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
Signed-off-by: Dennis Yang <dennisyang@qnap.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 file changed