From 51030a53d81e308f55e0e1d2048d23d8c8d16e5b Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Tue, 13 Oct 2020 16:55:21 -0700 Subject: [PATCH] mm/page_isolation: exit early when pageblock is isolated in set_migratetype_isolate() Right now, if we have two isolations racing on a pageblock that's in the MOVABLE zone, we would trigger the WARN_ON_ONCE(). Let's just return directly, simplifying error handling. The change was introduced in commit 3d680bdf60a5 ("mm/page_isolation: fix potential warning from user"). As far as I can see, we currently don't have alloc_contig_range() users that use the ZONE_MOVABLE (anymore), so it's currently more a cleanup and a preparation for the future than a fix. Signed-off-by: David Hildenbrand Signed-off-by: Andrew Morton Reviewed-by: Baoquan He Reviewed-by: Pankaj Gupta Acked-by: Mike Kravetz Cc: Michal Hocko Cc: Michael S. Tsirkin Cc: Qian Cai Cc: Jason Wang Cc: Mike Rapoport Link: http://lkml.kernel.org/r/20200816125333.7434-3-david@redhat.com Signed-off-by: Linus Torvalds --- mm/page_isolation.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/page_isolation.c b/mm/page_isolation.c index 63a3db10a8c0..ad3aa7ac59a7 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -29,10 +29,12 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_ /* * We assume the caller intended to SET migrate type to isolate. * If it is already set, then someone else must have raced and - * set it before us. Return -EBUSY + * set it before us. */ - if (is_migrate_isolate_page(page)) - goto out; + if (is_migrate_isolate_page(page)) { + spin_unlock_irqrestore(&zone->lock, flags); + return -EBUSY; + } /* * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. @@ -52,7 +54,6 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_ ret = 0; } -out: spin_unlock_irqrestore(&zone->lock, flags); if (!ret) { drain_all_pages(zone);