From: Zi Yan ziy@nvidia.com
mainline inclusion from mainline-v6.10-rc6 commit c6408250703530187cc6250dcd702d12a71c44f5 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAHY3K
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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...
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 ziy@nvidia.com Suggested-by: "Huang, Ying" ying.huang@intel.com Reviewed-by: "Huang, Ying" ying.huang@intel.com Cc: David Hildenbrand david@redhat.com Cc: Hugh Dickins hughd@google.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Yang Shi shy828301@gmail.com Cc: Yin Fengwei fengwei.yin@intel.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/migrate.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/mm/migrate.c b/mm/migrate.c index b5d9d8feacfa..d7d789c7a939 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1660,6 +1660,10 @@ 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() @@ -1676,6 +1680,7 @@ 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;