Re: lockdep: strange %s#5 lock name
From: Tejun Heo
Date: Thu Feb 13 2014 - 16:26:57 EST
On Thu, Feb 13, 2014 at 12:35:24PM +0800, Li Zhong wrote:
> [ 5.251993] ------------[ cut here ]------------
> [ 5.252019] WARNING: CPU: 0 PID: 221 at kernel/locking/lockdep.c:710 __lock_acquire+0x1761/0x1f60()
> [ 5.252019] Modules linked in: e1000
> [ 5.252019] CPU: 0 PID: 221 Comm: lvm Not tainted 3.14.0-rc2-next-20140212 #1
> [ 5.252019] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007
> [ 5.252019] 0000000000000009 ffff880118e91938 ffffffff8155fe12 ffff880118e91978
> [ 5.252019] ffffffff8105c195 ffff880118e91958 ffffffff81eb33d0 0000000000000002
> [ 5.252019] ffff880118dd2318 0000000000000000 0000000000000000 ffff880118e91988
> [ 5.252019] Call Trace:
> [ 5.252019] [<ffffffff8155fe12>] dump_stack+0x19/0x1b
> [ 5.252019] [<ffffffff8105c195>] warn_slowpath_common+0x85/0xb0
> [ 5.252019] [<ffffffff8105c1da>] warn_slowpath_null+0x1a/0x20
> [ 5.252019] [<ffffffff810a1721>] __lock_acquire+0x1761/0x1f60
> [ 5.252019] [<ffffffff8109ec2e>] ? mark_held_locks+0xae/0x120
> [ 5.252019] [<ffffffff8109ef4e>] ? debug_check_no_locks_freed+0x8e/0x160
> [ 5.252019] [<ffffffff810a264c>] ? lockdep_init_map+0xac/0x600
> [ 5.252019] [<ffffffff810a251a>] lock_acquire+0x9a/0x120
> [ 5.252019] [<ffffffff810793f5>] ? flush_workqueue+0x5/0x750
> [ 5.252019] [<ffffffff810794f9>] flush_workqueue+0x109/0x750
> [ 5.252019] [<ffffffff810793f5>] ? flush_workqueue+0x5/0x750
> [ 5.252019] [<ffffffff81566890>] ? _raw_spin_unlock_irq+0x30/0x40
> [ 5.252019] [<ffffffff810b7720>] ? srcu_reschedule+0xe0/0xf0
> [ 5.252019] [<ffffffff81405889>] dm_suspend+0xe9/0x1e0
> [ 5.252019] [<ffffffff8140a853>] dev_suspend+0x1e3/0x270
> [ 5.252019] [<ffffffff8140a670>] ? table_load+0x350/0x350
> [ 5.252019] [<ffffffff8140b40c>] ctl_ioctl+0x26c/0x510
> [ 5.252019] [<ffffffff810a03dc>] ? __lock_acquire+0x41c/0x1f60
> [ 5.252019] [<ffffffff810923d8>] ? vtime_account_user+0x98/0xb0
> [ 5.252019] [<ffffffff8140b6c3>] dm_ctl_ioctl+0x13/0x20
> [ 5.252019] [<ffffffff811986c8>] do_vfs_ioctl+0x88/0x570
> [ 5.252019] [<ffffffff811a5579>] ? __fget_light+0x129/0x150
> [ 5.252019] [<ffffffff81198c41>] SyS_ioctl+0x91/0xb0
> [ 5.252019] [<ffffffff8157049d>] tracesys+0xcf/0xd4
> [ 5.252019] ---[ end trace ff1fa506f34be3bc ]---
>
> It seems to me that when the second time alloc_workqueue() is called
> from the same code path, it would have two locks with the same key, but
> not the same &wq->name, which doesn't meet lockdep's assumption.
Dang... I reverted the previous patch for now. Peter, does this
approach sound good to you?
Thanks.
--
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/