The patch titled
Subject: migrate_pages(): fix THP failure counting for -ENOMEM
has been added to the -mm mm-unstable branch. Its filename is
migrate_pages-fix-thp-failure-counting-for-enomem.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/migrate_pages-fix-thp-failure-counting-for-enomem.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Huang Ying <ying.huang@xxxxxxxxx>
Subject: migrate_pages(): fix THP failure counting for -ENOMEM
Date: Wed, 17 Aug 2022 16:14:03 +0800
In unmap_and_move(), if the new THP cannot be allocated, -ENOMEM will be
returned, and migrate_pages() will try to split the THP unless "reason" is
MR_NUMA_MISPLACED (that is, nosplit == true). But when nosplit == true,
the THP migration failure will not be counted.
This is incorrect, so in this patch, the THP migration failure will be
counted for -ENOMEM regardless of nosplit is true or false. The nr_failed
counting isn't fixed because it's not used. Added some comments for it
per Baolin's suggestion.
Link: https://lkml.kernel.org/r/20220817081408.513338-4-ying.huang@xxxxxxxxx
Fixes: 5984fabb6e82 ("mm: move_pages: report the number of non-attempted pages")
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/mm/migrate.c~migrate_pages-fix-thp-failure-counting-for-enomem
+++ a/mm/migrate.c
@@ -1494,11 +1494,11 @@ 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 && !nosplit) {
+ if (is_thp) {
nr_thp_failed++;
- if (!try_split_thp(page, &thp_split_pages)) {
+ /* THP NUMA faulting doesn't split THP to retry. */
+ if (!nosplit && !try_split_thp(page, &thp_split_pages)) {
nr_thp_split++;
goto retry;
}
@@ -1514,6 +1514,7 @@ retry:
* the caller otherwise the page refcnt will be leaked.
*/
list_splice_init(&thp_split_pages, from);
+ /* nr_failed isn't updated for not used */
nr_thp_failed += thp_retry;
goto out;
case -EAGAIN:
_
Patches currently in -mm which might be from ying.huang@xxxxxxxxx are
memory-tiering-hot-page-selection-with-hint-page-fault-latency.patch
memory-tiering-rate-limit-numa-migration-throughput.patch
memory-tiering-adjust-hot-threshold-automatically.patch
migrate-fix-syscall-move_pages-return-value-for-failure.patch
migrate_pages-remove-unnecessary-list_safe_reset_next.patch
migrate_pages-fix-thp-failure-counting-for-enomem.patch
migrate_pages-fix-failure-counting-for-thp-subpages-retrying.patch
migrate_pages-fix-failure-counting-for-thp-on-enosys.patch
migrate_pages-fix-failure-counting-for-thp-splitting.patch
migrate_pages-fix-failure-counting-for-retry.patch
