diff options
| author | Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> | 2016-07-14 12:07:35 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-07-15 14:54:27 +0900 |
| commit | 55bda43bb26d2c11eeedac742eff87a8ac34c106 (patch) | |
| tree | 7b351dcf9347f16e819f93b35fb31654533fcb47 | |
| parent | 33f4751e99601b7bfd1d66aedabd3ee9140922de (diff) | |
| download | linux-55bda43bb26d2c11eeedac742eff87a8ac34c106.tar.gz | |
mm: rmap: call page_check_address() with sync enabled to avoid racy check
The previous patch addresses the race between split_huge_pmd_address()
and someone changing the pmd. The fix is only for splitting of normal
thp (i.e. pmd-mapped thp,) and for splitting of pte-mapped thp there
still is the similar race.
For splitting pte-mapped thp, the pte's conversion is done by
try_to_unmap_one(TTU_MIGRATION). This function checks
page_check_address() to get the target pte, but it can return NULL under
some race, leading to VM_BUG_ON() in freeze_page(). Fortunately,
page_check_address() already has an argument to decide whether we do a
quick/racy check or not, so let's flip it when called from
freeze_page().
Link: http://lkml.kernel.org/r/1466990929-7452-2-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/rmap.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 0ea5d9071b32..e4b713a6ed7e 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1427,7 +1427,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, goto out; } - pte = page_check_address(page, mm, address, &ptl, 0); + pte = page_check_address(page, mm, address, &ptl, + PageTransCompound(page)); if (!pte) goto out; |