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| author | Peter Xu <peterx@redhat.com> | 2021-06-16 04:23:16 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-06-23 15:42:53 +0300 |
| commit | 12eb3c2c1a4f6e7c30de2aa0a09cb1b9e19fa9c0 (patch) | |
| tree | ebc314dd3c679fb3cf95fe566b8c330b1e1c7d85 | |
| parent | fc7fdd8c5c2ad2fe3e297698be9d4dbe4a4e0579 (diff) | |
| download | linux-12eb3c2c1a4f6e7c30de2aa0a09cb1b9e19fa9c0.tar.xz | |
mm/swap: fix pte_same_as_swp() not removing uffd-wp bit when compare
commit 099dd6878b9b12d6bbfa6bf29ce0c8ddd38f6901 upstream.
I found it by pure code review, that pte_same_as_swp() of unuse_vma()
didn't take uffd-wp bit into account when comparing ptes.
pte_same_as_swp() returning false negative could cause failure to
swapoff swap ptes that was wr-protected by userfaultfd.
Link: https://lkml.kernel.org/r/20210603180546.9083-1-peterx@redhat.com
Fixes: f45ec5ff16a7 ("userfaultfd: wp: support swap and page migration")
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org> [5.7+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/linux/swapops.h | 15 | ||||
| -rw-r--r-- | mm/swapfile.c | 2 |
2 files changed, 12 insertions, 5 deletions
diff --git a/include/linux/swapops.h b/include/linux/swapops.h index d9b7c9132c2f..6430a94c6981 100644 --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -23,6 +23,16 @@ #define SWP_TYPE_SHIFT (BITS_PER_XA_VALUE - MAX_SWAPFILES_SHIFT) #define SWP_OFFSET_MASK ((1UL << SWP_TYPE_SHIFT) - 1) +/* Clear all flags but only keep swp_entry_t related information */ +static inline pte_t pte_swp_clear_flags(pte_t pte) +{ + if (pte_swp_soft_dirty(pte)) + pte = pte_swp_clear_soft_dirty(pte); + if (pte_swp_uffd_wp(pte)) + pte = pte_swp_clear_uffd_wp(pte); + return pte; +} + /* * Store a type+offset into a swp_entry_t in an arch-independent format */ @@ -66,10 +76,7 @@ static inline swp_entry_t pte_to_swp_entry(pte_t pte) { swp_entry_t arch_entry; - if (pte_swp_soft_dirty(pte)) - pte = pte_swp_clear_soft_dirty(pte); - if (pte_swp_uffd_wp(pte)) - pte = pte_swp_clear_uffd_wp(pte); + pte = pte_swp_clear_flags(pte); arch_entry = __pte_to_swp_entry(pte); return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry)); } diff --git a/mm/swapfile.c b/mm/swapfile.c index 5256c10049b0..5af6b0f770de 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1903,7 +1903,7 @@ unsigned int count_swap_pages(int type, int free) static inline int pte_same_as_swp(pte_t pte, pte_t swp_pte) { - return pte_same(pte_swp_clear_soft_dirty(pte), swp_pte); + return pte_same(pte_swp_clear_flags(pte), swp_pte); } /* |