From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org
Cc: Alistair Popple <apopple@nvidia.com>,
David Hildenbrand <david@redhat.com>,
Jason Gunthorpe <jgg@nvidia.com>,
Dan Williams <dan.j.williams@intel.com>,
John Hubbard <jhubbard@nvidia.com>,
Oscar Salvador <osalvador@suse.de>, Peter Xu <peterx@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.12.y 3/4] mm/gup: remove dead pgmap refcounting code
Date: Wed, 11 Nov 2026 21:34:43 -0500 [thread overview]
Message-ID: <20261112023429.1348841-3-sashal@kernel.org> (raw)
In-Reply-To: <20261112023429.1348841-1-sashal@kernel.org>
From: Alistair Popple <apopple@nvidia.com>
[ Upstream commit d3f7922b929a92873e14f7c61a026a6b576e8773 ]
Prior to commit aed877c2b425 ("device/dax: properly refcount device dax
pages when mapping") ZONE_DEVICE pages were not fully reference counted
when mapped into user page tables. Instead GUP would take a reference on
the associated pgmap to ensure the results of pfn_to_page() remained
valid.
This is no longer required and most of the code was removed by commit
fd2825b0760a ("mm/gup: remove pXX_devmap usage from get_user_pages()").
Finish cleaning this up by removing the dead calls to put_dev_pagemap()
and the temporary context struct.
Link: https://lkml.kernel.org/r/20250903225926.34702-1-apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 79cb51d538ab ("mm/gup: recheck the PUD under PTL in follow_pud_mask()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
mm/gup.c | 67 ++++++++++++++++++++++----------------------------------
1 file changed, 26 insertions(+), 41 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index 914e586137a2f..b8367869f7928 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -27,11 +27,6 @@
#include "internal.h"
-struct follow_page_context {
- struct dev_pagemap *pgmap;
- unsigned int page_mask;
-};
-
static inline void sanity_check_pinned_pages(struct page **pages,
unsigned long npages)
{
@@ -624,7 +619,7 @@ static struct page *no_page_table(struct vm_area_struct *vma,
#ifdef CONFIG_PGTABLE_HAS_HUGE_LEAVES
static struct page *follow_huge_pud(struct vm_area_struct *vma,
unsigned long addr, pud_t *pudp,
- int flags, struct follow_page_context *ctx)
+ int flags, unsigned long *page_mask)
{
struct mm_struct *mm = vma->vm_mm;
struct page *page;
@@ -650,7 +645,7 @@ static struct page *follow_huge_pud(struct vm_area_struct *vma,
if (ret)
page = ERR_PTR(ret);
else
- ctx->page_mask = HPAGE_PUD_NR - 1;
+ *page_mask = HPAGE_PUD_NR - 1;
return page;
}
@@ -696,7 +691,7 @@ static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page,
static struct page *follow_huge_pmd(struct vm_area_struct *vma,
unsigned long addr, pmd_t *pmd,
unsigned int flags,
- struct follow_page_context *ctx)
+ unsigned long *page_mask)
{
struct mm_struct *mm = vma->vm_mm;
pmd_t pmdval = *pmd;
@@ -733,7 +728,7 @@ static struct page *follow_huge_pmd(struct vm_area_struct *vma,
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
- ctx->page_mask = HPAGE_PMD_NR - 1;
+ *page_mask = HPAGE_PMD_NR - 1;
return page;
}
@@ -741,7 +736,7 @@ static struct page *follow_huge_pmd(struct vm_area_struct *vma,
#else /* CONFIG_PGTABLE_HAS_HUGE_LEAVES */
static struct page *follow_huge_pud(struct vm_area_struct *vma,
unsigned long addr, pud_t *pudp,
- int flags, struct follow_page_context *ctx)
+ int flags, unsigned long *page_mask)
{
return NULL;
}
@@ -749,7 +744,7 @@ static struct page *follow_huge_pud(struct vm_area_struct *vma,
static struct page *follow_huge_pmd(struct vm_area_struct *vma,
unsigned long addr, pmd_t *pmd,
unsigned int flags,
- struct follow_page_context *ctx)
+ unsigned long *page_mask)
{
return NULL;
}
@@ -815,8 +810,7 @@ static inline bool can_follow_write_pte(pte_t pte, struct page *page,
}
static struct page *follow_page_pte(struct vm_area_struct *vma,
- unsigned long address, pmd_t *pmd, unsigned int flags,
- struct dev_pagemap **pgmap)
+ unsigned long address, pmd_t *pmd, unsigned int flags)
{
struct mm_struct *mm = vma->vm_mm;
struct folio *folio;
@@ -919,7 +913,7 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
static struct page *follow_pmd_mask(struct vm_area_struct *vma,
unsigned long address, pud_t *pudp,
unsigned int flags,
- struct follow_page_context *ctx)
+ unsigned long *page_mask)
{
pmd_t *pmd, pmdval;
spinlock_t *ptl;
@@ -933,7 +927,7 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
if (!pmd_present(pmdval))
return no_page_table(vma, flags, address);
if (likely(!pmd_leaf(pmdval)))
- return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
+ return follow_page_pte(vma, address, pmd, flags);
if (pmd_protnone(pmdval) && !gup_can_follow_protnone(vma, flags))
return no_page_table(vma, flags, address);
@@ -946,16 +940,16 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
}
if (unlikely(!pmd_leaf(pmdval))) {
spin_unlock(ptl);
- return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
+ return follow_page_pte(vma, address, pmd, flags);
}
if (pmd_trans_huge(pmdval) && (flags & FOLL_SPLIT_PMD)) {
spin_unlock(ptl);
split_huge_pmd(vma, pmd, address);
/* If pmd was left empty, stuff a page table in there quickly */
return pte_alloc(mm, pmd) ? ERR_PTR(-ENOMEM) :
- follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
+ follow_page_pte(vma, address, pmd, flags);
}
- page = follow_huge_pmd(vma, address, pmd, flags, ctx);
+ page = follow_huge_pmd(vma, address, pmd, flags, page_mask);
spin_unlock(ptl);
return page;
}
@@ -963,7 +957,7 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
static struct page *follow_pud_mask(struct vm_area_struct *vma,
unsigned long address, p4d_t *p4dp,
unsigned int flags,
- struct follow_page_context *ctx)
+ unsigned long *page_mask)
{
pud_t *pudp, pud;
spinlock_t *ptl;
@@ -976,7 +970,7 @@ static struct page *follow_pud_mask(struct vm_area_struct *vma,
return no_page_table(vma, flags, address);
if (pud_leaf(pud)) {
ptl = pud_lock(mm, pudp);
- page = follow_huge_pud(vma, address, pudp, flags, ctx);
+ page = follow_huge_pud(vma, address, pudp, flags, page_mask);
spin_unlock(ptl);
if (page)
return page;
@@ -985,13 +979,13 @@ static struct page *follow_pud_mask(struct vm_area_struct *vma,
if (unlikely(pud_bad(pud)))
return no_page_table(vma, flags, address);
- return follow_pmd_mask(vma, address, pudp, flags, ctx);
+ return follow_pmd_mask(vma, address, pudp, flags, page_mask);
}
static struct page *follow_p4d_mask(struct vm_area_struct *vma,
unsigned long address, pgd_t *pgdp,
unsigned int flags,
- struct follow_page_context *ctx)
+ unsigned long *page_mask)
{
p4d_t *p4dp, p4d;
@@ -1002,7 +996,7 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma,
if (!p4d_present(p4d) || p4d_bad(p4d))
return no_page_table(vma, flags, address);
- return follow_pud_mask(vma, address, p4dp, flags, ctx);
+ return follow_pud_mask(vma, address, p4dp, flags, page_mask);
}
/**
@@ -1010,20 +1004,16 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma,
* @vma: vm_area_struct mapping @address
* @address: virtual address to look up
* @flags: flags modifying lookup behaviour
- * @ctx: contains dev_pagemap for %ZONE_DEVICE memory pinning and a
- * pointer to output page_mask
+ * @page_mask: a pointer to output page_mask
*
* @flags can have FOLL_ flags set, defined in <linux/mm.h>
*
- * When getting pages from ZONE_DEVICE memory, the @ctx->pgmap caches
- * the device's dev_pagemap metadata to avoid repeating expensive lookups.
- *
* When getting an anonymous page and the caller has to trigger unsharing
* of a shared anonymous page first, -EMLINK is returned. The caller should
* trigger a fault with FAULT_FLAG_UNSHARE set. Note that unsharing is only
* relevant with FOLL_PIN and !FOLL_WRITE.
*
- * On output, the @ctx->page_mask is set according to the size of the page.
+ * On output, @page_mask is set according to the size of the page.
*
* Return: the mapped (struct page *), %NULL if no mapping exists, or
* an error pointer if there is a mapping to something not represented
@@ -1031,7 +1021,7 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma,
*/
static struct page *follow_page_mask(struct vm_area_struct *vma,
unsigned long address, unsigned int flags,
- struct follow_page_context *ctx)
+ unsigned long *page_mask)
{
pgd_t *pgd;
struct mm_struct *mm = vma->vm_mm;
@@ -1039,13 +1029,13 @@ static struct page *follow_page_mask(struct vm_area_struct *vma,
vma_pgtable_walk_begin(vma);
- ctx->page_mask = 0;
+ *page_mask = 0;
pgd = pgd_offset(mm, address);
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
page = no_page_table(vma, flags, address);
else
- page = follow_p4d_mask(vma, address, pgd, flags, ctx);
+ page = follow_p4d_mask(vma, address, pgd, flags, page_mask);
vma_pgtable_walk_end(vma);
@@ -1389,7 +1379,7 @@ static long __get_user_pages(struct mm_struct *mm,
{
long ret = 0, i = 0;
struct vm_area_struct *vma = NULL;
- struct follow_page_context ctx = { NULL };
+ unsigned long page_mask = 0;
if (!nr_pages)
return 0;
@@ -1427,7 +1417,7 @@ static long __get_user_pages(struct mm_struct *mm,
pages ? &page : NULL);
if (ret)
goto out;
- ctx.page_mask = 0;
+ page_mask = 0;
goto next_page;
}
@@ -1450,7 +1440,7 @@ static long __get_user_pages(struct mm_struct *mm,
}
cond_resched();
- page = follow_page_mask(vma, start, gup_flags, &ctx);
+ page = follow_page_mask(vma, start, gup_flags, &page_mask);
if (!page || PTR_ERR(page) == -EMLINK) {
ret = faultin_page(vma, start, gup_flags,
PTR_ERR(page) == -EMLINK, locked);
@@ -1483,7 +1473,7 @@ static long __get_user_pages(struct mm_struct *mm,
goto out;
}
next_page:
- page_increm = 1 + (~(start >> PAGE_SHIFT) & ctx.page_mask);
+ page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
if (page_increm > nr_pages)
page_increm = nr_pages;
@@ -1533,8 +1523,6 @@ static long __get_user_pages(struct mm_struct *mm,
nr_pages -= page_increm;
} while (nr_pages);
out:
- if (ctx.pgmap)
- put_dev_pagemap(ctx.pgmap);
return i ? i : ret;
}
@@ -2894,7 +2882,6 @@ static int gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
unsigned long end, unsigned int flags, struct page **pages,
int *nr)
{
- struct dev_pagemap *pgmap = NULL;
int ret = 0;
pte_t *ptep, *ptem;
@@ -2966,8 +2953,6 @@ static int gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
ret = 1;
pte_unmap:
- if (pgmap)
- put_dev_pagemap(pgmap);
pte_unmap(ptem);
return ret;
}
--
2.53.0
next prev parent reply other threads:[~2026-11-12 2:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-10 1:09 FAILED: patch "[PATCH] mm/gup: recheck the PUD under PTL in follow_pud_mask()" failed to apply to 6.12-stable tree Sasha Levin
2026-11-12 2:34 ` [PATCH 6.12.y 1/4] mm/gup: remove redundant check for PCI P2PDMA page Sasha Levin
2026-11-12 2:34 ` [PATCH 6.12.y 2/4] mm/gup: remove pXX_devmap usage from get_user_pages() Sasha Levin
2026-11-12 2:34 ` Sasha Levin [this message]
2026-11-12 2:34 ` [PATCH 6.12.y 4/4] mm/gup: recheck the PUD under PTL in follow_pud_mask() Sasha Levin
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