superrob1500
/
mirror-linux
mirror of https://github.com/torvalds/linux
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

mm: userfaultfd: move_pages_pte() use pte_offset_map_rw_nolock() 

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
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>
pull/1085/head
Qi Zheng 2024-09-26 14:46:24 +08:00 committed by Andrew Morton
parent 04965da7a4
commit e9c74b5431
1 changed files with 12 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
mm/userfaultfd.c
View File

@ -1135,7 +1135,7 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
spinlock_t *src_ptl, *dst_ptl; spinlock_t *src_ptl, *dst_ptl;
pte_t *src_pte = NULL; pte_t *src_pte = NULL;
pte_t *dst_pte = NULL; pte_t *dst_pte = NULL;
pmd_t dummy_pmdval;
struct folio *src_folio = NULL; struct folio *src_folio = NULL;
struct anon_vma *src_anon_vma = NULL; struct anon_vma *src_anon_vma = NULL;
struct mmu_notifier_range range; struct mmu_notifier_range range;
@ -1146,7 +1146,14 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
src_addr, src_addr + PAGE_SIZE); src_addr, src_addr + PAGE_SIZE);
mmu_notifier_invalidate_range_start(&range); mmu_notifier_invalidate_range_start(&range);
retry: 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 */ /* Retry if a huge pmd materialized from under us */
if (unlikely(!dst_pte)) { if (unlikely(!dst_pte)) {
@ -1154,7 +1161,9 @@ retry:
goto out; 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 * We held the mmap_lock for reading so MADV_DONTNEED