[PATCH 6.6 184/396] dm snapshot: fix lockup in dm_exception_table_exit

Greg Kroah-Hartman
2024-04-01T16:46:27Z

From: Mikulas Patocka <mpatocka@redhat.com>

[ Upstream commit 6e7132ed3c07bd8a6ce3db4bb307ef2852b322dc ]

There was reported lockup when we exit a snapshot with many exceptions.
Fix this by adding "cond_resched" to the loop that frees the exceptions.

Reported-by: John Pittman <jpittman@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/dm-snap.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index bf7a574499a34..0ace06d1bee38 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -684,8 +684,10 @@ static void dm_exception_table_exit(struct dm_exception_table *et,
for (i = 0; i < size; i++) {
slot = et->table + i;

- hlist_bl_for_each_entry_safe(ex, pos, n, slot, hash_list)
+ hlist_bl_for_each_entry_safe(ex, pos, n, slot, hash_list) {
kmem_cache_free(mem, ex);
+ cond_resched();
+ }
}

kvfree(et->table);
--
2.43.0