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mm: clear pmd_numa before invalidating

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On x86, PMD entries are similar to _PAGE_PROTNONE protection and are
handled as NUMA hinting faults.  The following two page table protection
bits are what defines them

	_PAGE_NUMA:set	_PAGE_PRESENT:clear

A PMD is considered present if any of the _PAGE_PRESENT, _PAGE_PROTNONE,
_PAGE_PSE or _PAGE_NUMA bits are set.  If pmdp_invalidate encounters a
pmd_numa, it clears the present bit leaving _PAGE_NUMA which will be
considered not present by the CPU but present by pmd_present.  The
existing caller of pmdp_invalidate should handle it but it's an
inconsistent state for a PMD.  This patch keeps the state consistent
when calling pmdp_invalidate.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: <stable@vger.kernel.org>
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 2013-12-18 17:08:34 -08:00 committed by Linus Torvalds
parent f714f4f20e
commit 67f87463d3
1 changed files with 3 additions and 0 deletions
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3
mm/pgtable-generic.c
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@ -191,6 +191,9 @@ pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp)
{
pmd_t entry = *pmdp;
if (pmd_numa(entry))
entry = pmd_mknonnuma(entry);
set_pmd_at(vma->vm_mm, address, pmdp, pmd_mknotpresent(*pmdp));
flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
}