Commit 5a6dac3e authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds

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: default avatarMel Gorman <mgorman@suse.de>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 67f87463
...@@ -1539,7 +1539,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, ...@@ -1539,7 +1539,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
*/ */
if (!is_huge_zero_page(page) && if (!is_huge_zero_page(page) &&
!pmd_numa(*pmd)) { !pmd_numa(*pmd)) {
entry = pmdp_get_and_clear(mm, addr, pmd); entry = *pmd;
entry = pmd_mknuma(entry); entry = pmd_mknuma(entry);
ret = HPAGE_PMD_NR; ret = HPAGE_PMD_NR;
} }
......
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