Commit 51030a53 authored by David Hildenbrand's avatar David Hildenbrand Committed by Linus Torvalds
Browse files

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 3d680bdf ("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: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarBaoquan He <bhe@redhat.com>
Reviewed-by: default avatarPankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Link: http://lkml.kernel.org/r/20200816125333.7434-3-david@redhat.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c9c510dc

mm/page_isolation.c

+5 −4
Original line number Diff line number Diff line
@@ -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);