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mm: fix apply_to_existing_page_range()

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In the case of apply_to_existing_page_range(), apply_to_pte_range() is
reached with 'create' set to false.  When !create, the loop over the PTE
page table is broken.

apply_to_pte_range() will only move to the next PTE entry if 'create' is
true or if the current entry is not pte_none().

This means that the user of apply_to_existing_page_range() will not have
'fn' called for any entries after the first pte_none() in the PTE page
table.

Fix the loop logic in apply_to_pte_range().

There are no known runtime issues from this, but the fix is trivial enough
for stable@ even without a known buggy user. 

Link: https://lkml.kernel.org/r/20250409094043.1629234-1-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Fixes: be1db4753ee6 ("mm/memory.c: add apply_to_existing_page_range() helper")
Cc: Daniel Axtens <dja@axtens.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2025-04-09 12:40:43 +03:00 committed by Andrew Morton
parent 92868577d0
commit a995199384
1 changed files with 2 additions and 2 deletions
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4
mm/memory.c
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@ -2938,11 +2938,11 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
if (fn) {
do {
if (create || !pte_none(ptep_get(pte))) {
err = fn(pte++, addr, data);
err = fn(pte, addr, data);
if (err)
break;
}
} while (addr += PAGE_SIZE, addr != end);
} while (pte++, addr += PAGE_SIZE, addr != end);
}
*mask |= PGTBL_PTE_MODIFIED;