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mm: numa: add paranoid check around pte_protnone_numa

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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>
This commit is contained in:
Mel Gorman 2015-02-12 14:58:41 -08:00 committed by Linus Torvalds
parent c819f37e7e
commit c0e7cad9f2
2 changed files with 6 additions and 0 deletions
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3
mm/huge_memory.c
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@ -1262,6 +1262,9 @@ int do_huge_pmd_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)));
ptl = pmd_lock(mm, pmdp);
if (unlikely(!pmd_same(pmd, *pmdp)))
goto out_unlock;

3
mm/memory.c
View File

@ -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