The patch titled
Subject: mm: migrate: don't split THP for misplaced NUMA page
has been added to the -mm tree. Its filename is
mm-migrate-dont-split-thp-for-misplaced-numa-page.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-migrate-dont-split-thp-for-misplaced-numa-page.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-migrate-dont-split-thp-for-misplaced-numa-page.patch
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------------------------------------------------------
From: Yang Shi <shy828301@xxxxxxxxx>
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.
Link: https://lkml.kernel.org/r/20210518200801.7413-6-shy828301@xxxxxxxxx
Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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;
LIST_HEAD(ret_pages);
+ 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)) {
nr_thp_split++;
goto retry;
_
Patches currently in -mm which might be from shy828301@xxxxxxxxx are
mm-thp-check-total_mapcount-instead-of-page_mapcount.patch
mm-memory-add-orig_pmd-to-struct-vm_fault.patch
mm-memory-make-numa_migrate_prep-non-static.patch
mm-thp-refactor-numa-fault-handling.patch
mm-migrate-account-thp-numa-migration-counters-correctly.patch
mm-migrate-dont-split-thp-for-misplaced-numa-page.patch
mm-migrate-check-mapcount-for-thp-instead-of-refcount.patch
mm-thp-skip-make-pmd-prot_none-if-thp-migration-is-not-supported.patch
