From: Andrew Morton <akpm@linux-foundation.org>
To: aarcange@redhat.com, akpm@linux-foundation.org, hughd@google.com,
linux-mm@kvack.org, mm-commits@vger.kernel.org,
peterx@redhat.com, stable@vger.kernel.org,
torvalds@linux-foundation.org
Subject: [patch 02/18] mm/swap: fix pte_same_as_swp() not removing uffd-wp bit when compare
Date: Tue, 15 Jun 2021 18:23:16 -0700 [thread overview]
Message-ID: <20210616012316.0gJpsRaYU%akpm@linux-foundation.org> (raw)
In-Reply-To: <20210615182248.9a0ba90e8e66b9f4a53c0d23@linux-foundation.org>
From: Peter Xu <peterx@redhat.com>
Subject: mm/swap: fix pte_same_as_swp() not removing uffd-wp bit when compare
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>
---
include/linux/swapops.h | 15 +++++++++++----
mm/swapfile.c | 2 +-
2 files changed, 12 insertions(+), 5 deletions(-)
--- a/include/linux/swapops.h~mm-swap-fix-pte_same_as_swp-not-removing-uffd-wp-bit-when-compare
+++ a/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_ent
{
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));
}
--- a/mm/swapfile.c~mm-swap-fix-pte_same_as_swp-not-removing-uffd-wp-bit-when-compare
+++ a/mm/swapfile.c
@@ -1900,7 +1900,7 @@ unsigned int count_swap_pages(int type,
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);
}
/*
_
next prev parent reply other threads:[~2021-06-16 1:23 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 1:22 incoming Andrew Morton
2021-06-16 1:23 ` [patch 01/18] mm,hwpoison: fix race with hugetlb page allocation Andrew Morton
2021-06-16 1:23 ` Andrew Morton [this message]
2021-06-16 1:23 ` [patch 03/18] mm/slub: clarify verification reporting Andrew Morton
2021-06-16 1:23 ` [patch 04/18] mm/slub: fix redzoning for small allocations Andrew Morton
2021-06-16 1:23 ` [patch 05/18] mm/slub: actually fix freelist pointer vs redzoning Andrew Morton
2021-06-16 1:23 ` [patch 06/18] mm/hugetlb: expand restore_reserve_on_error functionality Andrew Morton
2021-06-16 1:23 ` [patch 07/18] mm/memory-failure: make sure wait for page writeback in memory_failure Andrew Morton
2021-06-16 1:23 ` [patch 08/18] crash_core, vmcoreinfo: append 'SECTION_SIZE_BITS' to vmcoreinfo Andrew Morton
2021-06-16 1:23 ` [patch 09/18] mm/slub.c: include swab.h Andrew Morton
2021-06-16 1:23 ` [patch 10/18] mm, thp: use head page in __migration_entry_wait() Andrew Morton
2021-06-16 1:23 ` [patch 11/18] mm/thp: fix __split_huge_pmd_locked() on shmem migration entry Andrew Morton
2021-06-16 1:23 ` [patch 12/18] mm/thp: make is_huge_zero_pmd() safe and quicker Andrew Morton
2021-06-16 1:23 ` [patch 13/18] mm/thp: try_to_unmap() use TTU_SYNC for safe splitting Andrew Morton
2021-06-16 1:23 ` [patch 14/18] mm/thp: fix vma_address() if virtual address below file offset Andrew Morton
2021-06-16 1:24 ` [patch 15/18] mm/thp: fix page_address_in_vma() on file THP tails Andrew Morton
2021-06-16 1:24 ` [patch 16/18] mm/thp: unmap_mapping_page() to fix THP truncate_cleanup_page() Andrew Morton
2021-06-16 1:24 ` [patch 17/18] mm: thp: replace DEBUG_VM BUG with VM_WARN when unmap fails for split Andrew Morton
2021-06-16 1:24 ` [patch 18/18] mm/sparse: fix check_usemap_section_nr warnings Andrew Morton
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