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authorMel Gorman <mgorman@suse.de>2015-02-12 14:58:41 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-12 18:54:08 -0800
commitc0e7cad9f2390087b53e26e7b98958d8793ee02d (patch)
tree76b69e566d2106fc4a28c17654928cdfafc2c7e4 /mm/memory.c
parentc819f37e7e174d68cd013abf33725b4e07ced023 (diff)
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mm: numa: add paranoid check around pte_protnone_numa
pte_protnone_numa is only safe to use after VMA checks for PROT_NONE are complete. Treating a real PROT_NONE PTE as a NUMA hinting fault is going to result in strangeness so add a check for it. BUG_ON looks like overkill but if this is hit then it's a serious bug that could result in corruption so do not even try recovering. It would have been more comprehensive to check VMA flags in pte_protnone_numa but it would have made the API ugly just for a debugging check. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Jones <davej@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Rik van Riel <riel@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c
index bf244f5..f7886ab 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3013,6 +3013,9 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
bool migrated = false;
int flags = 0;
+ /* A PROT_NONE fault should not end up here */
+ BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
+
/*
* The "pte" at this point cannot be used safely without
* validation through pte_unmap_same(). It's of NUMA type but
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