[BUG -rt] circular locking deadlock

[john stultz <johnstul@us.ibm.com>]

Hey Ingo, Thomas,

I was playing with the latency tracer on 2.6.23-rc2-rt2 while a "make
-j8" was going on in the background and the box hung with this on the
console:


============================================
[ BUG: circular locking deadlock detected! ]
--------------------------------------------
cc1/7161 is deadlocking current task cc1/7164


1) cc1/7164 is trying to acquire this lock:
 [ffff8101fa375250] {&list->lock}
.. ->owner: ffff8101ef7f7162
.. held by:               cc1: 7161 [ffff8101ef7f7160, 120]

2) cc1/7161 is blocked on this lock:
 [ffff8102118e5900] {&list->lock}
.. ->owner: ffff8100ddb3ace2
.. held by:               cc1: 7164 [ffff8100ddb3ace0, 120]

cc1/7161's [blocked] stackdump:

 ffff8101f9423c68 0000000000000086 0000000100000000 0000000000000002
 ffffffff82205d00 0000000000000202 ffffffff82189280 ffff8101ef7f7160
 ffff8100ddb3ace0 ffff8101f9423c10 0000000000000202 0000000000000000
Call Trace:
 [<ffffffff8100c58c>] mcount+0x2c/0x3a
 [<ffffffff817e6e6b>] schedule+0x3b/0x130
 [<ffffffff817e7feb>] rt_spin_lock_slowlock+0xdb/0x210
 [<ffffffff817e8b4d>] __rt_spin_lock+0x3d/0x50
 [<ffffffff817e8b6e>] rt_spin_lock+0xe/0x10
 [<ffffffff81297a62>] __lock_list+0x42/0x70
 [<ffffffff81297b43>] lock_list_splice_init+0x33/0xb0
 [<ffffffff810bf9d8>] file_move+0xc8/0xd0
 [<ffffffff810bc99e>] __dentry_open+0xae/0x1d0
 [<ffffffff810bcb84>] nameidata_to_filp+0x44/0x60
 [<ffffffff810bcbed>] do_filp_open+0x4d/0x60
 [<ffffffff817e8ace>] __lock_text_start+0xe/0x10
 [<ffffffff810bc8a3>] get_unused_fd_flags+0x103/0x130
 [<ffffffff810bcc61>] do_sys_open+0x61/0x100
 [<ffffffff810bcd40>] sys_open+0x20/0x30
 [<ffffffff8100c9a5>] tracesys+0x151/0x1be

---------------------------
| preempt count: 00000002 ]
| 2-level deep critical section nesting:
----------------------------------------
.. [<ffffffff817e5e33>] .... __schedule+0x23/0x265
.....[<ffffffff817e6e6b>] ..   ( <= schedule+0x3b/0x130)
.. [<ffffffff817e9041>] .... __spin_lock_irq+0x21/0x40
.....[<ffffffff817e5ec4>] ..   ( <= __schedule+0xb4/0x265)


cc1/7164's [current] stackdump:


Call Trace:
 [<ffffffff8100e433>] show_stack+0x13/0x20
 [<ffffffff8106c643>] debug_rt_mutex_print_deadlock+0x163/0x180
 [<ffffffff817e7fe6>] rt_spin_lock_slowlock+0xd6/0x210
 [<ffffffff817e8b4d>] __rt_spin_lock+0x3d/0x50
 [<ffffffff817e8b6e>] rt_spin_lock+0xe/0x10
 [<ffffffff81297a62>] __lock_list+0x42/0x70
 [<ffffffff81297be6>] lock_list_del_init+0x26/0x70
 [<ffffffff810bf8fa>] file_kill+0x4a/0x60
 [<ffffffff810bfb8e>] __fput+0x12e/0x1d0
 [<ffffffff810bfcc5>] fput+0x25/0x30
 [<ffffffff810bc771>] filp_close+0x61/0x90
 [<ffffffff810bded9>] sys_close+0xa9/0x100
 [<ffffffff8100c9a5>] tracesys+0x151/0x1be

---------------------------
| preempt count: 00000000 ]
| 0-level deep critical section nesting:
----------------------------------------

[ turning off deadlock detection.Please report this trace. ]


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