From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755407Ab1LZMQt (ORCPT ); Mon, 26 Dec 2011 07:16:49 -0500 Received: from mail-ee0-f46.google.com ([74.125.83.46]:35231 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755369Ab1LZMQr (ORCPT ); Mon, 26 Dec 2011 07:16:47 -0500 Message-ID: <1324901803.31721.4.camel@lappy> Subject: INFO: task rcuc/0:7 blocked for more than 120 seconds. From: Sasha Levin To: "Paul E. McKenney" Cc: linux-kernel Date: Mon, 26 Dec 2011 14:16:43 +0200 Content-Type: text/plain; charset="us-ascii" X-Mailer: Evolution 3.2.2 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Paul, I've recently got the following panic which was caused by khungtask: [ 1921.589512] INFO: task rcuc/0:7 blocked for more than 120 seconds. [ 1921.590370] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1921.597103] rcuc/0 D ffff880012f61630 4400 7 2 0x00000000 [ 1921.598646] ffff880012f6b980 0000000000000086 ffff880012f6bfd8 00000000001d4740 [ 1921.600289] ffff880012f6bfd8 ffff880012f61630 ffff880012f6bfd8 ffff880012f6a000 [ 1921.601707] 00000000001d4800 ffff880012f6a000 ffff880012f6bfd8 00000000001d4800 [ 1921.603258] Call Trace: [ 1921.603703] [] schedule+0x3a/0x50 [ 1921.605462] [] schedule_timeout+0x255/0x4d0 [ 1921.606540] [] ? mark_held_locks+0x6e/0x130 [ 1921.607633] [] ? lock_release_holdtime+0xb2/0x160 [ 1921.608798] [] ? _raw_spin_unlock_irq+0x2b/0x70 [ 1921.610154] [] wait_for_common+0x120/0x170 [ 1921.617878] [] ? try_to_wake_up+0x2f0/0x2f0 [ 1921.618949] [] ? __call_rcu+0x3c0/0x3c0 [ 1921.621405] [] wait_for_completion+0x18/0x20 [ 1921.623622] [] wait_rcu_gp+0x59/0x80 [ 1921.626789] [] ? perf_trace_rcu_batch_end+0x120/0x120 [ 1921.629440] [] ? wait_for_common+0x44/0x170 [ 1921.632445] [] synchronize_rcu+0x1c/0x20 [ 1921.635455] [] atomic_notifier_chain_unregister+0x60/0x80 [ 1921.638550] [] task_handoff_unregister+0x13/0x20 [ 1921.641271] [] task_notify_func+0x2f/0x40 [ 1921.643894] [] notifier_call_chain+0x67/0x110 [ 1921.646580] [] __atomic_notifier_call_chain+0x74/0x110 [ 1921.654064] [] ? __atomic_notifier_call_chain+0x39/0x110 [ 1921.656034] [] ? __put_task_struct+0xc0/0x120 [ 1921.658625] [] ? will_become_orphaned_pgrp+0x100/0x100 [ 1921.661527] [] atomic_notifier_call_chain+0x11/0x20 [ 1921.664295] [] profile_handoff_task+0x15/0x20 [ 1921.666885] [] __put_task_struct+0x7b/0x120 [ 1921.669492] [] delayed_put_task_struct+0x35/0x140 [ 1921.672129] [] rcu_do_batch.clone.12+0x224/0xab0 [ 1921.674697] [] ? __schedule+0x432/0x890 [ 1921.677028] [] rcu_cpu_kthread+0x48a/0xa40 [ 1921.682719] [] ? _raw_spin_unlock_irqrestore+0x55/0xa0 [ 1921.684913] [] ? rcu_idle_enter+0xb0/0xb0 [ 1921.686641] [] kthread+0xb6/0xc0 [ 1921.689956] [] kernel_thread_helper+0x4/0x10 [ 1921.692815] [] ? finish_task_switch+0x80/0x110 [ 1921.695613] [] ? retint_restore_args+0x13/0x13 [ 1921.698409] [] ? kthread_flush_work_fn+0x10/0x10 [ 1921.701199] [] ? gs_change+0x13/0x13 [ 1921.703680] 1 lock held by rcuc/0/7: [ 1921.705325] #0: (rcu_read_lock){.+.+..}, at: [] __atomic_notifier_call_chain+0x39/0x110 [ 1921.710297] Kernel panic - not syncing: hung_task: blocked tasks [ 1921.715383] Rebooting in 1 seconds.. This is the RCU related .config: # cat .config | grep RCU # RCU Subsystem CONFIG_TREE_PREEMPT_RCU=y CONFIG_PREEMPT_RCU=y CONFIG_RCU_TRACE=y CONFIG_RCU_FANOUT=64 # CONFIG_RCU_FANOUT_EXACT is not set CONFIG_RCU_FAST_NO_HZ=y CONFIG_TREE_RCU_TRACE=y CONFIG_RCU_BOOST=y CONFIG_RCU_BOOST_PRIO=1 CONFIG_RCU_BOOST_DELAY=500 CONFIG_DEBUG_OBJECTS_RCU_HEAD=y CONFIG_PROVE_RCU=y CONFIG_PROVE_RCU_REPEATEDLY=y CONFIG_SPARSE_RCU_POINTER=y # CONFIG_RCU_TORTURE_TEST is not set CONFIG_RCU_CPU_STALL_TIMEOUT=60 CONFIG_RCU_CPU_STALL_VERBOSE=y Please let me know if I can help with anything else. -- Sasha.