liqiong deebce9df9 mm: fix dereference a null pointer in migrate[_huge]_page_move_mapping()
Upstream doesn't use radix tree any more in migrate.c, no need this patch.

The two functions look up a slot and dereference the pointer,
If the pointer is null, the kernel would crash and dump.

The 'numad' service calls 'migrate_pages' periodically. If some slots
being replaced (Cache Eviction), the radix_tree_lookup_slot() returns
a null pointer that causes kernel crash.

"numad":  crash> bt
[exception RIP: migrate_page_move_mapping+337]

Introduce pointer checking to avoid dereference a null pointer.

Cc: <stable@vger.kernel.org> # linux-4.19.y
Signed-off-by: liqiong <liqiong@nfschina.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-23 09:10:42 +01:00
..
2020-03-25 08:06:13 +01:00
2021-03-07 12:19:02 +01:00
2019-10-11 18:20:58 +02:00
2018-12-01 09:37:33 +01:00
2018-02-06 18:32:48 -08:00