From: Zi Yan Date: Tue, 18 Jun 2024 13:41:51 +0000 (-0400) Subject: mm/migrate: make migrate_pages_batch() stats consistent X-Git-Tag: v6.10-rc6~37^2~3 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=c6408250703530187cc6250dcd702d12a71c44f5;p=linux-block.git mm/migrate: make migrate_pages_batch() stats consistent 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(). Because if not, when migrate_pages_batch() is called via migrate_pages(MIGRATE_ASYNC), nr_thp_failed will not be increased and when migrate_pages_batch() is called via migrate_pages(MIGRATE_SYNC*), nr_thp_failed will be increase in migrate_pages_sync() by stats->nr_thp_failed += astats.nr_thp_split. [1] https://lore.kernel.org/linux-mm/87msnq7key.fsf@yhuang6-desk2.ccr.corp.intel.com/ Link: https://lkml.kernel.org/r/20240620012712.19804-1-zi.yan@sent.com Link: https://lkml.kernel.org/r/20240618134151.29214-1-zi.yan@sent.com Fixes: 7262f208ca68 ("mm/migrate: split source folio if it is on deferred split list") Signed-off-by: Zi Yan Suggested-by: "Huang, Ying" Reviewed-by: "Huang, Ying" Cc: David Hildenbrand Cc: Hugh Dickins Cc: Matthew Wilcox (Oracle) Cc: Yang Shi Cc: Yin Fengwei Signed-off-by: Andrew Morton --- 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;