BUG: bad unlock balance detected! (__sigqueue_alloc)

BUG: bad unlock balance detected! (__sigqueue_alloc)

[Axel Lin]

Hi,
I got below hangup with current Linus' tree.

[  166.378906] ------------[ cut here ]------------
[  166.385742] WARNING: CPU: 0 PID: 0 at kernel/rcu/update.c:107 __rcu_read_unlock+0x70/0x84()
[  166.394531] CPU: 0 PID: 0 Comm:  Not tainted 3.13.0-rc4-00291-g002c96b-dirty #2135
[  166.404296] [<0000c4f0>] (unwind_backtrace+0x0/0xe0) from [<0000ae98>] (show_stack+0x10/0x14)
[  166.415039] [<0000ae98>] (show_stack+0x10/0x14) from [<0000f924>] (warn_slowpath_common+0x58/0x78)
[  166.425781] [<0000f924>] (warn_slowpath_common+0x58/0x78) from [<0000f9e8>] (warn_slowpath_null+0x18/0x1c)
[  166.437499] [<0000f9e8>] (warn_slowpath_null+0x18/0x1c) from [<00041004>] (__rcu_read_unlock+0x70/0x84)
[  166.449218] [<00041004>] (__rcu_read_unlock+0x70/0x84) from [<000185a4>] (__sigqueue_alloc+0x98/0x180)
[  166.459960] [<000185a4>] (__sigqueue_alloc+0x98/0x180) from [<00000000>] (  (null))
[  166.467773] ---[ end trace 97ba89e778f73a83 ]---
[  166.475585]
[  166.477539] =====================================
[  166.482421] [ BUG: bad unlock balance detected! ]
[  166.487304] 3.13.0-rc4-00291-g002c96b-dirty #2135 Tainted: G        W
[  166.495117] -------------------------------------
[  166.499999] kworker/0:0/4 is trying to release lock (rcu_read_lock) at:
[  166.507812] [<0001850c>] __sigqueue_alloc+0x0/0x180
[  166.512695] but there are no more locks to release!
[  166.518554]
[  166.518554] other info that might help us debug this:
[  166.525390] 2 locks held by kworker/0:0/4:
[  166.530273]  #0:  (%s%d){.+.+.+}, at: [<00020df4>] process_one_work+0x1f0/0x420
[  166.539062]  #1:  ((&new->work)){+.+.+.}, at: [<00020df4>] process_one_work+0x1f0/0x420
[  166.547851]
[  166.547851] stack backtrace:
[  166.553710] CPU: 0 PID: 4 Comm: kworker/0:0 Tainted: G        W    3.13.0-rc4-00291-g002c96b-dirty #2135
[  166.564453] Workqueue: mtdblock1 mtd_blktrans_work
[  166.571289] [<0000c4f0>] (unwind_backtrace+0x0/0xe0) from [<0000ae98>] (show_stack+0x10/0x14)
[  166.582031] [<0000ae98>] (show_stack+0x10/0x14) from [<0003224c>] (print_unlock_imbalance_bug+0xa4/0xd8)
[  166.593749] [<0003224c>] (print_unlock_imbalance_bug+0xa4/0xd8) from [<00036fc4>] (lock_release+0x1ac/0x200)
[  166.605468] [<00036fc4>] (lock_release+0x1ac/0x200) from [<000185a0>] (__sigqueue_alloc+0x94/0x180)
[  166.616210] [<000185a0>] (__sigqueue_alloc+0x94/0x180) from [<01e16940>] (0x1e16940)