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Message-ID: <20240618134151.29214-1-zi.yan@sent.com>
Date: Tue, 18 Jun 2024 09:41:51 -0400
From: Zi Yan <zi.yan@...t.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Hugh Dickins <hughd@...gle.com>,
"Huang, Ying" <ying.huang@...el.com>,
linux-mm@...ck.org
Cc: Zi Yan <ziy@...dia.com>,
"Matthew Wilcox (Oracle)" <willy@...radead.org>,
Yang Shi <shy828301@...il.com>,
David Hildenbrand <david@...hat.com>,
Yin Fengwei <fengwei.yin@...el.com>,
linux-kernel@...r.kernel.org
Subject: [PATCH] mm/migrate: make migrate_pages_batch() stats consistent.
From: Zi Yan <ziy@...dia.com>
As Ying pointed out in [1], stats->nr_thp_failed needs to be updated to
avoid stats inconsistency between MIGRATE_SYNC and MIGRATE_ASYNC when
calling migrate_pages_batch().
[1] https://lore.kernel.org/linux-mm/87msnq7key.fsf@yhuang6-desk2.ccr.corp.intel.com/
Suggested-by: "Huang, Ying" <ying.huang@...el.com>
Signed-off-by: Zi Yan <ziy@...dia.com>
---
mm/migrate.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/mm/migrate.c b/mm/migrate.c
index 2cc5a68f6843..20cb9f5f7446 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1659,6 +1659,10 @@ static int migrate_pages_batch(struct list_head *from,
* migrate_pages() may report success with (split but
* unmigrated) pages still on its fromlist; whereas it
* always reports success when its fromlist is empty.
+ * stats->nr_thp_failed should be increased too,
+ * otherwise stats inconsistency will happen when
+ * migrate_pages_batch is called via migrate_pages()
+ * with MIGRATE_SYNC and MIGRATE_ASYNC.
*
* Only check it without removing it from the list.
* Since the folio can be on deferred_split_scan()
@@ -1675,6 +1679,7 @@ static int migrate_pages_batch(struct list_head *from,
!list_empty(&folio->_deferred_list)) {
if (try_split_folio(folio, split_folios) == 0) {
nr_failed++;
+ stats->nr_thp_failed += is_thp;
stats->nr_thp_split += is_thp;
stats->nr_split++;
continue;
base-commit: 14d7c92f8df9c0964ae6f8b813c1b3ac38120825
--
2.43.0
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