[dm-devel] 3.15-rc4: circular locking dependency triggered by dm-multipath

[Bart Van Assche]

Hello,

Has anyone else perhaps already run into this ?

Thanks,

Bart.

======================================================
[ INFO: possible circular locking dependency detected ]
3.15.0-rc4-debug+ #1 Not tainted
-------------------------------------------------------
multipathd/10364 is trying to acquire lock:
 (&(&q->__queue_lock)->rlock){-.-...}, at: [<ffffffffa043bff3>] dm_table_run_md_queue_async+0x33/0x60 [dm_mod]

but task is already holding lock:
 (&(&m->lock)->rlock){..-...}, at: [<ffffffffa077a647>] queue_if_no_path+0x27/0xc0 [dm_multipath]

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&(&m->lock)->rlock){..-...}:
       [<ffffffff810a56c3>] lock_acquire+0x93/0x1c0
       [<ffffffff814ae8eb>] _raw_spin_lock+0x3b/0x50
       [<ffffffffa043a3e9>] dm_blk_open+0x19/0x80 [dm_mod]
       [<ffffffff811cbc41>] __blkdev_get+0xd1/0x4c0
       [<ffffffff811cc215>] blkdev_get+0x1e5/0x380
       [<ffffffff811cc45b>] blkdev_open+0x5b/0x80
       [<ffffffff8118a12e>] do_dentry_open.isra.15+0x1de/0x2a0
       [<ffffffff8118a300>] finish_open+0x30/0x40
       [<ffffffff8119c44d>] do_last.isra.61+0xa5d/0x1200
       [<ffffffff8119cca7>] path_openat+0xb7/0x620
       [<ffffffff8119d88a>] do_filp_open+0x3a/0x90
       [<ffffffff8118bb4e>] do_sys_open+0x12e/0x210
       [<ffffffff8118bc4e>] SyS_open+0x1e/0x20
       [<ffffffff814b84e2>] tracesys+0xd0/0xd5

-> #0 (&(&q->__queue_lock)->rlock){-.-...}:
       [<ffffffff810a4c46>] __lock_acquire+0x1716/0x1a00
       [<ffffffff810a56c3>] lock_acquire+0x93/0x1c0
       [<ffffffff814aea56>] _raw_spin_lock_irqsave+0x46/0x60
       [<ffffffffa043bff3>] dm_table_run_md_queue_async+0x33/0x60 [dm_mod]
       [<ffffffffa077a692>] queue_if_no_path+0x72/0xc0 [dm_multipath]
       [<ffffffffa077a6f9>] multipath_presuspend+0x19/0x20 [dm_multipath]
       [<ffffffffa043d34a>] dm_table_presuspend_targets+0x4a/0x60 [dm_mod]
       [<ffffffffa043ad5d>] dm_suspend+0x6d/0x1f0 [dm_mod]
       [<ffffffffa043ff63>] dev_suspend+0x1c3/0x220 [dm_mod]
       [<ffffffffa0440759>] ctl_ioctl+0x269/0x500 [dm_mod]
       [<ffffffffa0440a03>] dm_ctl_ioctl+0x13/0x20 [dm_mod]
       [<ffffffff811a04c0>] do_vfs_ioctl+0x300/0x520
       [<ffffffff811a0721>] SyS_ioctl+0x41/0x80
       [<ffffffff814b84e2>] tracesys+0xd0/0xd5

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&(&m->lock)->rlock);
                               lock(&(&q->__queue_lock)->rlock);
                               lock(&(&m->lock)->rlock);
  lock(&(&q->__queue_lock)->rlock);

 *** DEADLOCK ***

2 locks held by multipathd/10364:
 #0:  (&md->suspend_lock){+.+...}, at: [<ffffffffa043ad28>] dm_suspend+0x38/0x1f0 [dm_mod]
 #1:  (&(&m->lock)->rlock){..-...}, at: [<ffffffffa077a647>] queue_if_no_path+0x27/0xc0 [dm_multipath]

stack backtrace:
CPU: 10 PID: 10364 Comm: multipathd Not tainted 3.15.0-rc4-debug+ #1
Hardware name: MSI MS-7737/Big Bang-XPower II (MS-7737), BIOS V1.5 10/16/2012
 ffffffff81fea150 ffff8807c194fa98 ffffffff814a6780 ffffffff81fea150
 ffff8807c194fad8 ffffffff814a36db ffff8807c194fb30 ffff8807c1954c88
 0000000000000001 0000000000000002 ffff8807c1954c88 ffff8807c1954440
Call Trace:
 [<ffffffff814a6780>] dump_stack+0x4e/0x7a
 [<ffffffff814a36db>] print_circular_bug+0x200/0x20f
 [<ffffffff810a4c46>] __lock_acquire+0x1716/0x1a00
 [<ffffffff810a56c3>] lock_acquire+0x93/0x1c0
 [<ffffffffa043bff3>] ? dm_table_run_md_queue_async+0x33/0x60 [dm_mod]
 [<ffffffff814aea56>] _raw_spin_lock_irqsave+0x46/0x60
 [<ffffffffa043bff3>] ? dm_table_run_md_queue_async+0x33/0x60 [dm_mod]
 [<ffffffffa043bff3>] dm_table_run_md_queue_async+0x33/0x60 [dm_mod]
 [<ffffffffa077a692>] queue_if_no_path+0x72/0xc0 [dm_multipath]
 [<ffffffffa077a6f9>] multipath_presuspend+0x19/0x20 [dm_multipath]
 [<ffffffffa043d34a>] dm_table_presuspend_targets+0x4a/0x60 [dm_mod]
 [<ffffffffa043ad5d>] dm_suspend+0x6d/0x1f0 [dm_mod]
 [<ffffffffa043ff63>] dev_suspend+0x1c3/0x220 [dm_mod]
 [<ffffffffa043fda0>] ? table_load+0x350/0x350 [dm_mod]
 [<ffffffffa0440759>] ctl_ioctl+0x269/0x500 [dm_mod]
 [<ffffffffa0440a03>] dm_ctl_ioctl+0x13/0x20 [dm_mod]
 [<ffffffff811a04c0>] do_vfs_ioctl+0x300/0x520
 [<ffffffff811ac089>] ? __fget+0x129/0x300
 [<ffffffff811abf65>] ? __fget+0x5/0x300
 [<ffffffff811ac2d0>] ? __fget_light+0x30/0x160
 [<ffffffff811a0721>] SyS_ioctl+0x41/0x80
 [<ffffffff814b84e2>] tracesys+0xd0/0xd5