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mm: numa: do not clear PMD during PTE update scan 

If the PMD is flushed then a parallel fault in handle_mm_fault() will
enter the pmd_none and do_huge_pmd_anonymous_page() path where it'll
attempt to insert a huge zero page.  This is wasteful so the patch
avoids clearing the PMD when setting pmd_numa.

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>
hifive-unleashed-5.1
Mel Gorman 2013-12-18 17:08:36 -08:00 committed by Linus Torvalds
parent 67f87463d3
commit 5a6dac3ec5
1 changed files with 1 additions and 1 deletions
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2
mm/huge_memory.c
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@ -1539,7 +1539,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
*/
if (!is_huge_zero_page(page) &&
!pmd_numa(*pmd)) {
entry = pmdp_get_and_clear(mm, addr, pmd);
entry = *pmd;
entry = pmd_mknuma(entry);
ret = HPAGE_PMD_NR;
}