(error);
 
-	devmap_managed_enable_get(pgmap);
-
 	/*
 	 * Clear the pgmap nr_range as it will be incremented for each
 	 * successfully processed range. This communicates how many
-- 
git-series 0.9.1

Re: [PATCH 01/12] mm: Remove PFN_MAP, PFN_SG_CHAIN and PFN_SG_LAST

[Jonathan Cameron]

On Thu, 29 May 2025 16:32:02 +1000
Alistair Popple <apopple@nvidia.com> wrote:

> The PFN_MAP flag is no longer used for anything, so remove it. The
> PFN_SG_CHAIN and PFN_SG_LAST flags never appear to have been used so
> also remove them.

Superficial thing but you seem to be be removing PFN_SPECIAL as well and
this description and patche description don't mention that.

> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

On superficial comment inline.

> ---
>  include/linux/pfn_t.h             | 31 +++----------------------------
>  mm/memory.c                       |  2 --
>  tools/testing/nvdimm/test/iomap.c |  4 ----
>  3 files changed, 3 insertions(+), 34 deletions(-)
> 
> diff --git a/include/linux/pfn_t.h b/include/linux/pfn_t.h
> index 2d91482..46afa12 100644
> --- a/include/linux/pfn_t.h
> +++ b/include/linux/pfn_t.h
> @@ -5,26 +5,13 @@



> diff --git a/tools/testing/nvdimm/test/iomap.c b/tools/testing/nvdimm/test/iomap.c
> index e431372..ddceb04 100644
> --- a/tools/testing/nvdimm/test/iomap.c
> +++ b/tools/testing/nvdimm/test/iomap.c
> @@ -137,10 +137,6 @@ EXPORT_SYMBOL_GPL(__wrap_devm_memremap_pages);
>  
>  pfn_t __wrap_phys_to_pfn_t(phys_addr_t addr, unsigned long flags)
>  {
> -	struct nfit_test_resource *nfit_res = get_nfit_res(addr);
> -
> -	if (nfit_res)
> -		flags &= ~PFN_MAP;
>          return phys_to_pfn_t(addr, flags);

Maybe not the time to point it out, but what is going on with indent here?
Looks like some spaces snuck in for that last line.



>  }
>  EXPORT_SYMBOL(__wrap_phys_to_pfn_t);

Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls

[Jonathan Cameron]

On Thu, 29 May 2025 16:32:08 +1000
Alistair Popple <apopple@nvidia.com> wrote:

> DAX was the only thing that created pmd_devmap and pud_devmap entries
> however it no longer does as DAX pages are now refcounted normally and
> pXd_trans_huge() returns true for those. Therefore checking both pXd_devmap
> and pXd_trans_huge() is redundant and the former can be removed without
> changing behaviour as it will always be false.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>

> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 8d9d706..31b4110 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1398,10 +1398,7 @@ static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
>  	}
>  
>  	entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
> -	if (pfn_t_devmap(pfn))

Didn't this go away in patch 5?  I didn't check but this looks like a bisectability issue.

> -		entry = pmd_mkdevmap(entry);
> -	else
> -		entry = pmd_mkspecial(entry);
> +	entry = pmd_mkspecial(entry);
>  	if (write) {
>  		entry = pmd_mkyoung(pmd_mkdirty(entry));
>  		entry = maybe_pmd_mkwrite(entry, vma);

Re: [PATCH 01/12] mm: Remove PFN_MAP, PFN_SG_CHAIN and PFN_SG_LAST

[David Hildenbrand]

On 29.05.25 08:32, Alistair Popple wrote:
> The PFN_MAP flag is no longer used for anything, so remove it. The
> PFN_SG_CHAIN and PFN_SG_LAST flags never appear to have been used so
> also remove them.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---

With SPECIAL mentioned as well

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb

Re: [PATCH 02/12] mm: Convert pXd_devmap checks to vma_is_dax

[David Hildenbrand]

On 29.05.25 08:32, Alistair Popple wrote:
> Currently dax is the only user of pmd and pud mapped ZONE_DEVICE
> pages. Therefore page walkers that want to exclude DAX pages can check
> pmd_devmap or pud_devmap. However soon dax will no longer set PFN_DEV,
> meaning dax pages are mapped as normal pages.
> 
> Ensure page walkers that currently use pXd_devmap to skip DAX pages
> continue to do so by adding explicit checks of the VMA instead.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>   fs/userfaultfd.c | 2 +-
>   mm/hmm.c         | 2 +-
>   mm/userfaultfd.c | 2 +-
>   3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> index 22f4bf9..de671d3 100644
> --- a/fs/userfaultfd.c
> +++ b/fs/userfaultfd.c
> @@ -304,7 +304,7 @@ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx,
>   		goto out;
>   
>   	ret = false;
> -	if (!pmd_present(_pmd) || pmd_devmap(_pmd))
> +	if (!pmd_present(_pmd) || vma_is_dax(vmf->vma))
>   		goto out;
>   
>   	if (pmd_trans_huge(_pmd)) {
> diff --git a/mm/hmm.c b/mm/hmm.c
> index 082f7b7..db12c0a 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -429,7 +429,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
>   		return hmm_vma_walk_hole(start, end, -1, walk);
>   	}
>   
> -	if (pud_leaf(pud) && pud_devmap(pud)) {
> +	if (pud_leaf(pud) && vma_is_dax(walk->vma)) {
>   		unsigned long i, npages, pfn;
>   		unsigned int required_fault;
>   		unsigned long *hmm_pfns;
> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> index e0db855..133f750 100644
> --- a/mm/userfaultfd.c
> +++ b/mm/userfaultfd.c
> @@ -1791,7 +1791,7 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
>   
>   		ptl = pmd_trans_huge_lock(src_pmd, src_vma);
>   		if (ptl) {
> -			if (pmd_devmap(*src_pmd)) {
> +			if (vma_is_dax(src_vma)) {
>   				spin_unlock(ptl);
>   				err = -ENOENT;
>   				break;

I assume we could also just refuse dax folios, right?

If we decide to check VMAs, we should probably check earlier.

But I wonder, what about anonymous non-dax pages in COW mappings? Is it 
possible? Not supported?

If supported, checking the actual folio would be the right thing to do.

-- 
Cheers,

David / dhildenb

Re: [PATCH 03/12] mm/pagewalk: Skip dax pages in pagewalk

[David Hildenbrand]

On 29.05.25 08:32, Alistair Popple wrote:
> Previously dax pages were skipped by the pagewalk code as pud_special() or
> vm_normal_page{_pmd}() would be false for DAX pages. Now that dax pages are
> refcounted normally that is no longer the case, so add explicit checks to
> skip them.

Is this really what we want, though? If these are now just "normal" 
pages, they shall be handled as being normal.

I would assume that we want to check that in the callers instead.

E.g., in get_mergeable_page() we already have a folio_is_zone_device() 
check.

> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>   include/linux/memremap.h | 11 +++++++++++
>   mm/pagewalk.c            | 12 ++++++++++--
>   2 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/memremap.h b/include/linux/memremap.h
> index 4aa1519..54e8b57 100644
> --- a/include/linux/memremap.h
> +++ b/include/linux/memremap.h
> @@ -198,6 +198,17 @@ static inline bool folio_is_fsdax(const struct folio *folio)
>   	return is_fsdax_page(&folio->page);
>   }
>   
> +static inline bool is_devdax_page(const struct page *page)
> +{
> +	return is_zone_device_page(page) &&
> +		page_pgmap(page)->type == MEMORY_DEVICE_GENERIC;
> +}
> +
> +static inline bool folio_is_devdax(const struct folio *folio)
> +{
> +	return is_devdax_page(&folio->page);
> +}

Hm, nobody uses folio_is_devdax() in this patch :)


-- 
Cheers,

David / dhildenb

RE: [PATCH 11/12] mm: Remove callers of pfn_t functionality

[Michael Kelley]

From: Alistair Popple <apopple@nvidia.com> Sent: Wednesday, May 28, 2025 11:32 PM
> 
> All PFN_* pfn_t flags have been removed. Therefore there is no longer
> a need for the pfn_t type and all uses can be replaced with normal
> pfns.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>  arch/x86/mm/pat/memtype.c                |  6 +-
>  drivers/dax/device.c                     | 23 +++----
>  drivers/dax/hmem/hmem.c                  |  1 +-
>  drivers/dax/kmem.c                       |  1 +-
>  drivers/dax/pmem.c                       |  1 +-
>  drivers/dax/super.c                      |  3 +-
>  drivers/gpu/drm/exynos/exynos_drm_gem.c  |  1 +-
>  drivers/gpu/drm/gma500/fbdev.c           |  3 +-
>  drivers/gpu/drm/i915/gem/i915_gem_mman.c |  1 +-
>  drivers/gpu/drm/msm/msm_gem.c            |  1 +-
>  drivers/gpu/drm/omapdrm/omap_gem.c       |  6 +--
>  drivers/gpu/drm/v3d/v3d_bo.c             |  1 +-
>  drivers/hwtracing/intel_th/msu.c         |  3 +-
>  drivers/md/dm-linear.c                   |  2 +-
>  drivers/md/dm-log-writes.c               |  2 +-
>  drivers/md/dm-stripe.c                   |  2 +-
>  drivers/md/dm-target.c                   |  2 +-
>  drivers/md/dm-writecache.c               | 11 +--
>  drivers/md/dm.c                          |  2 +-
>  drivers/nvdimm/pmem.c                    |  8 +--
>  drivers/nvdimm/pmem.h                    |  4 +-
>  drivers/s390/block/dcssblk.c             |  9 +--
>  drivers/vfio/pci/vfio_pci_core.c         |  5 +-
>  fs/cramfs/inode.c                        |  5 +-
>  fs/dax.c                                 | 50 +++++++--------
>  fs/ext4/file.c                           |  2 +-
>  fs/fuse/dax.c                            |  3 +-
>  fs/fuse/virtio_fs.c                      |  5 +-
>  fs/xfs/xfs_file.c                        |  2 +-
>  include/linux/dax.h                      |  9 +--
>  include/linux/device-mapper.h            |  2 +-
>  include/linux/huge_mm.h                  |  6 +-
>  include/linux/mm.h                       |  4 +-
>  include/linux/pfn.h                      |  9 +---
>  include/linux/pfn_t.h                    | 85 +-------------------------
>  include/linux/pgtable.h                  |  4 +-
>  include/trace/events/fs_dax.h            | 12 +---
>  mm/debug_vm_pgtable.c                    |  1 +-
>  mm/huge_memory.c                         | 27 +++-----
>  mm/memory.c                              | 31 ++++-----
>  mm/memremap.c                            |  1 +-
>  mm/migrate.c                             |  1 +-
>  tools/testing/nvdimm/pmem-dax.c          |  6 +-
>  tools/testing/nvdimm/test/iomap.c        |  7 +--
>  tools/testing/nvdimm/test/nfit_test.h    |  1 +-
>  45 files changed, 121 insertions(+), 250 deletions(-)
>  delete mode 100644 include/linux/pfn_t.h
> 

[snip]

> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index c5345ee..12d9665 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3644,9 +3644,9 @@ vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
>  vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
>  			unsigned long pfn, pgprot_t pgprot);
>  vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
> -			pfn_t pfn);
> +			unsigned long pfn);
>  vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
> -		unsigned long addr, pfn_t pfn);
> +		unsigned long addr, unsigned long pfn);
>  int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
> 
>  static inline vm_fault_t vmf_insert_page(struct vm_area_struct *vma,

[snip]

> diff --git a/mm/memory.c b/mm/memory.c
> index 6b03771..4eaf444 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2635,7 +2634,7 @@ EXPORT_SYMBOL(vmf_insert_mixed);
>   *  the same entry was actually inserted.
>   */
>  vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
> -		unsigned long addr, pfn_t pfn)
> +		unsigned long addr, unsigned long pfn)
>  {
>  	return __vm_insert_mixed(vma, addr, pfn, true);
>  }

vmf_insert_mixed_mkwrite() is not used anywhere in the
kernel. The commit message for cd1e0dac3a3e suggests it was
originally used by DAX code, so presumably it could just go away.

On the flip side, I have a patch set in flight (see Patch 3 of [1])
that uses it to do mkwrite on a special PTE, and my usage
requires passing PFN_SPECIAL in order to pass the tests in
vm_mixed_ok(). But this may be dubious usage, and should not
be a blocker to your elimination of pfn_t. I'll either add
vmf_insert_special_mkwrite() or figure out an equivalent. Anyone
with suggestions in that direction would be appreciated as I'm
not an mm expert.

Michael

[1] https://lore.kernel.org/linux-hyperv/20250523161522.409504-1-mhklinux@outlook.com/

Re: [PATCH 01/12] mm: Remove PFN_MAP, PFN_SG_CHAIN and PFN_SG_LAST

[Christoph Hellwig]

On Thu, May 29, 2025 at 04:32:02PM +1000, Alistair Popple wrote:
> The PFN_MAP flag is no longer used for anything, so remove it. The
> PFN_SG_CHAIN and PFN_SG_LAST flags never appear to have been used so
> also remove them.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

FYI, unlike the rest of the series that has some non-trivial work
this feels like a 6.16-rc candidate as it just removes dead code
and we'd better get that in before a new user or even just a conflict
sneaks in.

Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls

[David Hildenbrand]

> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1398,10 +1398,7 @@ static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
>   	}
>   
>   	entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
> -	if (pfn_t_devmap(pfn))
> -		entry = pmd_mkdevmap(entry);
> -	else
> -		entry = pmd_mkspecial(entry);
> +	entry = pmd_mkspecial(entry);
>   	if (write) {


I just stumbled over this, and I think there is something off here in 
the PMD/PUD case.

vmf_insert_folio_pmd() does a folio_get() + folio_add_file_rmap_pmd().

But then, we go ahead and turn this into a special mapping by setting it 
pmd_mkdevmap()/pmd_mkspecial().

Consequently, vm_normal_page_pmd() would ignore them, not following the 
rules documented for vm_normal_page() and behaving differently than 
vmf_insert_page_mkwrite()->insert_page().


folio_add_file_rmap_pmd() should never set these things special/devmap 
in the first place :/

What am I missing?

Note that fs/dax.c calls vmf_insert_folio_pmd() for PMDs and 
vmf_insert_page_mkwrite() for PTEs.

Consequently, PTEs will never be marked special (corner case, shared 
zeropage), but PMDs would always.

Hm?

-- 
Cheers,

David / dhildenb

Re: [PATCH 00/12] mm: Remove pXX_devmap page table bit and pfn_t type

[David Hildenbrand]

On 29.05.25 08:32, Alistair Popple wrote:
> Changes from v2 of the RFC[1]:
> 
>   - My ZONE_DEVICE refcount series has been merged as commit 7851bf649d42 (Patch series
>     "fs/dax: Fix ZONE_DEVICE page reference counts", v9.) which is included in
>     v6.15 so have rebased on top of that.
> 
>   - No major changes required for the rebase other than fixing up a new user of
>     the pfn_t type (intel_th).
> 
>   - As a reminder the main benefit of this series is it frees up a PTE bit
>     (pte_devmap).
> 
>   - This may be a bit late to consider for inclusion in v6.16 unless it can get
>     some more reviews before the merge window closes. I don't think missing v6.16
>     is a huge issue though.
> 
>   - This passed xfstests for a XFS filesystem with DAX enabled on my system and
>     as many of the ndctl tests that pass on my system without it.
> 
> Changes for v2:
> 
>   - This is an update to my previous RFC[2] removing just pfn_t rebased
>     on today's mm-unstable which includes my ZONE_DEVICE refcounting
>     clean-up.
> 
>   - The removal of the devmap PTE bit and associated infrastructure was
>     dropped from that series so I have rolled it into this series.
> 
>   - Logically this series makes sense to me, but the dropping of devmap
>     is wide ranging and touches some areas I'm less familiar with so
>     would definitely appreciate any review comments there.
> 
> [1] - https://lore.kernel.org/linux-mm/cover.95ff0627bc727f2bae44bea4c00ad7a83fbbcfac.1739941374.git-series.apopple@nvidia.com/
> [2] - https://lore.kernel.org/linux-mm/cover.a7cdeffaaa366a10c65e2e7544285059cc5d55a4.1736299058.git-series.apopple@nvidia.com/
> 
> All users of dax now require a ZONE_DEVICE page which is properly
> refcounted. This means there is no longer any need for the PFN_DEV, PFN_MAP
> and PFN_SPECIAL flags. Furthermore the PFN_SG_CHAIN and PFN_SG_LAST flags
> never appear to have been used. It is therefore possible to remove the
> pfn_t type and replace any usage with raw pfns.
> 
> The remaining users of PFN_DEV have simply passed this to
> vmf_insert_mixed() to create pte_devmap() mappings. It is unclear why this
> was the case but presumably to ensure vm_normal_page() does not return
> these pages. These users can be trivially converted to raw pfns and
> creating a pXX_special() mapping to ensure vm_normal_page() still doesn't
> return these pages.
> 
> Now that there are no users of PFN_DEV we can remove the devmap page table
> bit and all associated functions and macros, freeing up a software page
> table bit.
> 

$ git grep FS_DAX_LIMITED
fs/Kconfig:     depends on ZONE_DEVICE || FS_DAX_LIMITED
fs/Kconfig:config FS_DAX_LIMITED
fs/dax.c:       if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
fs/dax.c:       if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
fs/dax.c:       if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
include/linux/pfn_t.h: * PFN_SPECIAL - for CONFIG_FS_DAX_LIMITED builds 
to allow XIP, but not
mm/memremap.c:          if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {

Can we remove that? Especially the interaction with PFN_SPECIAL looks 
concerning.

-- 
Cheers,

David / dhildenb

Re: [PATCH 08/12] mm/khugepaged: Remove redundant pmd_devmap() check

[David Hildenbrand]

On 29.05.25 08:32, Alistair Popple wrote:
> The only users of pmd_devmap were device dax and fs dax. The check for
> pmd_devmap() in check_pmd_state() is therefore redundant as callers
> explicitly check for is_zone_device_page(), so this check can be dropped.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb

Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls

[David Hildenbrand]

On 02.06.25 11:33, David Hildenbrand wrote:
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -1398,10 +1398,7 @@ static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
>>    	}
>>    
>>    	entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
>> -	if (pfn_t_devmap(pfn))
>> -		entry = pmd_mkdevmap(entry);
>> -	else
>> -		entry = pmd_mkspecial(entry);
>> +	entry = pmd_mkspecial(entry);
>>    	if (write) {
> 
> 
> I just stumbled over this, and I think there is something off here in
> the PMD/PUD case.
> 
> vmf_insert_folio_pmd() does a folio_get() + folio_add_file_rmap_pmd().
> 
> But then, we go ahead and turn this into a special mapping by setting it
> pmd_mkdevmap()/pmd_mkspecial().
> 
> Consequently, vm_normal_page_pmd() would ignore them, not following the
> rules documented for vm_normal_page() and behaving differently than
> vmf_insert_page_mkwrite()->insert_page().
> 
> 
> folio_add_file_rmap_pmd() should never set these things special/devmap
> in the first place :/
> 
> What am I missing?
> 
> Note that fs/dax.c calls vmf_insert_folio_pmd() for PMDs and
> vmf_insert_page_mkwrite() for PTEs.
> 
> Consequently, PTEs will never be marked special (corner case, shared
> zeropage), but PMDs would always.
> 
> Hm?

What an ugly piece of crap this pmd handling code is.

Just noting because I stumbled over that myself:

pmd_mkdevmap() does *not* imply pmd_special().

... in contrast to pte_mkdevmap(), which will imply pte_special().


-- 
Cheers,

David / dhildenb

Re: [PATCH 01/12] mm: Remove PFN_MAP, PFN_SG_CHAIN and PFN_SG_LAST

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:02PM +1000, Alistair Popple wrote:
> The PFN_MAP flag is no longer used for anything, so remove it. The
> PFN_SG_CHAIN and PFN_SG_LAST flags never appear to have been used so
> also remove them.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>  include/linux/pfn_t.h             | 31 +++----------------------------
>  mm/memory.c                       |  2 --
>  tools/testing/nvdimm/test/iomap.c |  4 ----
>  3 files changed, 3 insertions(+), 34 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH 02/12] mm: Convert pXd_devmap checks to vma_is_dax

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:03PM +1000, Alistair Popple wrote:
> Currently dax is the only user of pmd and pud mapped ZONE_DEVICE
> pages. Therefore page walkers that want to exclude DAX pages can check
> pmd_devmap or pud_devmap. However soon dax will no longer set PFN_DEV,
> meaning dax pages are mapped as normal pages.
> 
> Ensure page walkers that currently use pXd_devmap to skip DAX pages
> continue to do so by adding explicit checks of the VMA instead.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>  fs/userfaultfd.c | 2 +-
>  mm/hmm.c         | 2 +-
>  mm/userfaultfd.c | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH 03/12] mm/pagewalk: Skip dax pages in pagewalk

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:04PM +1000, Alistair Popple wrote:
> Previously dax pages were skipped by the pagewalk code as pud_special() or
> vm_normal_page{_pmd}() would be false for DAX pages. Now that dax pages are
> refcounted normally that is no longer the case, so add explicit checks to
> skip them.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>  include/linux/memremap.h | 11 +++++++++++
>  mm/pagewalk.c            | 12 ++++++++++--
>  2 files changed, 21 insertions(+), 2 deletions(-)

But why do we want to skip them?

Like hmm uses pagewalk and it would like to see DAX pages?

I guess it makes sense from the perspective of not changing things,
but it seems like a comment should be left behind explaining that this
is just for legacy reasons until someone audits the callers.

Jason

Re: [PATCH 04/12] mm: Convert vmf_insert_mixed() from using pte_devmap to pte_special

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:05PM +1000, Alistair Popple wrote:
> DAX no longer requires device PTEs as it always has a ZONE_DEVICE page
> associated with the PTE that can be reference counted normally. Other users
> of pte_devmap are drivers that set PFN_DEV when calling vmf_insert_mixed()
> which ensures vm_normal_page() returns NULL for these entries.
> 
> There is no reason to distinguish these pte_devmap users so in order to
> free up a PTE bit use pte_special instead for entries created with
> vmf_insert_mixed(). This will ensure vm_normal_page() will continue to
> return NULL for these pages.
> 
> Architectures that don't support pte_special also don't support pte_devmap
> so those will continue to rely on pfn_valid() to determine if the page can
> be mapped.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>  mm/hmm.c    |  3 ---
>  mm/memory.c | 20 ++------------------
>  mm/vmscan.c |  2 +-
>  3 files changed, 3 insertions(+), 22 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH 05/12] mm: Remove remaining uses of PFN_DEV

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:06PM +1000, Alistair Popple wrote:
> PFN_DEV was used by callers of dax_direct_access() to figure out if the
> returned PFN is associated with a page using pfn_t_has_page() or
> not. However all DAX PFNs now require an assoicated ZONE_DEVICE page so can
> assume a page exists.
> 
> Other users of PFN_DEV were setting it before calling
> vmf_insert_mixed(). This is unnecessary as it is no longer checked, instead
> relying on pfn_valid() to determine if there is an associated page or not.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/gpu/drm/gma500/fbdev.c     |  2 +-
>  drivers/gpu/drm/omapdrm/omap_gem.c |  5 ++---
>  drivers/s390/block/dcssblk.c       |  3 +--
>  drivers/vfio/pci/vfio_pci_core.c   |  6 ++----
>  fs/cramfs/inode.c                  |  2 +-
>  include/linux/pfn_t.h              | 25 ++-----------------------
>  mm/memory.c                        |  4 ++--
>  7 files changed, 11 insertions(+), 36 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH 06/12] mm/gup: Remove pXX_devmap usage from get_user_pages()

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:07PM +1000, Alistair Popple wrote:
> GUP uses pXX_devmap() calls to see if it needs to a get a reference on
> the associated pgmap data structure to ensure the pages won't go
> away. However it's a driver responsibility to ensure that if pages are
> mapped (ie. discoverable by GUP) that they are not offlined or removed
> from the memmap so there is no need to hold a reference on the pgmap
> data structure to ensure this.

Yes, the pgmap refcounting never made any sense here.

But I'm not sure this ever got fully fixed up?

To solve races with GUP fast we need a IPI/synchronize_rcu after all
VMAs are zapped and before the pgmap gets destroyed. Granted it is a
very small race in gup fast, it still should have this locking.

> Furthermore mappings with PFN_DEV are no longer created, hence this
> effectively dead code anyway so can be removed.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>  include/linux/huge_mm.h |   3 +-
>  mm/gup.c                | 162 +----------------------------------------
>  mm/huge_memory.c        |  40 +----------
>  3 files changed, 5 insertions(+), 200 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:08PM +1000, Alistair Popple wrote:
> DAX was the only thing that created pmd_devmap and pud_devmap entries
> however it no longer does as DAX pages are now refcounted normally and
> pXd_trans_huge() returns true for those. Therefore checking both pXd_devmap
> and pXd_trans_huge() is redundant and the former can be removed without
> changing behaviour as it will always be false.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>  fs/dax.c                   |  5 ++---
>  include/linux/huge_mm.h    | 10 ++++------
>  include/linux/pgtable.h    |  2 +-
>  mm/hmm.c                   |  4 ++--
>  mm/huge_memory.c           | 30 +++++++++---------------------
>  mm/mapping_dirty_helpers.c |  4 ++--
>  mm/memory.c                | 15 ++++++---------
>  mm/migrate_device.c        |  2 +-
>  mm/mprotect.c              |  2 +-
>  mm/mremap.c                |  5 ++---
>  mm/page_vma_mapped.c       |  5 ++---
>  mm/pagewalk.c              |  8 +++-----
>  mm/pgtable-generic.c       |  7 +++----
>  mm/userfaultfd.c           |  4 ++--
>  mm/vmscan.c                |  3 ---
>  15 files changed, 40 insertions(+), 66 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH 08/12] mm/khugepaged: Remove redundant pmd_devmap() check

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:09PM +1000, Alistair Popple wrote:
> The only users of pmd_devmap were device dax and fs dax. The check for
> pmd_devmap() in check_pmd_state() is therefore redundant as callers
> explicitly check for is_zone_device_page(), so this check can be dropped.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>  mm/khugepaged.c | 2 --
>  1 file changed, 2 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH 09/12] powerpc: Remove checks for devmap pages and PMDs/PUDs

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:10PM +1000, Alistair Popple wrote:
> PFN_DEV no longer exists. This means no devmap PMDs or PUDs will be
> created, so checking for them is redundant. Instead mappings of pages that
> would have previously returned true for pXd_devmap() will return true for
> pXd_trans_huge()
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>  arch/powerpc/mm/book3s64/hash_hugepage.c |  2 +-
>  arch/powerpc/mm/book3s64/hash_pgtable.c  |  3 +--
>  arch/powerpc/mm/book3s64/hugetlbpage.c   |  2 +-
>  arch/powerpc/mm/book3s64/pgtable.c       | 10 ++++------
>  arch/powerpc/mm/book3s64/radix_pgtable.c |  5 ++---
>  arch/powerpc/mm/pgtable.c                |  2 +-
>  6 files changed, 10 insertions(+), 14 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH 10/12] mm: Remove devmap related functions and page table bits

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:11PM +1000, Alistair Popple wrote:
> Now that DAX and all other reference counts to ZONE_DEVICE pages are
> managed normally there is no need for the special devmap PTE/PMD/PUD
> page table bits. So drop all references to these, freeing up a
> software defined page table bit on architectures supporting it.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Acked-by: Will Deacon <will@kernel.org> # arm64
> Suggested-by: Chunyan Zhang <zhang.lyra@gmail.com>
> Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
> ---
>  Documentation/mm/arch_pgtable_helpers.rst     |  6 +--
>  arch/arm64/Kconfig                            |  1 +-
>  arch/arm64/include/asm/pgtable-prot.h         |  1 +-
>  arch/arm64/include/asm/pgtable.h              | 24 +--------
>  arch/loongarch/Kconfig                        |  1 +-
>  arch/loongarch/include/asm/pgtable-bits.h     |  6 +--
>  arch/loongarch/include/asm/pgtable.h          | 19 +------
>  arch/powerpc/Kconfig                          |  1 +-
>  arch/powerpc/include/asm/book3s/64/hash-4k.h  |  6 +--
>  arch/powerpc/include/asm/book3s/64/hash-64k.h |  7 +--
>  arch/powerpc/include/asm/book3s/64/pgtable.h  | 53 +------------------
>  arch/powerpc/include/asm/book3s/64/radix.h    | 14 +-----
>  arch/riscv/Kconfig                            |  1 +-
>  arch/riscv/include/asm/pgtable-64.h           | 20 +-------
>  arch/riscv/include/asm/pgtable-bits.h         |  1 +-
>  arch/riscv/include/asm/pgtable.h              | 17 +------
>  arch/x86/Kconfig                              |  1 +-
>  arch/x86/include/asm/pgtable.h                | 51 +-----------------
>  arch/x86/include/asm/pgtable_types.h          |  5 +--
>  include/linux/mm.h                            |  7 +--
>  include/linux/pgtable.h                       | 19 +------
>  mm/Kconfig                                    |  4 +-
>  mm/debug_vm_pgtable.c                         | 59 +--------------------
>  mm/hmm.c                                      |  3 +-
>  mm/madvise.c                                  |  8 +--
>  25 files changed, 17 insertions(+), 318 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH 11/12] mm: Remove callers of pfn_t functionality

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:12PM +1000, Alistair Popple wrote:
> All PFN_* pfn_t flags have been removed. Therefore there is no longer
> a need for the pfn_t type and all uses can be replaced with normal
> pfns.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Yay!

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH 12/12] mm/memremap: Remove unused devmap_managed_key

[Jason Gunthorpe]

On Thu, May 29, 2025 at 04:32:13PM +1000, Alistair Popple wrote:
> It's no longer used so remove it.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>  mm/memremap.c | 27 ---------------------------
>  1 file changed, 27 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH 01/12] mm: Remove PFN_MAP, PFN_SG_CHAIN and PFN_SG_LAST

[Alistair Popple]

On Thu, May 29, 2025 at 12:46:20PM +0100, Jonathan Cameron wrote:
> On Thu, 29 May 2025 16:32:02 +1000
> Alistair Popple <apopple@nvidia.com> wrote:
> 
> > The PFN_MAP flag is no longer used for anything, so remove it. The
> > PFN_SG_CHAIN and PFN_SG_LAST flags never appear to have been used so
> > also remove them.
> 
> Superficial thing but you seem to be be removing PFN_SPECIAL as well and
> this description and patche description don't mention that.
> 
> > 
> > Signed-off-by: Alistair Popple <apopple@nvidia.com>
> > Reviewed-by: Christoph Hellwig <hch@lst.de>
> 
> On superficial comment inline.
> 
> > ---
> >  include/linux/pfn_t.h             | 31 +++----------------------------
> >  mm/memory.c                       |  2 --
> >  tools/testing/nvdimm/test/iomap.c |  4 ----
> >  3 files changed, 3 insertions(+), 34 deletions(-)
> > 
> > diff --git a/include/linux/pfn_t.h b/include/linux/pfn_t.h
> > index 2d91482..46afa12 100644
> > --- a/include/linux/pfn_t.h
> > +++ b/include/linux/pfn_t.h
> > @@ -5,26 +5,13 @@
> 
> 
> 
> > diff --git a/tools/testing/nvdimm/test/iomap.c b/tools/testing/nvdimm/test/iomap.c
> > index e431372..ddceb04 100644
> > --- a/tools/testing/nvdimm/test/iomap.c
> > +++ b/tools/testing/nvdimm/test/iomap.c
> > @@ -137,10 +137,6 @@ EXPORT_SYMBOL_GPL(__wrap_devm_memremap_pages);
> >  
> >  pfn_t __wrap_phys_to_pfn_t(phys_addr_t addr, unsigned long flags)
> >  {
> > -	struct nfit_test_resource *nfit_res = get_nfit_res(addr);
> > -
> > -	if (nfit_res)
> > -		flags &= ~PFN_MAP;
> >          return phys_to_pfn_t(addr, flags);
> 
> Maybe not the time to point it out, but what is going on with indent here?
> Looks like some spaces snuck in for that last line.

Yeah weird. I don't think that was me. In any case this gets deleted entirely
later in the series so won't bother to fix it here.

> >  }
> >  EXPORT_SYMBOL(__wrap_phys_to_pfn_t);
> 

Re: [PATCH 01/12] mm: Remove PFN_MAP, PFN_SG_CHAIN and PFN_SG_LAST

[Alistair Popple]

On Mon, Jun 02, 2025 at 06:54:27AM +0200, Christoph Hellwig wrote:
> On Thu, May 29, 2025 at 04:32:02PM +1000, Alistair Popple wrote:
> > The PFN_MAP flag is no longer used for anything, so remove it. The
> > PFN_SG_CHAIN and PFN_SG_LAST flags never appear to have been used so
> > also remove them.
> > 
> > Signed-off-by: Alistair Popple <apopple@nvidia.com>
> > Reviewed-by: Christoph Hellwig <hch@lst.de>
> 
> FYI, unlike the rest of the series that has some non-trivial work
> this feels like a 6.16-rc candidate as it just removes dead code
> and we'd better get that in before a new user or even just a conflict
> sneaks in.

Good idea. I have just sent it as a stand-alone patch.

Re: [PATCH 01/12] mm: Remove PFN_MAP, PFN_SG_CHAIN and PFN_SG_LAST

[Dan Williams]

Alistair Popple wrote:
> The PFN_MAP flag is no longer used for anything, so remove it. The
> PFN_SG_CHAIN and PFN_SG_LAST flags never appear to have been used so
> also remove them.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Looks good and I see PFN_DEV goes later in the series:

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

Re: [PATCH 02/12] mm: Convert pXd_devmap checks to vma_is_dax

[Dan Williams]

Alistair Popple wrote:
> Currently dax is the only user of pmd and pud mapped ZONE_DEVICE
> pages. Therefore page walkers that want to exclude DAX pages can check
> pmd_devmap or pud_devmap. However soon dax will no longer set PFN_DEV,
> meaning dax pages are mapped as normal pages.
> 
> Ensure page walkers that currently use pXd_devmap to skip DAX pages
> continue to do so by adding explicit checks of the VMA instead.

tl;dr:

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

So I went through all the p[mu]d_devmap() checks and indeed this is the
set I also come up with that are implicitly checking for "dax" instead
of checking for "is this a larger than base pte size mapping".

While I am a little uncomfortable with the generality of calling the
policy "dax" in these locations I think it is ok for now. I.e. the
fundamental detail in these paths is "huge pte, but not typical
page-allocator THP page"

Also I would have felt better if some of the leftover places that are
doing "dax" checks but not updated were noted in the changelog just for
review purposes. Like:

"Note paths like follow_huge_pud and follow_pmd_mask also have 'dax'
checks, but those paths are for maintaining dev_pagemap refcounts which
no longer (since v6.15) need to be managed for dax pages. A later patch
cleans those up."

Re: [PATCH 00/12] mm: Remove pXX_devmap page table bit and pfn_t type

[Dan Williams]

Alistair Popple wrote:
[..]
> Alistair Popple (12):
>   mm: Remove PFN_MAP, PFN_SG_CHAIN and PFN_SG_LAST
>   mm: Convert pXd_devmap checks to vma_is_dax
>   mm/pagewalk: Skip dax pages in pagewalk
>   mm: Convert vmf_insert_mixed() from using pte_devmap to pte_special
>   mm: Remove remaining uses of PFN_DEV
>   mm/gup: Remove pXX_devmap usage from get_user_pages()
>   mm: Remove redundant pXd_devmap calls
>   mm/khugepaged: Remove redundant pmd_devmap() check
>   powerpc: Remove checks for devmap pages and PMDs/PUDs
>   mm: Remove devmap related functions and page table bits
>   mm: Remove callers of pfn_t functionality
>   mm/memremap: Remove unused devmap_managed_key

I am still reviewing the individual patches, but it is passing my tests
so you can add for the series:

Tested-by: Dan Williams <dan.j.williams@intel.com>

Re: [PATCH 03/12] mm/pagewalk: Skip dax pages in pagewalk

[Dan Williams]

Alistair Popple wrote:
> Previously dax pages were skipped by the pagewalk code as pud_special() or
> vm_normal_page{_pmd}() would be false for DAX pages. Now that dax pages are
> refcounted normally that is no longer the case, so add explicit checks to
> skip them.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>  include/linux/memremap.h | 11 +++++++++++
>  mm/pagewalk.c            | 12 ++++++++++--
>  2 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/memremap.h b/include/linux/memremap.h
> index 4aa1519..54e8b57 100644
> --- a/include/linux/memremap.h
> +++ b/include/linux/memremap.h
> @@ -198,6 +198,17 @@ static inline bool folio_is_fsdax(const struct folio *folio)
>  	return is_fsdax_page(&folio->page);
>  }
>  
> +static inline bool is_devdax_page(const struct page *page)
> +{
> +	return is_zone_device_page(page) &&
> +		page_pgmap(page)->type == MEMORY_DEVICE_GENERIC;
> +}
> +
> +static inline bool folio_is_devdax(const struct folio *folio)
> +{
> +	return is_devdax_page(&folio->page);
> +}
> +
>  #ifdef CONFIG_ZONE_DEVICE
>  void zone_device_page_init(struct page *page);
>  void *memremap_pages(struct dev_pagemap *pgmap, int nid);
> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
> index e478777..0dfb9c2 100644
> --- a/mm/pagewalk.c
> +++ b/mm/pagewalk.c
> @@ -884,6 +884,12 @@ struct folio *folio_walk_start(struct folio_walk *fw,
>  		 * support PUD mappings in VM_PFNMAP|VM_MIXEDMAP VMAs.
>  		 */
>  		page = pud_page(pud);
> +
> +		if (is_devdax_page(page)) {
> +			spin_unlock(ptl);
> +			goto not_found;
> +		}
> +
>  		goto found;
>  	}
>  
> @@ -911,7 +917,8 @@ struct folio *folio_walk_start(struct folio_walk *fw,
>  			goto pte_table;
>  		} else if (pmd_present(pmd)) {
>  			page = vm_normal_page_pmd(vma, addr, pmd);
> -			if (page) {
> +			if (page && !is_devdax_page(page) &&
> +			    !is_fsdax_page(page)) {

It just looks awkward to say "yup, normal page, but not *that*
'normal'".

What about something like the below? Either way you can add:

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 12d96659e8b4..4e549669166b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2471,6 +2471,27 @@ struct folio *vm_normal_folio_pmd(struct vm_area_struct *vma,
 struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
 				pmd_t pmd);
 
+/* return normal pages backed by the page allocator */
+static inline struct page *vm_normal_gfp_pmd(struct vm_area_struct *vma,
+					     unsigned long addr, pmd_t pmd)
+{
+	struct page *page = vm_normal_page_pmd(vma, addr, pmd);
+
+	if (!is_devdax_page(page) && !is_fsdax_page(page))
+		return page;
+	return NULL;
+}
+
+static inline struct page *vm_normal_gfp_pte(struct vm_area_struct *vma,
+					     unsigned long addr, pte_t pte)
+{
+	struct page *page = vm_normal_page(vma, addr, pte);
+
+	if (!is_devdax_page(page) && !is_fsdax_page(page))
+		return page;
+	return NULL;
+}
+
 void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
 		  unsigned long size);
 void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index cca170fe5be5..54bfece05323 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -914,9 +914,8 @@ struct folio *folio_walk_start(struct folio_walk *fw,
 			spin_unlock(ptl);
 			goto pte_table;
 		} else if (pmd_present(pmd)) {
-			page = vm_normal_page_pmd(vma, addr, pmd);
-			if (page && !is_devdax_page(page) &&
-			    !is_fsdax_page(page)) {
+			page = vm_normal_gfp_pmd(vma, addr, pmd);
+			if (page) {
 				goto found;
 			} else if ((flags & FW_ZEROPAGE) &&
 				    is_huge_zero_pmd(pmd)) {
@@ -949,9 +948,8 @@ struct folio *folio_walk_start(struct folio_walk *fw,
 	fw->pte = pte;
 
 	if (pte_present(pte)) {
-		page = vm_normal_page(vma, addr, pte);
-		if (page && !is_devdax_page(page) &&
-		    !is_fsdax_page(page))
+		page = vm_normal_gfp_pte(vma, addr, pte);
+		if (page)
 			goto found;
 		if ((flags & FW_ZEROPAGE) &&
 		    is_zero_pfn(pte_pfn(pte))) {

Re: [PATCH 04/12] mm: Convert vmf_insert_mixed() from using pte_devmap to pte_special

[Dan Williams]

Alistair Popple wrote:
> DAX no longer requires device PTEs as it always has a ZONE_DEVICE page
> associated with the PTE that can be reference counted normally. Other users
> of pte_devmap are drivers that set PFN_DEV when calling vmf_insert_mixed()
> which ensures vm_normal_page() returns NULL for these entries.
> 
> There is no reason to distinguish these pte_devmap users so in order to
> free up a PTE bit use pte_special instead for entries created with
> vmf_insert_mixed(). This will ensure vm_normal_page() will continue to
> return NULL for these pages.
> 
> Architectures that don't support pte_special also don't support pte_devmap
> so those will continue to rely on pfn_valid() to determine if the page can
> be mapped.

Looks good,

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

Re: [PATCH 05/12] mm: Remove remaining uses of PFN_DEV

[Dan Williams]

Alistair Popple wrote:
> PFN_DEV was used by callers of dax_direct_access() to figure out if the
> returned PFN is associated with a page using pfn_t_has_page() or
> not. However all DAX PFNs now require an assoicated ZONE_DEVICE page so can
> assume a page exists.
> 
> Other users of PFN_DEV were setting it before calling
> vmf_insert_mixed(). This is unnecessary as it is no longer checked, instead
> relying on pfn_valid() to determine if there is an associated page or not.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Looks good,

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

Re: [PATCH 06/12] mm/gup: Remove pXX_devmap usage from get_user_pages()

[Dan Williams]

Alistair Popple wrote:
> GUP uses pXX_devmap() calls to see if it needs to a get a reference on
> the associated pgmap data structure to ensure the pages won't go
> away. However it's a driver responsibility to ensure that if pages are
> mapped (ie. discoverable by GUP) that they are not offlined or removed
> from the memmap so there is no need to hold a reference on the pgmap
> data structure to ensure this.
> 
> Furthermore mappings with PFN_DEV are no longer created, hence this
> effectively dead code anyway so can be removed.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>  include/linux/huge_mm.h |   3 +-
>  mm/gup.c                | 162 +----------------------------------------
>  mm/huge_memory.c        |  40 +----------
>  3 files changed, 5 insertions(+), 200 deletions(-)

Hooray! Goodbye dev_pagemap mess in gup.c.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls

[Dan Williams]

Alistair Popple wrote:
> DAX was the only thing that created pmd_devmap and pud_devmap entries
> however it no longer does as DAX pages are now refcounted normally and
> pXd_trans_huge() returns true for those. Therefore checking both pXd_devmap
> and pXd_trans_huge() is redundant and the former can be removed without
> changing behaviour as it will always be false.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
[..]
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 8d9d706..31b4110 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1398,10 +1398,7 @@ static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
>  	}
>  
>  	entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
> -	if (pfn_t_devmap(pfn))
> -		entry = pmd_mkdevmap(entry);
> -	else
> -		entry = pmd_mkspecial(entry);
> +	entry = pmd_mkspecial(entry);
>  	if (write) {
>  		entry = pmd_mkyoung(pmd_mkdirty(entry));
>  		entry = maybe_pmd_mkwrite(entry, vma);
> @@ -1535,10 +1530,7 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
>  	}
>  
>  	entry = pud_mkhuge(pfn_t_pud(pfn, prot));
> -	if (pfn_t_devmap(pfn))
> -		entry = pud_mkdevmap(entry);
> -	else
> -		entry = pud_mkspecial(entry);
> +	entry = pud_mkspecial(entry);

Wait, why are my gup tests passing?

If all dax pages are special, then vm_normal_page() should never find
them and gup should fail.

...oh, but vm_normal_page_p[mu]d() is not used in the gup path, and
'special' is not set in the pte path.

Yuck, that feels subtle.

I think for any p[mu]d where p[mu]d_page() is ok to use should never set
'special', right?

Re: [PATCH 03/12] mm/pagewalk: Skip dax pages in pagewalk

[Christoph Hellwig]

On Wed, Jun 04, 2025 at 06:59:09PM -0700, Dan Williams wrote:
> +/* return normal pages backed by the page allocator */
> +static inline struct page *vm_normal_gfp_pmd(struct vm_area_struct *vma,
> +					     unsigned long addr, pmd_t pmd)
> +{
> +	struct page *page = vm_normal_page_pmd(vma, addr, pmd);
> +
> +	if (!is_devdax_page(page) && !is_fsdax_page(page))
> +		return page;
> +	return NULL;

If you go for this make it more straight forward by having the
normal path in the main flow:

	if (is_devdax_page(page) || is_fsdax_page(page))
		return NULL;
	return page;

> +static inline struct page *vm_normal_gfp_pte(struct vm_area_struct *vma,
> +					     unsigned long addr, pte_t pte)
> +{
> +	struct page *page = vm_normal_page(vma, addr, pte);
> +
> +	if (!is_devdax_page(page) && !is_fsdax_page(page))
> +		return page;
> +	return NULL;

Same here.

Re: [PATCH 03/12] mm/pagewalk: Skip dax pages in pagewalk

[David Hildenbrand]

On 05.06.25 09:46, Christoph Hellwig wrote:
> On Wed, Jun 04, 2025 at 06:59:09PM -0700, Dan Williams wrote:
>> +/* return normal pages backed by the page allocator */
>> +static inline struct page *vm_normal_gfp_pmd(struct vm_area_struct *vma,
>> +					     unsigned long addr, pmd_t pmd)
>> +{
>> +	struct page *page = vm_normal_page_pmd(vma, addr, pmd);
>> +
>> +	if (!is_devdax_page(page) && !is_fsdax_page(page))
>> +		return page;
>> +	return NULL;
> 
> If you go for this make it more straight forward by having the
> normal path in the main flow:
> 
> 	if (is_devdax_page(page) || is_fsdax_page(page))
> 		return NULL;
> 	return page;

+1

But I'd defer introducing that for now if avoidable. I find the naming 
rather ... suboptimal :)

-- 
Cheers,

David / dhildenb

Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls

[Jason Gunthorpe]

On Wed, Jun 04, 2025 at 07:35:24PM -0700, Dan Williams wrote:

> If all dax pages are special, then vm_normal_page() should never find
> them and gup should fail.
> 
> ...oh, but vm_normal_page_p[mu]d() is not used in the gup path, and
> 'special' is not set in the pte path.

That seems really suboptimal?? Why would pmd and pte be different?

> I think for any p[mu]d where p[mu]d_page() is ok to use should never set
> 'special', right?

There should be dedicated functions for installing pages and PFNs,
only the PFN one would set the special bit.

And certainly your tests *should* be failing as special entries should
never ever be converted to struct page.

Jason

Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls

[David Hildenbrand]

On 05.06.25 14:09, Jason Gunthorpe wrote:
> On Wed, Jun 04, 2025 at 07:35:24PM -0700, Dan Williams wrote:
> 
>> If all dax pages are special, then vm_normal_page() should never find
>> them and gup should fail.
>>
>> ...oh, but vm_normal_page_p[mu]d() is not used in the gup path, and
>> 'special' is not set in the pte path.
> 
> That seems really suboptimal?? Why would pmd and pte be different?
> 
>> I think for any p[mu]d where p[mu]d_page() is ok to use should never set
>> 'special', right?
> 
> There should be dedicated functions for installing pages and PFNs,
> only the PFN one would set the special bit.
> 
> And certainly your tests *should* be failing as special entries should
> never ever be converted to struct page.

Worth reviewing [1] where I clean that up and describe the current 
impact. ;)

What's even worse about this pte_devmap()/pmd_devmap()/... shit (sorry! 
but it's absolute shit) is that some pte_mkdev() set the pte special, 
while others ... don't.

E.g., loongarch

static inline pte_t pte_mkdevmap(pte_t pte)	{ pte_val(pte) |= 
_PAGE_DEVMAP; return pte; }

I don't even know how it can (could) survive vm_normal_page().


Of course, a wild (and different) mixture on pmd_mkdevmap() as well.

So happy to see that go away.

[1] https://lkml.kernel.org/r/20250603211634.2925015-1-david@redhat.com

-- 
Cheers,

David / dhildenb

Re: [PATCH 03/12] mm/pagewalk: Skip dax pages in pagewalk

[Dan Williams]

David Hildenbrand wrote:
> On 05.06.25 09:46, Christoph Hellwig wrote:
> > On Wed, Jun 04, 2025 at 06:59:09PM -0700, Dan Williams wrote:
> >> +/* return normal pages backed by the page allocator */
> >> +static inline struct page *vm_normal_gfp_pmd(struct vm_area_struct *vma,
> >> +					     unsigned long addr, pmd_t pmd)
> >> +{
> >> +	struct page *page = vm_normal_page_pmd(vma, addr, pmd);
> >> +
> >> +	if (!is_devdax_page(page) && !is_fsdax_page(page))
> >> +		return page;
> >> +	return NULL;
> > 
> > If you go for this make it more straight forward by having the
> > normal path in the main flow:
> > 
> > 	if (is_devdax_page(page) || is_fsdax_page(page))
> > 		return NULL;
> > 	return page;
> 
> +1
> 
> But I'd defer introducing that for now if avoidable. I find the naming 
> rather ... suboptimal :)

Agree, that was a "for lack of a better term" suggestion, but the
suggestion is indeed lacking.

Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls

[Dan Williams]

Jason Gunthorpe wrote:
> On Wed, Jun 04, 2025 at 07:35:24PM -0700, Dan Williams wrote:
> 
> > If all dax pages are special, then vm_normal_page() should never find
> > them and gup should fail.
> > 
> > ...oh, but vm_normal_page_p[mu]d() is not used in the gup path, and
> > 'special' is not set in the pte path.
> 
> That seems really suboptimal?? Why would pmd and pte be different?
> 
> > I think for any p[mu]d where p[mu]d_page() is ok to use should never set
> > 'special', right?
> 
> There should be dedicated functions for installing pages and PFNs,
> only the PFN one would set the special bit.
> 
> And certainly your tests *should* be failing as special entries should
> never ever be converted to struct page.

That's the point, the pmd and pud special bit is not considered for gup.
So fixing that requires making it not break dax, but looks like David
has a cleanup for that.

Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls

[Dan Williams]

David Hildenbrand wrote:
> On 05.06.25 14:09, Jason Gunthorpe wrote:
> > On Wed, Jun 04, 2025 at 07:35:24PM -0700, Dan Williams wrote:
> > 
> >> If all dax pages are special, then vm_normal_page() should never find
> >> them and gup should fail.
> >>
> >> ...oh, but vm_normal_page_p[mu]d() is not used in the gup path, and
> >> 'special' is not set in the pte path.
> > 
> > That seems really suboptimal?? Why would pmd and pte be different?
> > 
> >> I think for any p[mu]d where p[mu]d_page() is ok to use should never set
> >> 'special', right?
> > 
> > There should be dedicated functions for installing pages and PFNs,
> > only the PFN one would set the special bit.
> > 
> > And certainly your tests *should* be failing as special entries should
> > never ever be converted to struct page.
> 
> Worth reviewing [1] where I clean that up and describe the current 
> impact. ;)

Will do.

> What's even worse about this pte_devmap()/pmd_devmap()/... shit (sorry! 
> but it's absolute shit) is that some pte_mkdev() set the pte special, 
> while others ... don't.

As the person who started the turd rolling into this pile that Alistair
is heroically cleaning up, I approve this characterization.

> E.g., loongarch
> 
> static inline pte_t pte_mkdevmap(pte_t pte)	{ pte_val(pte) |= 
> _PAGE_DEVMAP; return pte; }
> 
> I don't even know how it can (could) survive vm_normal_page().

Presently "can" because dax switched away from vmf_insert_mixed() to
vmf_insert_page(), "could" in the past was the devmap hack to avoid
treating VM_MIXEDMAP as !vm_normal_page().

Re: [PATCH 07/12] mm: Remove redundant pXd_devmap calls

[David Hildenbrand]

On 05.06.25 18:30, Dan Williams wrote:
> David Hildenbrand wrote:
>> On 05.06.25 14:09, Jason Gunthorpe wrote:
>>> On Wed, Jun 04, 2025 at 07:35:24PM -0700, Dan Williams wrote:
>>>
>>>> If all dax pages are special, then vm_normal_page() should never find
>>>> them and gup should fail.
>>>>
>>>> ...oh, but vm_normal_page_p[mu]d() is not used in the gup path, and
>>>> 'special' is not set in the pte path.
>>>
>>> That seems really suboptimal?? Why would pmd and pte be different?
>>>
>>>> I think for any p[mu]d where p[mu]d_page() is ok to use should never set
>>>> 'special', right?
>>>
>>> There should be dedicated functions for installing pages and PFNs,
>>> only the PFN one would set the special bit.
>>>
>>> And certainly your tests *should* be failing as special entries should
>>> never ever be converted to struct page.
>>
>> Worth reviewing [1] where I clean that up and describe the current
>> impact. ;)
> 
> Will do.
> 
>> What's even worse about this pte_devmap()/pmd_devmap()/... shit (sorry!
>> but it's absolute shit) is that some pte_mkdev() set the pte special,
>> while others ... don't.
> 
> As the person who started the turd rolling into this pile that Alistair
> is heroically cleaning up, I approve this characterization.
> 
>> E.g., loongarch
>>
>> static inline pte_t pte_mkdevmap(pte_t pte)	{ pte_val(pte) |=
>> _PAGE_DEVMAP; return pte; }
>>
>> I don't even know how it can (could) survive vm_normal_page().
> 
> Presently "can" because dax switched away from vmf_insert_mixed() to
> vmf_insert_page(), "could" in the past was the devmap hack to avoid
> treating VM_MIXEDMAP as !vm_normal_page().

The thing is, in vm_normal_page() if we have CONFIG_ARCH_HAS_PTE_SPECIAL 
-- which loongarch sets -- if we don't see pte_special(), we will assume 
that it is refcounted.

	if (likely(!pte_special(pte))
		goto check_pfn;

So if pte_mkdevmap() does not set pte_special(), then ... 
vm_normal_page() would detect it as normal, although it isn't normal?

But maybe I am missing something important.

-- 
Cheers,

David / dhildenb

Re: [PATCH 02/12] mm: Convert pXd_devmap checks to vma_is_dax

[Alistair Popple]

On Fri, May 30, 2025 at 11:37:21AM +0200, David Hildenbrand wrote:
> On 29.05.25 08:32, Alistair Popple wrote:
> > Currently dax is the only user of pmd and pud mapped ZONE_DEVICE
> > pages. Therefore page walkers that want to exclude DAX pages can check
> > pmd_devmap or pud_devmap. However soon dax will no longer set PFN_DEV,
> > meaning dax pages are mapped as normal pages.
> > 
> > Ensure page walkers that currently use pXd_devmap to skip DAX pages
> > continue to do so by adding explicit checks of the VMA instead.
> > 
> > Signed-off-by: Alistair Popple <apopple@nvidia.com>
> > ---
> >   fs/userfaultfd.c | 2 +-
> >   mm/hmm.c         | 2 +-
> >   mm/userfaultfd.c | 2 +-
> >   3 files changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> > index 22f4bf9..de671d3 100644
> > --- a/fs/userfaultfd.c
> > +++ b/fs/userfaultfd.c
> > @@ -304,7 +304,7 @@ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx,
> >   		goto out;
> >   	ret = false;
> > -	if (!pmd_present(_pmd) || pmd_devmap(_pmd))
> > +	if (!pmd_present(_pmd) || vma_is_dax(vmf->vma))
> >   		goto out;
> >   	if (pmd_trans_huge(_pmd)) {
> > diff --git a/mm/hmm.c b/mm/hmm.c
> > index 082f7b7..db12c0a 100644
> > --- a/mm/hmm.c
> > +++ b/mm/hmm.c
> > @@ -429,7 +429,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
> >   		return hmm_vma_walk_hole(start, end, -1, walk);
> >   	}
> > -	if (pud_leaf(pud) && pud_devmap(pud)) {
> > +	if (pud_leaf(pud) && vma_is_dax(walk->vma)) {
> >   		unsigned long i, npages, pfn;
> >   		unsigned int required_fault;
> >   		unsigned long *hmm_pfns;
> > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> > index e0db855..133f750 100644
> > --- a/mm/userfaultfd.c
> > +++ b/mm/userfaultfd.c
> > @@ -1791,7 +1791,7 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
> >   		ptl = pmd_trans_huge_lock(src_pmd, src_vma);
> >   		if (ptl) {
> > -			if (pmd_devmap(*src_pmd)) {
> > +			if (vma_is_dax(src_vma)) {
> >   				spin_unlock(ptl);
> >   				err = -ENOENT;
> >   				break;
> 
> I assume we could also just refuse dax folios, right?

Yep.

> If we decide to check VMAs, we should probably check earlier.

Ok, that makes sense.
 
> But I wonder, what about anonymous non-dax pages in COW mappings? Is it
> possible? Not supported?

You mean other non-dax ZONE_DEVICE pages? Currently not possible, because
non-dax ZONE_DEVICE pages can't be pmd mapped (although it is a future
enhancement I'd like to make).

> If supported, checking the actual folio would be the right thing to do.
> 
> -- 
> Cheers,
> 
> David / dhildenb
> 

Re: [PATCH 03/12] mm/pagewalk: Skip dax pages in pagewalk

[Alistair Popple]

On Thu, Jun 05, 2025 at 09:21:28AM -0700, Dan Williams wrote:
> David Hildenbrand wrote:
> > On 05.06.25 09:46, Christoph Hellwig wrote:
> > > On Wed, Jun 04, 2025 at 06:59:09PM -0700, Dan Williams wrote:
> > >> +/* return normal pages backed by the page allocator */
> > >> +static inline struct page *vm_normal_gfp_pmd(struct vm_area_struct *vma,
> > >> +					     unsigned long addr, pmd_t pmd)
> > >> +{
> > >> +	struct page *page = vm_normal_page_pmd(vma, addr, pmd);
> > >> +
> > >> +	if (!is_devdax_page(page) && !is_fsdax_page(page))
> > >> +		return page;
> > >> +	return NULL;
> > > 
> > > If you go for this make it more straight forward by having the
> > > normal path in the main flow:
> > > 
> > > 	if (is_devdax_page(page) || is_fsdax_page(page))
> > > 		return NULL;
> > > 	return page;
> > 
> > +1
> > 
> > But I'd defer introducing that for now if avoidable. I find the naming 
> > rather ... suboptimal :)
> 
> Agree, that was a "for lack of a better term" suggestion, but the
> suggestion is indeed lacking.

I don't like the naming either ... maybe that is motivation enough for me to
audit the callers and have them explicitly filter the pages they don't want.

Re: [PATCH 03/12] mm/pagewalk: Skip dax pages in pagewalk

[Alistair Popple]

On Thu, Jun 12, 2025 at 05:02:13PM +1000, Alistair Popple wrote:
> On Thu, Jun 05, 2025 at 09:21:28AM -0700, Dan Williams wrote:
> > David Hildenbrand wrote:
> > > On 05.06.25 09:46, Christoph Hellwig wrote:
> > > > On Wed, Jun 04, 2025 at 06:59:09PM -0700, Dan Williams wrote:
> > > >> +/* return normal pages backed by the page allocator */
> > > >> +static inline struct page *vm_normal_gfp_pmd(struct vm_area_struct *vma,
> > > >> +					     unsigned long addr, pmd_t pmd)
> > > >> +{
> > > >> +	struct page *page = vm_normal_page_pmd(vma, addr, pmd);
> > > >> +
> > > >> +	if (!is_devdax_page(page) && !is_fsdax_page(page))
> > > >> +		return page;
> > > >> +	return NULL;
> > > > 
> > > > If you go for this make it more straight forward by having the
> > > > normal path in the main flow:
> > > > 
> > > > 	if (is_devdax_page(page) || is_fsdax_page(page))
> > > > 		return NULL;
> > > > 	return page;
> > > 
> > > +1
> > > 
> > > But I'd defer introducing that for now if avoidable. I find the naming 
> > > rather ... suboptimal :)
> > 
> > Agree, that was a "for lack of a better term" suggestion, but the
> > suggestion is indeed lacking.
> 
> I don't like the naming either ... maybe that is motivation enough for me to
> audit the callers and have them explicitly filter the pages they don't want.

Which actually most of them already do. The only ones I'm unsure about are both
in s390 so I'll be conservative and add checks for folio_is_zone_device() there.

Re: [PATCH 03/12] mm/pagewalk: Skip dax pages in pagewalk

[Lorenzo Stoakes]

On Thu, May 29, 2025 at 04:32:04PM +1000, Alistair Popple wrote:
> Previously dax pages were skipped by the pagewalk code as pud_special() or
> vm_normal_page{_pmd}() would be false for DAX pages. Now that dax pages are
> refcounted normally that is no longer the case, so add explicit checks to
> skip them.
>
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>  include/linux/memremap.h | 11 +++++++++++
>  mm/pagewalk.c            | 12 ++++++++++--
>  2 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/memremap.h b/include/linux/memremap.h
> index 4aa1519..54e8b57 100644
> --- a/include/linux/memremap.h
> +++ b/include/linux/memremap.h
> @@ -198,6 +198,17 @@ static inline bool folio_is_fsdax(const struct folio *folio)
>  	return is_fsdax_page(&folio->page);
>  }
>
> +static inline bool is_devdax_page(const struct page *page)
> +{
> +	return is_zone_device_page(page) &&
> +		page_pgmap(page)->type == MEMORY_DEVICE_GENERIC;
> +}
> +
> +static inline bool folio_is_devdax(const struct folio *folio)
> +{
> +	return is_devdax_page(&folio->page);
> +}
> +
>  #ifdef CONFIG_ZONE_DEVICE
>  void zone_device_page_init(struct page *page);
>  void *memremap_pages(struct dev_pagemap *pgmap, int nid);
> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
> index e478777..0dfb9c2 100644
> --- a/mm/pagewalk.c
> +++ b/mm/pagewalk.c
> @@ -884,6 +884,12 @@ struct folio *folio_walk_start(struct folio_walk *fw,
>  		 * support PUD mappings in VM_PFNMAP|VM_MIXEDMAP VMAs.
>  		 */
>  		page = pud_page(pud);
> +
> +		if (is_devdax_page(page)) {

Is it only devdax that can exist at PUD leaf level, not fsdax?

> +			spin_unlock(ptl);
> +			goto not_found;
> +		}
> +
>  		goto found;
>  	}
>
> @@ -911,7 +917,8 @@ struct folio *folio_walk_start(struct folio_walk *fw,
>  			goto pte_table;
>  		} else if (pmd_present(pmd)) {
>  			page = vm_normal_page_pmd(vma, addr, pmd);
> -			if (page) {
> +			if (page && !is_devdax_page(page) &&
> +			    !is_fsdax_page(page)) {
>  				goto found;
>  			} else if ((flags & FW_ZEROPAGE) &&
>  				    is_huge_zero_pmd(pmd)) {
> @@ -945,7 +952,8 @@ struct folio *folio_walk_start(struct folio_walk *fw,
>
>  	if (pte_present(pte)) {
>  		page = vm_normal_page(vma, addr, pte);
> -		if (page)
> +		if (page && !is_devdax_page(page) &&
> +		    !is_fsdax_page(page))
>  			goto found;
>  		if ((flags & FW_ZEROPAGE) &&
>  		    is_zero_pfn(pte_pfn(pte))) {

I'm probably echoing others here (and I definitely particularly like Dan's
suggestion of a helper function here, and Jason's suggestion of explanatory
comments), but would also be nice to not have to do this separately at each page
table level and instead have something that you can say 'get me normal non-dax
page at page table level <parameter>'.

> --
> git-series 0.9.1

Re: [PATCH 03/12] mm/pagewalk: Skip dax pages in pagewalk

[Alistair Popple]

On Thu, Jun 12, 2025 at 03:15:31PM +0100, Lorenzo Stoakes wrote:
> On Thu, May 29, 2025 at 04:32:04PM +1000, Alistair Popple wrote:
> > Previously dax pages were skipped by the pagewalk code as pud_special() or
> > vm_normal_page{_pmd}() would be false for DAX pages. Now that dax pages are
> > refcounted normally that is no longer the case, so add explicit checks to
> > skip them.
> >
> > Signed-off-by: Alistair Popple <apopple@nvidia.com>
> > ---
> >  include/linux/memremap.h | 11 +++++++++++
> >  mm/pagewalk.c            | 12 ++++++++++--
> >  2 files changed, 21 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/memremap.h b/include/linux/memremap.h
> > index 4aa1519..54e8b57 100644
> > --- a/include/linux/memremap.h
> > +++ b/include/linux/memremap.h
> > @@ -198,6 +198,17 @@ static inline bool folio_is_fsdax(const struct folio *folio)
> >  	return is_fsdax_page(&folio->page);
> >  }
> >
> > +static inline bool is_devdax_page(const struct page *page)
> > +{
> > +	return is_zone_device_page(page) &&
> > +		page_pgmap(page)->type == MEMORY_DEVICE_GENERIC;
> > +}
> > +
> > +static inline bool folio_is_devdax(const struct folio *folio)
> > +{
> > +	return is_devdax_page(&folio->page);
> > +}
> > +
> >  #ifdef CONFIG_ZONE_DEVICE
> >  void zone_device_page_init(struct page *page);
> >  void *memremap_pages(struct dev_pagemap *pgmap, int nid);
> > diff --git a/mm/pagewalk.c b/mm/pagewalk.c
> > index e478777..0dfb9c2 100644
> > --- a/mm/pagewalk.c
> > +++ b/mm/pagewalk.c
> > @@ -884,6 +884,12 @@ struct folio *folio_walk_start(struct folio_walk *fw,
> >  		 * support PUD mappings in VM_PFNMAP|VM_MIXEDMAP VMAs.
> >  		 */
> >  		page = pud_page(pud);
> > +
> > +		if (is_devdax_page(page)) {
> 
> Is it only devdax that can exist at PUD leaf level, not fsdax?

Correct.

> > +			spin_unlock(ptl);
> > +			goto not_found;
> > +		}
> > +
> >  		goto found;
> >  	}
> >
> > @@ -911,7 +917,8 @@ struct folio *folio_walk_start(struct folio_walk *fw,
> >  			goto pte_table;
> >  		} else if (pmd_present(pmd)) {
> >  			page = vm_normal_page_pmd(vma, addr, pmd);
> > -			if (page) {
> > +			if (page && !is_devdax_page(page) &&
> > +			    !is_fsdax_page(page)) {
> >  				goto found;
> >  			} else if ((flags & FW_ZEROPAGE) &&
> >  				    is_huge_zero_pmd(pmd)) {
> > @@ -945,7 +952,8 @@ struct folio *folio_walk_start(struct folio_walk *fw,
> >
> >  	if (pte_present(pte)) {
> >  		page = vm_normal_page(vma, addr, pte);
> > -		if (page)
> > +		if (page && !is_devdax_page(page) &&
> > +		    !is_fsdax_page(page))
> >  			goto found;
> >  		if ((flags & FW_ZEROPAGE) &&
> >  		    is_zero_pfn(pte_pfn(pte))) {
> 
> I'm probably echoing others here (and I definitely particularly like Dan's
> suggestion of a helper function here, and Jason's suggestion of explanatory
> comments), but would also be nice to not have to do this separately at each page
> table level and instead have something that you can say 'get me normal non-dax
> page at page table level <parameter>'.

I did the filtering here because I was trying to avoid unintended behavioural
changes and was being lazy by not auditing the callers. Turns out naming is
harder than doing this properly so I'm going to go with Jason and David's
suggestion and drop the filtering entirely. It will then be up to callers to
define what is "normal" for them by filtering out folio types they don't care
about. Most already do filter out zone device folios or DAX VMA's anyway, and I
will add some commentary to this effect in the respin.

> > --
> > git-series 0.9.1
>