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From: Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>
To: "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: v3.7: Unloading ib_ipoib triggers circular locking dependency complaint
Date: Fri, 23 Nov 2012 13:10:45 +0100	[thread overview]
Message-ID: <50AF67C5.7090200@acm.org> (raw)

Hello,

Apparently unloading the ib_ipoib kernel module triggers a circular 
locking dependency complaint. Has anyone already been looking into this ?

Thanks,

Bart.

======================================================
[ INFO: possible circular locking dependency detected ]
3.7.0-rc6-debug+ #1 Not tainted
-------------------------------------------------------
rmmod/1414 is trying to acquire lock:
  (s_active#72){++++.+}, at: [<ffffffff811baadb>] 
sysfs_addrm_finish+0x3b/0x70

but task is already holding lock:
  (rtnl_mutex){+.+.+.}, at: [<ffffffff813457a7>] rtnl_lock+0x17/0x20

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (rtnl_mutex){+.+.+.}:
        [<ffffffff8109602a>] lock_acquire+0x8a/0x120
        [<ffffffff81414cf9>] mutex_lock_nested+0x79/0x360
        [<ffffffff813457a7>] rtnl_lock+0x17/0x20
        [<ffffffffa043bb1e>] ipoib_set_mode+0xde/0xf0 [ib_ipoib]
        [<ffffffffa044253a>] set_mode+0x3a/0x90 [ib_ipoib]
        [<ffffffff812bcb28>] dev_attr_store+0x18/0x30
        [<ffffffff811b8de0>] sysfs_write_file+0xe0/0x150
        [<ffffffff8114b55b>] vfs_write+0xab/0x170
        [<ffffffff8114b885>] sys_write+0x55/0xa0
        [<ffffffff81420d42>] system_call_fastpath+0x16/0x1b

-> #0 (s_active#72){++++.+}:
        [<ffffffff8109595c>] __lock_acquire+0x1b9c/0x1c90
        [<ffffffff8109602a>] lock_acquire+0x8a/0x120
        [<ffffffff811b9ef6>] sysfs_deactivate+0x126/0x180
        [<ffffffff811baadb>] sysfs_addrm_finish+0x3b/0x70
        [<ffffffff811bb01f>] sysfs_remove_dir+0x9f/0xd0
        [<ffffffff81209136>] kobject_del+0x16/0x40
        [<ffffffff812be0dc>] device_del+0x17c/0x1c0
        [<ffffffff8134de77>] netdev_unregister_kobject+0x67/0x80
        [<ffffffff813345ba>] rollback_registered_many+0x16a/0x210
        [<ffffffff81334b71>] rollback_registered+0x31/0x40
        [<ffffffff81335138>] unregister_netdevice_queue+0x58/0xa0
        [<ffffffff81335270>] unregister_netdev+0x20/0x30
        [<ffffffffa0439ad1>] ipoib_remove_one+0xb1/0xf0 [ib_ipoib]
        [<ffffffffa033c71e>] ib_unregister_client+0x4e/0x100 [ib_core]
        [<ffffffffa0446a9d>] ipoib_cleanup_module+0x15/0x34 [ib_ipoib]
        [<ffffffff810a279b>] sys_delete_module+0x14b/0x2b0
        [<ffffffff81420d42>] system_call_fastpath+0x16/0x1b

other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(rtnl_mutex);
                                lock(s_active#72);
                                lock(rtnl_mutex);
   lock(s_active#72);

  *** DEADLOCK ***

2 locks held by rmmod/1414:
  #0:  (device_mutex){+.+.+.}, at: [<ffffffffa033c6f7>] 
ib_unregister_client+0x27/0x100 [ib_core]
  #1:  (rtnl_mutex){+.+.+.}, at: [<ffffffff813457a7>] rtnl_lock+0x17/0x20

stack backtrace:
Pid: 1414, comm: rmmod Not tainted 3.7.0-rc6-debug+ #1
Call Trace:
  [<ffffffff8140ee5c>] print_circular_bug+0x1fb/0x20c
  [<ffffffff8109595c>] __lock_acquire+0x1b9c/0x1c90
  [<ffffffff81074c85>] ? sched_clock_local+0x25/0xa0
  [<ffffffff8109602a>] lock_acquire+0x8a/0x120
  [<ffffffff811baadb>] ? sysfs_addrm_finish+0x3b/0x70
  [<ffffffff811b9ef6>] sysfs_deactivate+0x126/0x180
  [<ffffffff811baadb>] ? sysfs_addrm_finish+0x3b/0x70
  [<ffffffff81096942>] ? mark_held_locks+0xb2/0x130
  [<ffffffff811baadb>] sysfs_addrm_finish+0x3b/0x70
  [<ffffffff811bb01f>] sysfs_remove_dir+0x9f/0xd0
  [<ffffffff81209136>] kobject_del+0x16/0x40
  [<ffffffff812be0dc>] device_del+0x17c/0x1c0
  [<ffffffff8134de77>] netdev_unregister_kobject+0x67/0x80
  [<ffffffff813345ba>] rollback_registered_many+0x16a/0x210
  [<ffffffff81334b71>] rollback_registered+0x31/0x40
  [<ffffffff81335138>] unregister_netdevice_queue+0x58/0xa0
  [<ffffffff81335270>] unregister_netdev+0x20/0x30
  [<ffffffffa0439ad1>] ipoib_remove_one+0xb1/0xf0 [ib_ipoib]
  [<ffffffffa033c71e>] ib_unregister_client+0x4e/0x100 [ib_core]
  [<ffffffffa0446a9d>] ipoib_cleanup_module+0x15/0x34 [ib_ipoib]
  [<ffffffff810a279b>] sys_delete_module+0x14b/0x2b0
  [<ffffffff81212aee>] ? trace_hardirqs_on_thunk+0x3a/0x3f
  [<ffffffff81420d42>] system_call_fastpath+0x16/0x1b
--
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             reply	other threads:[~2012-11-23 12:10 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-11-23 12:10 Bart Van Assche [this message]
     [not found] ` <50AF67C5.7090200-HInyCGIudOg@public.gmane.org>
2012-11-26  8:00   ` v3.7: Unloading ib_ipoib triggers circular locking dependency complaint Or Gerlitz
     [not found]     ` <CAJZOPZJ55dqpOsnP-jbgXRrLZpyRzD2v8pg7pAAWMtWWr-m1FA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-26 10:08       ` Roland Dreier
2013-03-12 13:57       ` Bart Van Assche
     [not found]         ` <513F3455.3030309-HInyCGIudOg@public.gmane.org>
2013-03-13 15:43           ` Or Gerlitz

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