mm/memory_hotplug: fix potential permanent lru cache disable

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@huawei.com


Fixes: d479960e ("mm: disable LRU pagevec during the migration temporarily")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Chris Goldsworthy <cgoldswo@codeaurora.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>