| From 6b64fcb32ebf106de2ff2d42bec4d9d9d3a0e19a Mon Sep 17 00:00:00 2001 |
| From: Dennis Yang <dennisyang@qnap.com> |
| Date: Tue, 18 Apr 2017 15:27:06 +0800 |
| Subject: [PATCH] dm thin: fix a memory leak when passing discard bio down |
| |
| commit 948f581a53b704b984aa20df009f0a2b4cf7f907 upstream. |
| |
| 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: |
| [<ffffffff81a5efd9>] kmemleak_alloc+0x49/0xa0 |
| [<ffffffff8114ec34>] kmem_cache_alloc+0xb4/0x100 |
| [<ffffffff8110eec0>] mempool_alloc_slab+0x10/0x20 |
| [<ffffffff8110efa5>] mempool_alloc+0x55/0x150 |
| [<ffffffff81374939>] bio_alloc_bioset+0xb9/0x260 |
| [<ffffffffa018fd20>] process_prepared_discard_passdown_pt1+0x40/0x1c0 [dm_thin_pool] |
| [<ffffffffa018b409>] break_up_discard_bio+0x1a9/0x200 [dm_thin_pool] |
| [<ffffffffa018b484>] process_discard_cell_passdown+0x24/0x40 [dm_thin_pool] |
| [<ffffffffa018b24d>] process_discard_bio+0xdd/0xf0 [dm_thin_pool] |
| [<ffffffffa018ecf6>] do_worker+0xa76/0xd50 [dm_thin_pool] |
| [<ffffffff81086239>] process_one_work+0x139/0x370 |
| [<ffffffff810867b1>] worker_thread+0x61/0x450 |
| [<ffffffff8108b316>] kthread+0xd6/0xf0 |
| [<ffffffff81a6cd1f>] ret_from_fork+0x3f/0x70 |
| [<ffffffffffffffff>] 0xffffffffffffffff |
| |
| Cc: stable@vger.kernel.org |
| Signed-off-by: Dennis Yang <dennisyang@qnap.com> |
| Signed-off-by: Mike Snitzer <snitzer@redhat.com> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c |
| index d1c05c12a9db..be869a990e38 100644 |
| --- a/drivers/md/dm-thin.c |
| +++ b/drivers/md/dm-thin.c |
| @@ -1070,6 +1070,7 @@ 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) |
| -- |
| 2.12.0 |
| |