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UPSTREAM: mm: userfaultfd: move_pages_pte() use pte_offset_map_rw_nolock()

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In move_pages_pte(), we may modify the dst_pte and src_pte after acquiring
the ptl, so convert it to using pte_offset_map_rw_nolock().  But since we
will use pte_same() to detect the change of the pte entry, there is no
need to get pmdval, so just pass a dummy variable to it.

Link: https://lkml.kernel.org/r/1530e8fdbfc72eacf3b095babe139ce3d715600a.1727332572.git.zhengqi.arch@bytedance.com
Change-Id: I0e201fd5fbc01a60e5fac307b2a2c4b52822f58d
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit e9c74b5431632d2ca60725ffff6fc1fe2b80f246)
Bug: 393446550
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
This commit is contained in:
Qi Zheng
2024-09-26 14:46:24 +08:00
committed by Treehugger Robot
parent 8e62940ae9
commit d5d31cd5ce
1 changed files with 12 additions and 3 deletions
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mm/userfaultfd.c
+12 -3
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@@ -1141,7 +1141,7 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
spinlock_t *src_ptl, *dst_ptl;
pte_t *src_pte = NULL;
pte_t *dst_pte = NULL;
pmd_t dummy_pmdval;
struct folio *src_folio = NULL;
struct anon_vma *src_anon_vma = NULL;
struct mmu_notifier_range range;
@@ -1152,7 +1152,14 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
src_addr, src_addr + PAGE_SIZE);
mmu_notifier_invalidate_range_start(&range);
retry:
dst_pte = pte_offset_map_nolock(mm, dst_pmd, dst_addr, &dst_ptl);
/*
* Use the maywrite version to indicate that dst_pte will be modified,
* but since we will use pte_same() to detect the change of the pte
* entry, there is no need to get pmdval, so just pass a dummy variable
* to it.
*/
dst_pte = pte_offset_map_rw_nolock(mm, dst_pmd, dst_addr, &dummy_pmdval,
&dst_ptl);
/* Retry if a huge pmd materialized from under us */
if (unlikely(!dst_pte)) {
@@ -1160,7 +1167,9 @@ retry:
goto out;
}
src_pte = pte_offset_map_nolock(mm, src_pmd, src_addr, &src_ptl);
/* same as dst_pte */
src_pte = pte_offset_map_rw_nolock(mm, src_pmd, src_addr, &dummy_pmdval,
&src_ptl);
/*
* We held the mmap_lock for reading so MADV_DONTNEED