path: root/mm/rmap.c
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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2014-06-06 10:00:01 -0400
committerShow Liu <show.liu@linaro.org>2014-06-18 12:05:31 +0800
commit5880749d5534dd03b5b9a0d216ae75d65c263cb7 (patch)
tree11180a8640b6945ea77c0ba4992aca0e18a02ef2 /mm/rmap.c
parent1f59aa3a698f0ce91ddc31ebd234d033f4d766a4 (diff)
mm: add !pte_present() check on existing hugetlb_entry callbacks
commit d4c54919ed86302094c0ca7d48a8cbd4ee753e92 upstream. 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> 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/rmap.c')
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