diff options
| author | Theodore Ts'o <tytso@mit.edu> | 2014-07-12 23:32:24 +0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2014-07-12 23:32:24 +0400 |
| commit | 3f1f9b851311a76226140b55b1ea22111234a7c2 (patch) | |
| tree | c2c4bb1a1790cf33b0bdf796a23b2fae268c1bd3 | |
| parent | f9ae9cf5d72b3926ca48ea60e15bdbb840f42372 (diff) | |
| download | linux-3f1f9b851311a76226140b55b1ea22111234a7c2.tar.xz | |
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>
| -rw-r--r-- | fs/ext4/extents_status.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c index 3f5c188953a4..0b7e28e7eaa4 100644 --- a/fs/ext4/extents_status.c +++ b/fs/ext4/extents_status.c @@ -966,10 +966,10 @@ retry: continue; } - if (ei->i_es_lru_nr == 0 || ei == locked_ei) + if (ei->i_es_lru_nr == 0 || ei == locked_ei || + !write_trylock(&ei->i_es_lock)) continue; - write_lock(&ei->i_es_lock); shrunk = __es_try_to_reclaim_extents(ei, nr_to_scan); if (ei->i_es_lru_nr == 0) list_del_init(&ei->i_es_lru); |