From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753893Ab3D3GbK (ORCPT ); Tue, 30 Apr 2013 02:31:10 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52713 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752731Ab3D3GbG (ORCPT ); Tue, 30 Apr 2013 02:31:06 -0400 Date: Mon, 29 Apr 2013 23:30:30 -0700 From: tip-bot for Li Zhong Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, zhong@linux.vnet.ibm.com, paulmck@linux.vnet.ibm.com, fweisbec@gmail.com, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, zhong@linux.vnet.ibm.com, paulmck@linux.vnet.ibm.com, fweisbec@gmail.com, tglx@linutronix.de In-Reply-To: <1367119558.6391.34.camel@ThinkPad-T5421.cn.ibm.com> References: <1367119558.6391.34.camel@ThinkPad-T5421.cn.ibm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/nohz] nohz: Protect smp_processor_id() in tick_nohz_task_switch() Git-Commit-ID: 6296ace467c8640317414ba589b124323806f7ce X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 6296ace467c8640317414ba589b124323806f7ce Gitweb: http://git.kernel.org/tip/6296ace467c8640317414ba589b124323806f7ce Author: Li Zhong AuthorDate: Sun, 28 Apr 2013 11:25:58 +0800 Committer: Ingo Molnar CommitDate: Mon, 29 Apr 2013 13:17:33 +0200 nohz: Protect smp_processor_id() in tick_nohz_task_switch() I saw following error when testing the latest nohz code on Power: [ 85.295384] BUG: using smp_processor_id() in preemptible [00000000] code: rsyslogd/3493 [ 85.295396] caller is .tick_nohz_task_switch+0x1c/0xb8 [ 85.295402] Call Trace: [ 85.295408] [c0000001fababab0] [c000000000012dc4] .show_stack+0x110/0x25c (unreliable) [ 85.295420] [c0000001fababba0] [c0000000007c4b54] .dump_stack+0x20/0x30 [ 85.295430] [c0000001fababc10] [c00000000044eb74] .debug_smp_processor_id+0xf4/0x124 [ 85.295438] [c0000001fababca0] [c0000000000d7594] .tick_nohz_task_switch+0x1c/0xb8 [ 85.295447] [c0000001fababd20] [c0000000000b9748] .finish_task_switch+0x13c/0x160 [ 85.295455] [c0000001fababdb0] [c0000000000bbe50] .schedule_tail+0x50/0x124 [ 85.295463] [c0000001fababe30] [c000000000009dc8] .ret_from_fork+0x4/0x54 The code below moves the test into local_irq_save/restore section to avoid the above complaint. Signed-off-by: Li Zhong Acked-by: Frederic Weisbecker Cc: Peter Zijlstra Cc: Paul McKenney Link: http://lkml.kernel.org/r/1367119558.6391.34.camel@ThinkPad-T5421.cn.ibm.com Signed-off-by: Ingo Molnar --- kernel/time/tick-sched.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index da53c8f..1c9f53b 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -251,14 +251,15 @@ void tick_nohz_task_switch(struct task_struct *tsk) { unsigned long flags; - if (!tick_nohz_full_cpu(smp_processor_id())) - return; - local_irq_save(flags); + if (!tick_nohz_full_cpu(smp_processor_id())) + goto out; + if (tick_nohz_tick_stopped() && !can_stop_full_tick()) tick_nohz_full_kick(); +out: local_irq_restore(flags); }