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>
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@ -1539,7 +1539,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
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*/
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if (!is_huge_zero_page(page) &&
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!pmd_numa(*pmd)) {
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entry = pmdp_get_and_clear(mm, addr, pmd);
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entry = *pmd;
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entry = pmd_mknuma(entry);
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ret = HPAGE_PMD_NR;
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}
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