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>
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 51f0693..420826e 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1539,7 +1539,7 @@
*/
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;
}