Messages in this thread | | | Date | Mon, 3 Oct 2011 18:53:22 +0100 | From | Sitsofe Wheeler <> | Subject | lockdep recursive locking detected (rcu_kthread / __cache_free) |
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Hi,
While running 3.1.0-rc8 the following lockdep warning (seemingly related to RCU) was printed as the kernel was starting.
udev: starting version 151 udevd (263): /proc/263/oom_adj is deprecated, please use /proc/263/oom_score_adj instead.
============================================= [ INFO: possible recursive locking detected ] 3.1.0-rc8-dirty #508 --------------------------------------------- rcu_kthread/6 is trying to acquire lock: (&(&parent->list_lock)->rlock){..-...}, at: [<b016fe11>] __cache_free+0x2dd/0x382
but task is already holding lock: (&(&parent->list_lock)->rlock){..-...}, at: [<b016fe11>] __cache_free+0x2dd/0x382
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(&(&parent->list_lock)->rlock); lock(&(&parent->list_lock)->rlock);
*** DEADLOCK ***
May be due to missing lock nesting notation
1 lock held by rcu_kthread/6: #0: (&(&parent->list_lock)->rlock){..-...}, at: [<b016fe11>] __cache_free+0x2dd/0x382
stack backtrace: Pid: 6, comm: rcu_kthread Not tainted 3.1.0-rc8-dirty #508 Call Trace: [<b0144466>] __lock_acquire+0xb90/0xc0e [<b044c0c2>] ? _raw_spin_unlock_irqrestore+0x2f/0x46 [<b0223ebc>] ? debug_object_active_state+0x94/0xbc [<b01315af>] ? rcuhead_fixup_activate+0x26/0x4c [<b01448be>] lock_acquire+0x5b/0x72 [<b016fe11>] ? __cache_free+0x2dd/0x382 [<b044bb22>] _raw_spin_lock+0x25/0x34 [<b016fe11>] ? __cache_free+0x2dd/0x382 [<b016fe11>] __cache_free+0x2dd/0x382 [<b016ff5c>] kmem_cache_free+0x3e/0x5b [<b0170097>] slab_destroy+0x11e/0x126 [<b0170184>] free_block+0xe5/0x112 [<b016fe54>] __cache_free+0x320/0x382 [<b01759a1>] ? file_free_rcu+0x32/0x39 [<b016ff5c>] kmem_cache_free+0x3e/0x5b [<b01759a1>] file_free_rcu+0x32/0x39 [<b014ca68>] rcu_process_callbacks+0x95/0xa8 [<b014cb34>] rcu_kthread+0xb9/0xd2 [<b013356c>] ? wake_up_bit+0x1b/0x1b [<b014ca7b>] ? rcu_process_callbacks+0xa8/0xa8 [<b0133305>] kthread+0x6c/0x71 [<b0133299>] ? __init_kthread_worker+0x42/0x42 [<b044ce02>] kernel_thread_helper+0x6/0xd
-- Sitsofe | http://sucs.org/~sits/
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