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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2014-06-06 10:00:01 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-06 13:21:16 -0700
commitd4c54919ed86302094c0ca7d48a8cbd4ee753e92 (patch)
tree0e2f79515abf8d056d6c32912194e0c69212fad5 /fs
parentd54d14bfb49f0b61aed9f20cb84cb692566cf83b (diff)
mm: add !pte_present() check on existing hugetlb_entry callbacks
The age table walker doesn't check non-present hugetlb entry in common path, so hugetlb_entry() callbacks must check it. The reason for this behavior is that some callers want to handle it in its own way. [ I think that reason is bogus, btw - it should just do what the regular code does, which is to call the "pte_hole()" function for such hugetlb entries - Linus] However, some callers don't check it now, which causes unpredictable result, for example when we have a race between migrating hugepage and reading /proc/pid/numa_maps. This patch fixes it by adding !pte_present checks on buggy callbacks. This bug exists for years and got visible by introducing hugepage migration. ChangeLog v2: - fix if condition (check !pte_present() instead of pte_present()) Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> [ Backported to 3.15. Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org> ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/proc/task_mmu.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 442177b1119a..c4b2646b6d7c 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1351,7 +1351,7 @@ static int gather_hugetbl_stats(pte_t *pte, unsigned long hmask,
struct numa_maps *md;
struct page *page;
- if (pte_none(*pte))
+ if (!pte_present(*pte))
return 0;
page = pte_page(*pte);