• Dennis Yang's avatar
    dm thin: fix a memory leak when passing discard bio down · 948f581a
    Dennis Yang authored
    
    
    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: default avatarDennis Yang <dennisyang@qnap.com>
    Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
    948f581a
dm-thin.c 110 KB