ext4: fix a potential deadlock in __ext4_es_shrink()
This fixes the following lockdep complaint: [ INFO: possible circular locking dependency detected ] 3.16.0-rc2-mm1+ #7 Tainted: G O ------------------------------------------------------- kworker/u24:0/4356 is trying to acquire lock: (&(&sbi->s_es_lru_lock)->rlock){+.+.-.}, at: [<ffffffff81285fff>] __ext4_es_shrink+0x4f/0x2e0 but task is already holding lock: (&ei->i_es_lock){++++-.}, at: [<ffffffff81286961>] ext4_es_insert_extent+0x71/0x180 which lock already depends on the new lock. Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ei->i_es_lock); lock(&(&sbi->s_es_lru_lock)->rlock); lock(&ei->i_es_lock); lock(&(&sbi->s_es_lru_lock)->rlock); *** DEADLOCK *** 6 locks held by kworker/u24:0/4356: #0: ("writeback"){.+.+.+}, at: [<ffffffff81071d00>] process_one_work+0x180/0x560 #1: ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff81071d00>] process_one_work+0x180/0x560 #2: (&type->s_umount_key#22){++++++}, at: [<ffffffff811a9c74>] grab_super_passive+0x44/0x90 #3: (jbd2_handle){+.+...}, at: [<ffffffff812979f9>] start_this_handle+0x189/0x5f0 #4: (&ei->i_data_sem){++++..}, at: [<ffffffff81247062>] ext4_map_blocks+0x132/0x550 #5: (&ei->i_es_lock){++++-.}, at: [<ffffffff81286961>] ext4_es_insert_extent+0x71/0x180 stack backtrace: CPU: 0 PID: 4356 Comm: kworker/u24:0 Tainted: G O 3.16.0-rc2-mm1+ #7 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Workqueue: writeback bdi_writeback_workfn (flush-253:0) ffffffff8213dce0 ffff880014b07538 ffffffff815df0bb 0000000000000007 ffffffff8213e040 ffff880014b07588 ffffffff815db3dd ffff880014b07568 ffff880014b07610 ffff88003b868930 ffff88003b868908 ffff88003b868930 Call Trace: [<ffffffff815df0bb>] dump_stack+0x4e/0x68 [<ffffffff815db3dd>] print_circular_bug+0x1fb/0x20c [<ffffffff810a7a3e>] __lock_acquire+0x163e/0x1d00 [<ffffffff815e89dc>] ? retint_restore_args+0xe/0xe [<ffffffff815ddc7b>] ? __slab_alloc+0x4a8/0x4ce [<ffffffff81285fff>] ? __ext4_es_shrink+0x4f/0x2e0 [<ffffffff810a8707>] lock_acquire+0x87/0x120 [<ffffffff81285fff>] ? __ext4_es_shrink+0x4f/0x2e0 [<ffffffff8128592d>] ? ext4_es_free_extent+0x5d/0x70 [<ffffffff815e6f09>] _raw_spin_lock+0x39/0x50 [<ffffffff81285fff>] ? __ext4_es_shrink+0x4f/0x2e0 [<ffffffff8119760b>] ? kmem_cache_alloc+0x18b/0x1a0 [<ffffffff81285fff>] __ext4_es_shrink+0x4f/0x2e0 [<ffffffff812869b8>] ext4_es_insert_extent+0xc8/0x180 [<ffffffff812470f4>] ext4_map_blocks+0x1c4/0x550 [<ffffffff8124c4c4>] ext4_writepages+0x6d4/0xd00 ... Reported-by:Minchan Kim <minchan@kernel.org> Signed-off-by:
Theodore Ts'o <tytso@mit.edu> Reported-by:
Minchan Kim <minchan@kernel.org> Cc: stable@vger.kernel.org Cc: Zheng Liu <gnehzuil.liu@gmail.com>
parent
f9ae9cf5
Please register or sign in to comment