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mm/page_vma_mapped_walk: use ptep_get_lockless() for lockless access

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When not holding the lock, there is a chance that the pte gets modified
under our feet, so we need to use the lockless API to make sure that the
entries remain consistent during the read."

Switch from ptep_get() to ptep_get_lockless() accessor for PTE reads when
no lock is taken.

[osalvador@suse.de: changelog addition]
  Link: https://lore.kernel.org/ahhNq0pFKvSKZQbR@localhost.localdomain
Link: https://lore.kernel.org/20260528075507.1821939-1-agordeev@linux.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Oscar Salvador (SUSE) <osalvador@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Harry Yoo <harry@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Alexander Gordeev
2026-05-28 09:55:07 +02:00
committed by Andrew Morton
parent 3d4f1a5416
commit 3f08b20eb1
1 changed files with 7 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
mm/page_vma_mapped.c
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@@ -41,7 +41,7 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw, pmd_t *pmdvalp,
if (!pvmw->pte)
return false;
ptent = ptep_get(pvmw->pte);
ptent = ptep_get_lockless(pvmw->pte);
if (pte_none(ptent)) {
return false;
@@ -183,6 +183,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
struct mm_struct *mm = vma->vm_mm;
unsigned long end;
spinlock_t *ptl;
pte_t pteval;
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
@@ -310,7 +311,11 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
goto restart;
}
pvmw->pte++;
} while (pte_none(ptep_get(pvmw->pte)));
if (!pvmw->ptl)
pteval = ptep_get_lockless(pvmw->pte);
else
pteval = ptep_get(pvmw->pte);
} while (pte_none(pteval));
if (!pvmw->ptl) {
spin_lock(ptl);