From 948f581a53b704b984aa20df009f0a2b4cf7f907 Mon Sep 17 00:00:00 2001 From: Dennis Yang Date: Tue, 18 Apr 2017 15:27:06 +0800 Subject: [PATCH] dm thin: fix a memory leak when passing discard bio down dm-thin does not free the discard_parent bio after all chained sub bios finished. The following kmemleak report could be observed after pool with discard_passdown option processes discard bios in linux v4.11-rc7. To fix this, we drop the discard_parent bio reference when its endio (passdown_endio) called. unreferenced object 0xffff8803d6b29700 (size 256): comm "kworker/u8:0", pid 30349, jiffies 4379504020 (age 143002.776s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 01 00 00 00 00 00 00 f0 00 00 00 00 00 00 00 00 ................ backtrace: [] kmemleak_alloc+0x49/0xa0 [] kmem_cache_alloc+0xb4/0x100 [] mempool_alloc_slab+0x10/0x20 [] mempool_alloc+0x55/0x150 [] bio_alloc_bioset+0xb9/0x260 [] process_prepared_discard_passdown_pt1+0x40/0x1c0 [dm_thin_pool] [] break_up_discard_bio+0x1a9/0x200 [dm_thin_pool] [] process_discard_cell_passdown+0x24/0x40 [dm_thin_pool] [] process_discard_bio+0xdd/0xf0 [dm_thin_pool] [] do_worker+0xa76/0xd50 [dm_thin_pool] [] process_one_work+0x139/0x370 [] worker_thread+0x61/0x450 [] kthread+0xd6/0xf0 [] ret_from_fork+0x3f/0x70 [] 0xffffffffffffffff Cc: stable@vger.kernel.org Signed-off-by: Dennis Yang Signed-off-by: Mike Snitzer --- drivers/md/dm-thin.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index 9b3e2fcbfb1b..f90bcbf24ebc 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -1069,6 +1069,7 @@ static void passdown_endio(struct bio *bio) * to unmap (we ignore err). */ queue_passdown_pt2(bio->bi_private); + bio_put(bio); } static void process_prepared_discard_passdown_pt1(struct dm_thin_new_mapping *m) -- 2.20.1