[PATCH 5.13 019/113] mm/memory_hotplug: fix potential permanent lru cache disable

From: Greg Kroah-Hartman
Date: Wed Sep 01 2021 - 08:47:16 EST

From: Miaohe Lin <linmiaohe@xxxxxxxxxx>

commit 946746d1ad921e5f493b536533dda02ea22ca609 upstream.

If offline_pages failed after lru_cache_disable(), it forgot to do
lru_cache_enable() in error path. So we would have lru cache disabled
permanently in this case.

Link: https://lkml.kernel.org/r/20210821094246.10149-3-linmiaohe@xxxxxxxxxx
Fixes: d479960e44f2 ("mm: disable LRU pagevec during the migration temporarily")
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Chris Goldsworthy <cgoldswo@xxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
mm/memory_hotplug.c | 1 +
1 file changed, 1 insertion(+)

--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1854,6 +1854,7 @@ failed_removal_isolated:
undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
memory_notify(MEM_CANCEL_OFFLINE, &arg);
+ lru_cache_enable();
pr_debug("memory offlining [mem %#010llx-%#010llx] failed due to %s\n",