* [PATCH RESEND 0/3] arm64: Add PUD THP support for DAX and pfnmap
@ 2026-10-28 12:14 Jinjiang Tu
2026-10-28 12:14 ` [PATCH RESEND 1/3] mm: define generic pudp_invalidate() implementation Jinjiang Tu
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Jinjiang Tu @ 2026-10-28 12:14 UTC (permalink / raw)
To: akpm, david, ljs, catalin.marinas, will, mark.rutland,
ryan.roberts, peterx, dave.jiang, linux-arm-kernel, linux-mm
Cc: wangkefeng.wang, sunnanyong, tujinjiang
This series adds PUD THP support for arm64, enabling PUD THP for DAX
and pfnmap.
Patch 1 moves the identical pudp_invalidate() implementations from x86
and riscv to a generic location so arm64 can reuse it.
Patch 2 is a minor cleanup that simplifies pmd_special/pmd_mkspecial.
Patch 3 adds the necessary PUD page table helpers and selects
HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD.
Jinjiang Tu (3):
mm: define generic pudp_invalidate() implementation
arm64: simplify pmd_special and pmd_mkspecial
arm64: Add PUD THP support for DAX and pfnmap
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/pgtable.h | 71 +++++++++++++++-----
arch/powerpc/include/asm/book3s/64/pgtable.h | 1 +
arch/riscv/include/asm/pgtable.h | 3 -
arch/riscv/mm/pgtable.c | 9 ---
arch/x86/include/asm/pgtable.h | 3 -
arch/x86/mm/pgtable.c | 12 ----
include/linux/pgtable.h | 7 ++
mm/pgtable-generic.c | 14 ++++
9 files changed, 77 insertions(+), 44 deletions(-)
--
2.43.0
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH RESEND 1/3] mm: define generic pudp_invalidate() implementation
2026-10-28 12:14 [PATCH RESEND 0/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu
@ 2026-10-28 12:14 ` Jinjiang Tu
2026-10-28 12:14 ` [PATCH RESEND 2/3] arm64: simplify pmd_special and pmd_mkspecial Jinjiang Tu
2026-10-28 12:14 ` [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu
2 siblings, 0 replies; 6+ messages in thread
From: Jinjiang Tu @ 2026-10-28 12:14 UTC (permalink / raw)
To: akpm, david, ljs, catalin.marinas, will, mark.rutland,
ryan.roberts, peterx, dave.jiang, linux-arm-kernel, linux-mm
Cc: wangkefeng.wang, sunnanyong, tujinjiang
x86 and riscv have identical pudp_invalidate() implementations. Move it to
mm/pgtable-generic.c with the __HAVE_ARCH_PUDP_INVALIDATE override guard.
PowerPC keeps its own implementation. In the later patch, arm64 will use
the generic implementation too.
No functional change intended.
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
---
arch/powerpc/include/asm/book3s/64/pgtable.h | 1 +
arch/riscv/include/asm/pgtable.h | 3 ---
arch/riscv/mm/pgtable.c | 9 ---------
arch/x86/include/asm/pgtable.h | 3 ---
arch/x86/mm/pgtable.c | 12 ------------
include/linux/pgtable.h | 7 +++++++
mm/pgtable-generic.c | 14 ++++++++++++++
7 files changed, 22 insertions(+), 27 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index dff8790a047d..267d5e24f3b0 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -1412,6 +1412,7 @@ static inline pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm,
#define __HAVE_ARCH_PMDP_INVALIDATE
extern pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp);
+#define __HAVE_ARCH_PUDP_INVALIDATE
extern pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
pud_t *pudp);
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index d48f90140841..0126d6ca5643 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -1162,9 +1162,6 @@ static inline pud_t pud_mkinvalid(pud_t pud)
return __pud(pud_val(pud) & ~(_PAGE_PRESENT | _PAGE_PROT_NONE));
}
-extern pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
- pud_t *pudp);
-
static inline pud_t pud_modify(pud_t pud, pgprot_t newprot)
{
return pte_pud(pte_modify(pud_pte(pud), newprot));
diff --git a/arch/riscv/mm/pgtable.c b/arch/riscv/mm/pgtable.c
index 9c4427d0b187..156e385e7db4 100644
--- a/arch/riscv/mm/pgtable.c
+++ b/arch/riscv/mm/pgtable.c
@@ -154,15 +154,6 @@ pmd_t pmdp_collapse_flush(struct vm_area_struct *vma,
return pmd;
}
-pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
- pud_t *pudp)
-{
- VM_WARN_ON_ONCE(!pud_present(*pudp));
- pud_t old = pudp_establish(vma, address, pudp, pud_mkinvalid(*pudp));
-
- flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
- return old;
-}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
pte_t pte_mkwrite(pte_t pte, struct vm_area_struct *vma)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 000fc6c1ca37..ad7a40abef7d 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -1391,9 +1391,6 @@ static inline pud_t pudp_establish(struct vm_area_struct *vma,
extern pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp);
-pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
- pud_t *pudp);
-
/*
* Page table pages are page-aligned. The lower half of the top
* level is used for userspace and the top half for the kernel.
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 4a105f283cfb..591931d144f2 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -519,18 +519,6 @@ pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address,
}
#endif
-#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
- defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
-pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
- pud_t *pudp)
-{
- VM_WARN_ON_ONCE(!pud_present(*pudp));
- pud_t old = pudp_establish(vma, address, pudp, pud_mkinvalid(*pudp));
- flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
- return old;
-}
-#endif
-
/**
* reserve_top_address - Reserve a hole in the top of the kernel address space
* @reserve: Size of hole to reserve
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 780fe849ff8b..0021eaf88e1d 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1318,6 +1318,13 @@ extern pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp);
#endif
+#ifndef __HAVE_ARCH_PUDP_INVALIDATE
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
+ pud_t *pudp);
+#endif
+#endif
+
#ifndef __HAVE_ARCH_PTE_SAME
static inline int pte_same(pte_t pte_a, pte_t pte_b)
{
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 6e83ce3801b8..1b7081fc4a75 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -229,6 +229,20 @@ pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address,
}
#endif
+#ifndef __HAVE_ARCH_PUDP_INVALIDATE
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
+ pud_t *pudp)
+{
+ VM_WARN_ON_ONCE(!pud_present(*pudp));
+ pud_t old = pudp_establish(vma, address, pudp, pud_mkinvalid(*pudp));
+
+ flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
+ return old;
+}
+#endif
+#endif
+
#ifndef pmdp_collapse_flush
pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp)
--
2.43.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH RESEND 2/3] arm64: simplify pmd_special and pmd_mkspecial
2026-10-28 12:14 [PATCH RESEND 0/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu
2026-10-28 12:14 ` [PATCH RESEND 1/3] mm: define generic pudp_invalidate() implementation Jinjiang Tu
@ 2026-10-28 12:14 ` Jinjiang Tu
2026-10-28 12:14 ` [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu
2 siblings, 0 replies; 6+ messages in thread
From: Jinjiang Tu @ 2026-10-28 12:14 UTC (permalink / raw)
To: akpm, david, ljs, catalin.marinas, will, mark.rutland,
ryan.roberts, peterx, dave.jiang, linux-arm-kernel, linux-mm
Cc: wangkefeng.wang, sunnanyong, tujinjiang
Use pte_special() and pte_mkspecial() helper to simplify pmd_special()
and pmd_mkspecial(), and kill unused set_pmd_bit() and clear_pmd_bit()
helper.
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
---
arch/arm64/include/asm/pgtable.h | 19 ++-----------------
1 file changed, 2 insertions(+), 17 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 763c5a411d64..7de2487e4d35 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -240,18 +240,6 @@ static inline pte_t set_pte_bit(pte_t pte, pgprot_t prot)
return pte;
}
-static inline pmd_t clear_pmd_bit(pmd_t pmd, pgprot_t prot)
-{
- pmd_val(pmd) &= ~pgprot_val(prot);
- return pmd;
-}
-
-static inline pmd_t set_pmd_bit(pmd_t pmd, pgprot_t prot)
-{
- pmd_val(pmd) |= pgprot_val(prot);
- return pmd;
-}
-
static inline pte_t pte_mkwrite_novma(pte_t pte)
{
pte = set_pte_bit(pte, __pgprot(PTE_WRITE));
@@ -577,11 +565,8 @@ static inline pmd_t pmd_mkhuge(pmd_t pmd)
}
#ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
-#define pmd_special(pte) (!!((pmd_val(pte) & PTE_SPECIAL)))
-static inline pmd_t pmd_mkspecial(pmd_t pmd)
-{
- return set_pmd_bit(pmd, __pgprot(PTE_SPECIAL));
-}
+#define pmd_special(pmd) pte_special(pmd_pte(pmd))
+#define pmd_mkspecial(pmd) pte_pmd(pte_mkspecial(pmd_pte(pmd)))
#endif
#define __pmd_to_phys(pmd) __pte_to_phys(pmd_pte(pmd))
--
2.43.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap
2026-10-28 12:14 [PATCH RESEND 0/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu
2026-10-28 12:14 ` [PATCH RESEND 1/3] mm: define generic pudp_invalidate() implementation Jinjiang Tu
2026-10-28 12:14 ` [PATCH RESEND 2/3] arm64: simplify pmd_special and pmd_mkspecial Jinjiang Tu
@ 2026-10-28 12:14 ` Jinjiang Tu
2026-10-29 3:39 ` kernel test robot
2026-10-29 12:14 ` sashiko-bot
2 siblings, 2 replies; 6+ messages in thread
From: Jinjiang Tu @ 2026-10-28 12:14 UTC (permalink / raw)
To: akpm, david, ljs, catalin.marinas, will, mark.rutland,
ryan.roberts, peterx, dave.jiang, linux-arm-kernel, linux-mm
Cc: wangkefeng.wang, sunnanyong, tujinjiang
Add the necessary page table functions to deal with PUD THP, this enables
PUD THP for DAX and pfnmap.
I tested with CONFIG_DEBUG_VM_PGTABLE and CONFIG_PAGE_TABLE_CHECK enabled.
I wrote a test driver that invokes vmf_insert_pfn_pud() in the huge_fault
callback. Page table setup works as expected with no errors, and userspace
read/write access to the PUD-sized mapping is verified correct.
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/pgtable.h | 52 ++++++++++++++++++++++++++++++++
2 files changed, 53 insertions(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index cfef22aee709..4f988f23acfb 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -173,6 +173,7 @@ config ARM64
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
+ select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if PAGE_SIZE_4KB
select HAVE_ARCH_VMAP_STACK
select HAVE_ARM_SMCCC
select HAVE_ASM_MODVERSIONS
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7de2487e4d35..feca481b2079 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -569,6 +569,11 @@ static inline pmd_t pmd_mkhuge(pmd_t pmd)
#define pmd_mkspecial(pmd) pte_pmd(pte_mkspecial(pmd_pte(pmd)))
#endif
+#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
+#define pud_special(pud) pte_special(pud_pte(pud))
+#define pud_mkspecial(pud) pte_pud(pte_mkspecial(pud_pte(pud)))
+#endif
+
#define __pmd_to_phys(pmd) __pte_to_phys(pmd_pte(pmd))
#define __phys_to_pmd_val(phys) __phys_to_pte_val(phys)
#define pmd_pfn(pmd) ((__pmd_to_phys(pmd) & PMD_MASK) >> PAGE_SHIFT)
@@ -577,8 +582,15 @@ static inline pmd_t pmd_mkhuge(pmd_t pmd)
#define pud_young(pud) pte_young(pud_pte(pud))
#define pud_mkyoung(pud) pte_pud(pte_mkyoung(pud_pte(pud)))
#define pud_mkwrite_novma(pud) pte_pud(pte_mkwrite_novma(pud_pte(pud)))
+#define pud_mkwrite(pud) pud_mkwrite_novma(pud)
#define pud_mkvalid_k(pud) pte_pud(pte_mkvalid_k(pud_pte(pud)))
#define pud_write(pud) pte_write(pud_pte(pud))
+#define pud_dirty(pud) pte_dirty(pud_pte(pud))
+#define pud_wrprotect(pud) pte_pud(pte_wrprotect(pud_pte(pud)))
+#define pud_mkdirty(pud) pte_pud(pte_mkdirty(pud_pte(pud)))
+#define pud_mkold(pud) pte_pud(pte_mkold(pud_pte(pud)))
+#define pud_mkinvalid(pud) pte_pud(pte_mkinvalid(pud_pte(pud)))
+#define pud_mkclean(pud) pte_pud(pte_mkclean(pud_pte(pud)))
static inline pud_t pud_mkhuge(pud_t pud)
{
@@ -826,6 +838,13 @@ static inline bool pud_leaf(pud_t pud)
#define pud_user(pud) pte_user(pud_pte(pud))
#define pud_user_exec(pud) pte_user_exec(pud_pte(pud))
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+static inline int pud_trans_huge(pud_t pud)
+{
+ return pud_present(pud) && !pud_table(__pud(pud_val(pud) | PTE_VALID));
+}
+#endif
+
static inline bool pgtable_l4_enabled(void);
static inline void set_pud(pud_t *pudp, pud_t pud)
@@ -1183,6 +1202,11 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
return pte_pmd(pte_modify(pmd_pte(pmd), newprot));
}
+static inline pud_t pud_modify(pud_t pud, pgprot_t newprot)
+{
+ return pte_pud(pte_modify(pud_pte(pud), newprot));
+}
+
extern int __ptep_set_access_flags_anysz(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep,
pte_t entry, int dirty,
@@ -1207,6 +1231,16 @@ static inline int pmdp_set_access_flags(struct vm_area_struct *vma,
}
#endif
+#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
+static inline int pudp_set_access_flags(struct vm_area_struct *vma,
+ unsigned long address, pud_t *pudp,
+ pud_t entry, int dirty)
+{
+ return __ptep_set_access_flags_anysz(vma, address, (pte_t *)pudp,
+ pud_pte(entry), dirty, PUD_SIZE);
+}
+#endif
+
#ifdef CONFIG_PAGE_TABLE_CHECK
static inline bool pte_user_accessible_page(struct mm_struct *mm, unsigned long addr, pte_t pte)
{
@@ -1281,6 +1315,14 @@ static inline bool pmdp_test_and_clear_young(struct vm_area_struct *vma,
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG */
+#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
+static inline bool pudp_test_and_clear_young(struct vm_area_struct *vma,
+ unsigned long address, pud_t *pudp)
+{
+ return __ptep_test_and_clear_young(vma, address, (pte_t *)pudp);
+}
+#endif
+
static inline pte_t __ptep_get_and_clear_anysz(struct mm_struct *mm,
unsigned long address,
pte_t *ptep,
@@ -1443,6 +1485,15 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
}
#endif
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+static inline pud_t pudp_establish(struct vm_area_struct *vma,
+ unsigned long address, pud_t *pudp, pud_t pud)
+{
+ page_table_check_pud_set(vma->vm_mm, address, pudp, pud);
+ return __pud(xchg_relaxed(&pud_val(*pudp), pud_val(pud)));
+}
+#endif
+
/*
* Encode and decode a swap entry:
* bits 0-1: present (must be zero)
@@ -1517,6 +1568,7 @@ static inline void update_mmu_cache_range(struct vm_fault *vmf,
#define update_mmu_cache(vma, addr, ptep) \
update_mmu_cache_range(NULL, vma, addr, ptep, 1)
#define update_mmu_cache_pmd(vma, address, pmd) do { } while (0)
+#define update_mmu_cache_pud(vma, address, pud) do { } while (0)
#ifdef CONFIG_ARM64_PA_BITS_52
#define phys_to_ttbr(addr) (((addr) | ((addr) >> 46)) & TTBR_BADDR_MASK_52)
--
2.43.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap
2026-10-28 12:14 ` [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu
@ 2026-10-29 3:39 ` kernel test robot
2026-10-29 12:14 ` sashiko-bot
1 sibling, 0 replies; 6+ messages in thread
From: kernel test robot @ 2026-10-29 3:39 UTC (permalink / raw)
To: Jinjiang Tu, akpm, david, ljs, catalin.marinas, will,
mark.rutland, ryan.roberts, peterx, dave.jiang, linux-arm-kernel,
linux-mm
Cc: oe-kbuild-all, wangkefeng.wang, sunnanyong, tujinjiang
Hi Jinjiang,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on arm64/for-next/core powerpc/next powerpc/fixes tip/x86/core tip/x86/mm linus/master v7.3 next-20261027]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Jinjiang-Tu/mm-define-generic-pudp_invalidate-implementation/20261028-201402
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20261028121404.853944-4-tujinjiang%40huawei.com
patch subject: [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap
config: arm64-allnoconfig (https://download.01.org/0day-ci/archive/20261029/202610291125.dNGHD2Vr-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 16.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261029/202610291125.dNGHD2Vr-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202610291125.dNGHD2Vr-lkp@intel.com/
All errors (new ones prefixed by >>):
In file included from arch/arm64/include/asm/io.h:13,
from include/linux/io.h:12,
from include/linux/irq.h:20,
from include/asm-generic/hardirq.h:17,
from arch/arm64/include/asm/hardirq.h:17,
from include/linux/hardirq.h:11,
from include/linux/interrupt.h:11,
from include/linux/trace_recursion.h:5,
from include/linux/ftrace.h:10,
from arch/arm64/kernel/asm-offsets.c:13:
>> include/linux/pgtable.h:2098:19: error: redefinition of 'pud_trans_huge'
2098 | static inline int pud_trans_huge(pud_t pud)
| ^~~~~~~~~~~~~~
In file included from include/linux/pgtable.h:6:
arch/arm64/include/asm/pgtable.h:842:19: note: previous definition of 'pud_trans_huge' with type 'int(pud_t)'
842 | static inline int pud_trans_huge(pud_t pud)
| ^~~~~~~~~~~~~~
make[3]: *** [scripts/Makefile.build:185: arch/arm64/kernel/asm-offsets.s] Error 1
make[3]: Target 'prepare' not remade because of errors.
make[2]: *** [Makefile:1416: prepare0] Error 2
make[2]: Target 'prepare' not remade because of errors.
make[1]: *** [Makefile:248: __sub-make] Error 2
make[1]: Target 'prepare' not remade because of errors.
make: *** [Makefile:248: __sub-make] Error 2
make: Target 'prepare' not remade because of errors.
vim +/pud_trans_huge +2098 include/linux/pgtable.h
1501899a898dfb5 include/asm-generic/pgtable.h Dan Williams 2017-11-29 2095
a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2096 #if !defined(CONFIG_TRANSPARENT_HUGEPAGE) || \
bcd0dea5f4fb3d0 include/linux/pgtable.h Liu Shixin 2022-08-29 2097 !defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 @2098 static inline int pud_trans_huge(pud_t pud)
a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2099 {
a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2100 return 0;
a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2101 }
a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2102 #endif
a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2103
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap
2026-10-28 12:14 ` [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu
2026-10-29 3:39 ` kernel test robot
@ 2026-10-29 12:14 ` sashiko-bot
1 sibling, 0 replies; 6+ messages in thread
From: sashiko-bot @ 2026-10-29 12:14 UTC (permalink / raw)
To: Jinjiang Tu, akpm, david, ljs, catalin.marinas, will,
mark.rutland, ryan.roberts, peterx, dave.jiang, linux-mm
Cc: wangkefeng.wang, sunnanyong
Thank you for your contribution! Sashiko AI review found 4 potential issue(s) to consider:
- [High] arm64: mm: local-only TLB flush in pudp_set_access_flags() causes fault livelock
- [High] arm64: mm: missing pudp_set_wrprotect() loses HAFDBS dirty bits and triggers warning
- [High] arm64: mm: missing pudp_huge_get_and_clear() loses concurrent HAFDBS A/D updates
- [Low] arm64: mm: redefinition of pud_trans_huge() when CONFIG_TRANSPARENT_HUGEPAGE=n
--
commit 7dc812ccee714c3818da8b998f785b9073deeacd
Author: Jinjiang Tu <tujinjiang@huawei.com>
arm64: Add PUD THP support for DAX and pfnmap
This patch adds PUD transparent hugepage page table helpers on arm64 and
enables HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD for 4KB page size configurations to
support PUD THP for DAX and pfnmap mappings.
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 7de2487e4d353..feca481b20795 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
[ ... ]
> @@ -826,6 +838,13 @@ static inline bool pud_leaf(pud_t pud)
> #define pud_user(pud) pte_user(pud_pte(pud))
> #define pud_user_exec(pud) pte_user_exec(pud_pte(pud))
>
> +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
> +static inline int pud_trans_huge(pud_t pud)
> +{
> + return pud_present(pud) && !pud_table(__pud(pud_val(pud) | PTE_VALID));
> +}
> +#endif
[Severity: Low]
Will this cause a redefinition error for pud_trans_huge() when building with
CONFIG_PAGE_SIZE_4KB=y and CONFIG_TRANSPARENT_HUGEPAGE=n (for example,
allnoconfig or tinyconfig)?
In arch/arm64/Kconfig, config ARM64 selects
HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD whenever PAGE_SIZE_4KB is enabled, even
when CONFIG_TRANSPARENT_HUGEPAGE is disabled:
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if PAGE_SIZE_4KB
However, include/linux/pgtable.h includes asm/pgtable.h and then provides a
fallback definition of pud_trans_huge() whenever CONFIG_TRANSPARENT_HUGEPAGE
is not defined:
#if !defined(CONFIG_TRANSPARENT_HUGEPAGE) || \
!defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
static inline int pud_trans_huge(pud_t pud)
{
return 0;
}
#endif
Should pud_trans_huge() in arch/arm64/include/asm/pgtable.h also be guarded by
CONFIG_TRANSPARENT_HUGEPAGE (matching pmd_trans_huge() in the same file)?
[ ... ]
> @@ -1207,6 +1231,16 @@ static inline int pmdp_set_access_flags(struct vm_area_struct *vma,
> }
> #endif
>
> +#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
> +static inline int pudp_set_access_flags(struct vm_area_struct *vma,
> + unsigned long address, pud_t *pudp,
> + pud_t entry, int dirty)
> +{
> + return __ptep_set_access_flags_anysz(vma, address, (pte_t *)pudp,
> + pud_pte(entry), dirty, PUD_SIZE);
> +}
> +#endif
[Severity: High]
Can delegating pudp_set_access_flags() to __ptep_set_access_flags_anysz() lead
to an infinite spurious write page-fault livelock on remote CPUs?
In arch/arm64/mm/fault.c, __ptep_set_access_flags_anysz() only invalidates the
local CPU's TLB via TLBF_NOBROADCAST when upgrading a read-only entry to
writable/dirty, relying on remote CPUs to invalidate their stale read-only TLB
entries on a subsequent permission fault:
if (pte_same(pte, entry))
return 0;
...
/*
* Invalidate the local stale read-only entry. Remote stale entries
* may still cause page faults and be invalidated via
* flush_tlb_fix_spurious_fault().
*/
if (dirty) {
...
__flush_tlb_range(vma, address, address + pgsize, pgsize, level,
TLBF_NOWALKCACHE | TLBF_NOBROADCAST);
}
Suppose two CPUs fault in a shared PUD mapping as hardware read-only
(PTE_RDONLY=1, such as on an initial read fault for fsdax, a PFNMAP/devdax
mapping on a CPU without hardware DBM, or after copy_huge_pud() write-protects
the PUD), and CPU A then writes to the mapping. CPU A updates *pudp via
wp_huge_pud() -> insert_pud() -> pudp_set_access_flags() or
huge_pud_set_accessed() -> touch_pud() -> pudp_set_access_flags(), flushing
only CPU A's local TLB.
When CPU B subsequently writes to the same PUD range, it takes a permission
fault from its stale read-only local TLB entry and enters:
__handle_mm_fault()
huge_pud_set_accessed()
touch_pud()
pudp_set_access_flags()
__ptep_set_access_flags_anysz()
Because *pudp in memory already matches entry (with PTE_AF, PTE_DIRTY, and
PTE_WRITE set and PTE_RDONLY cleared), pte_same(pte, entry) is true and
__ptep_set_access_flags_anysz() returns 0 without flushing CPU B's TLB.
Unlike the PTE and PMD paths, which call flush_tlb_fix_spurious_fault() and
flush_tlb_fix_spurious_fault_pmd() when ptep_set_access_flags() or
pmdp_set_access_flags() returns 0, neither touch_pud(),
huge_pud_set_accessed(), __handle_mm_fault(), nor insert_pud() performs a
local TLB flush on a spurious PUD fault. Wouldn't CPU B return to userspace
with the stale read-only PUD TLB entry still in place and fault in an infinite
loop?
[ ... ]
> @@ -1281,6 +1315,14 @@ static inline bool pmdp_test_and_clear_young(struct vm_area_struct *vma,
> }
> #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG */
>
> +#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
> +static inline bool pudp_test_and_clear_young(struct vm_area_struct *vma,
> + unsigned long address, pud_t *pudp)
> +{
> + return __ptep_test_and_clear_young(vma, address, (pte_t *)pudp);
> +}
> +#endif
> +
> static inline pte_t __ptep_get_and_clear_anysz(struct mm_struct *mm,
> unsigned long address,
> pte_t *ptep,
[Severity: High]
Should arm64 also define __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR and implement
pudp_huge_get_and_clear() via __ptep_get_and_clear_anysz(..., PUD_SIZE)?
__ptep_get_and_clear_anysz() in arch/arm64/include/asm/pgtable.h already uses
an atomic xchg_relaxed() and has a PUD_SIZE case for
page_table_check_pud_clear(). Without an arch definition of
pudp_huge_get_and_clear(), arm64 falls back to the generic implementation in
include/linux/pgtable.h:
#ifndef __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR
static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm,
unsigned long address,
pud_t *pudp)
{
pud_t pud = *pudp;
pud_clear(pudp);
page_table_check_pud_clear(mm, address, pud);
return pud;
}
#endif
When splitting a DAX PUD via split_huge_pud() -> __split_huge_pud_locked() ->
pudp_huge_clear_flush() -> pudp_huge_get_and_clear(), __split_huge_pud_locked()
propagates the dirty and young bits from old_pud to the folio:
old_pud = pudp_huge_clear_flush(vma, haddr, pud);
if (!vma_is_dax(vma))
return;
page = pud_page(old_pud);
folio = page_folio(page);
if (!folio_test_dirty(folio) && pud_dirty(old_pud))
folio_mark_dirty(folio);
if (!folio_test_referenced(folio) && pud_young(old_pud))
folio_set_referenced(folio);
On systems with FEAT_HAFDBS, couldn't a concurrent hardware access or dirty
state update between the non-atomic read of *pudp and pud_clear(pudp) be lost?
[ ... ]
> @@ -1443,6 +1485,15 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
> }
> #endif
>
> +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
> +static inline pud_t pudp_establish(struct vm_area_struct *vma,
> + unsigned long address, pud_t *pudp, pud_t pud)
> +{
> + page_table_check_pud_set(vma->vm_mm, address, pudp, pud);
> + return __pud(xchg_relaxed(&pud_val(*pudp), pud_val(pud)));
> +}
> +#endif
[Severity: High]
Is __HAVE_ARCH_PUDP_SET_WRPROTECT with pudp_set_wrprotect() also needed here,
matching pmdp_set_wrprotect() right above pmdp_establish()?
Without an architecture-specific pudp_set_wrprotect() wrapping
__ptep_set_wrprotect(), arm64 uses the generic fallback in
include/linux/pgtable.h:
static inline void pudp_set_wrprotect(struct mm_struct *mm,
unsigned long address, pud_t *pudp)
{
pud_t old_pud = *pudp;
set_pud_at(mm, address, pudp, pud_wrprotect(old_pud));
}
When fork() copies a COW PUD via copy_page_range() -> copy_p4d_range() ->
copy_pud_range() -> copy_huge_pud() -> pudp_set_wrprotect():
1. The non-atomic read of *pudp followed by set_pud_at() races with hardware
AF/DBM updates (FEAT_HAFDBS), unlike __ptep_set_wrprotect() which uses a
cmpxchg_relaxed() loop to atomically transfer hardware dirty state to
PTE_DIRTY while setting PTE_RDONLY and clearing PTE_WRITE.
2. Updating a live valid PUD in place via set_pud_at() -> __set_ptes_anysz()
calls __check_safe_pte_update() in arch/arm64/mm/mmu.c, which triggers
VM_WARN_ONCE() when the entry is old or writable-clean on a live mm:
VM_WARN_ONCE(!pte_young(pte),
"%s: racy access flag clearing: %s -> %s",
__func__, pte_str_old, pte_str);
VM_WARN_ONCE(pte_write(old_pte) && !pte_dirty(pte),
"%s: racy dirty state clearing: %s -> %s",
__func__, pte_str_old, pte_str);
3. set_pud_at() also runs __sync_cache_and_tags() across PUD_SIZE >> PAGE_SHIFT
(262,144) pages unnecessarily when only write-protecting an existing entry.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261028121404.853944-1-tujinjiang@huawei.com?part=3
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Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2026-10-28 12:14 [PATCH RESEND 0/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu
2026-10-28 12:14 ` [PATCH RESEND 1/3] mm: define generic pudp_invalidate() implementation Jinjiang Tu
2026-10-28 12:14 ` [PATCH RESEND 2/3] arm64: simplify pmd_special and pmd_mkspecial Jinjiang Tu
2026-10-28 12:14 ` [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu
2026-10-29 3:39 ` kernel test robot
2026-10-29 12:14 ` sashiko-bot
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