From: Mike Snitzer <snitzer@xxxxxxxxxx> commit 722d90822321497e2837cfc9000202e256e6b32f upstream. issue_discard() passes GFP_NOWAIT to __blkdev_issue_discard() despite its code assuming bio_alloc() always succeeds. Commit 3dba53a958a75 ("dm thin: use __blkdev_issue_discard for async discard support") clearly shows where things went bad: Before commit 3dba53a958a75, dm-thin.c's open-coded __blkdev_issue_discard_async() properly handled using GFP_NOWAIT. Unfortunately __blkdev_issue_discard() doesn't and it was missed during review. Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/md/dm-thin.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -399,8 +399,7 @@ static int issue_discard(struct discard_ sector_t s = block_to_sectors(tc->pool, data_b); sector_t len = block_to_sectors(tc->pool, data_e - data_b); - return __blkdev_issue_discard(tc->pool_dev->bdev, s, len, GFP_NOWAIT, - &op->bio); + return __blkdev_issue_discard(tc->pool_dev->bdev, s, len, GFP_NOIO, &op->bio); } static void end_discard(struct discard_op *op, int r)