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* + mm-migrate-dont-split-thp-for-misplaced-numa-page.patch added to -mm tree
@ 2021-05-18 21:08 akpm
  0 siblings, 0 replies; only message in thread
From: akpm @ 2021-05-18 21:08 UTC (permalink / raw)
  To: borntraeger, gerald.schaefer, gor, hca, hughd, kirill.shutemov,
	mgorman, mhocko, mm-commits, shy828301, ying.huang, ziy

The patch titled
     Subject: mm: migrate: don't split THP for misplaced NUMA page
has been added to the -mm tree.  Its filename is

This patch should soon appear at
and later at

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From: Yang Shi <>
Subject: mm: migrate: don't split THP for misplaced NUMA page

The old behavior didn't split THP if migration is failed due to lack of
memory on the target node.  But the THP migration does split THP, so keep
the old behavior for misplaced NUMA page migration.

Signed-off-by: Yang Shi <>
Acked-by: Mel Gorman <>
Cc: Christian Borntraeger <>
Cc: Gerald Schaefer <>
Cc: Heiko Carstens <>
Cc: Huang Ying <>
Cc: Hugh Dickins <>
Cc: Kirill A. Shutemov <>
Cc: Michal Hocko <>
Cc: Vasily Gorbik <>
Cc: Zi Yan <>
Signed-off-by: Andrew Morton <>

 mm/migrate.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/migrate.c~mm-migrate-dont-split-thp-for-misplaced-numa-page
+++ a/mm/migrate.c
@@ -1422,6 +1422,7 @@ int migrate_pages(struct list_head *from
 	int swapwrite = current->flags & PF_SWAPWRITE;
 	int rc, nr_subpages;
+	bool nosplit = (reason == MR_NUMA_MISPLACED);
 	trace_mm_migrate_pages_start(mode, reason);
@@ -1493,8 +1494,9 @@ retry:
 				 * When memory is low, don't bother to try to migrate
 				 * other pages, just exit.
+				 * THP NUMA faulting doesn't split THP to retry.
-				if (is_thp) {
+				if (is_thp && !nosplit) {
 					if (!try_split_thp(page, &page2, from)) {
 						goto retry;

Patches currently in -mm which might be from are


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2021-05-18 21:08 + mm-migrate-dont-split-thp-for-misplaced-numa-page.patch added to -mm tree akpm

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