From: Mel Gorman <mgorman@xxxxxxx>
Subject: 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@xxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Alex Thorlton <athorlton@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/huge_memory.c~mm-numa-do-not-clear-pmd-during-pte-update-scan mm/huge_memory.c
--- a/mm/huge_memory.c~mm-numa-do-not-clear-pmd-during-pte-update-scan
+++ a/mm/huge_memory.c
@@ -1539,7 +1539,7 @@ int change_huge_pmd(struct vm_area_struc
*/
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;
}
_
--
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