[PATCH] swap: Check nrexceptional of swap cache before being freed

Huang Ying
2021-01-20T07:27:36Z

To catch the error in updating the swap cache shadow entries or their count.

Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Cc: Vlastimil Babka <vbabka@suse.cz>, Hugh Dickins <hughd@google.com>,
Cc: Mel Gorman <mgorman@techsingularity.net>,
Cc: Michal Hocko <mhocko@kernel.org>,
Cc: Dan Williams <dan.j.williams@intel.com>,
Cc: Christoph Hellwig <hch@lst.de>, Ilya Dryomov <idryomov@gmail.com>,
---
mm/swap_state.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mm/swap_state.c b/mm/swap_state.c
index d0d417efeecc..240a4f97594a 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -703,7 +703,12 @@ int init_swap_address_space(unsigned int type, unsigned long nr_pages)

void exit_swap_address_space(unsigned int type)
{
- kvfree(swapper_spaces[type]);
+ int i;
+ struct address_space *spaces = swapper_spaces[type];
+
+ for (i = 0; i < nr_swapper_spaces[type]; i++)
+ VM_BUG_ON(spaces[i].nrexceptional);
+ kvfree(spaces);
nr_swapper_spaces[type] = 0;
swapper_spaces[type] = NULL;
}
--
2.29.2