From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Subject: Re: [PATCH v5 00/45] CPU hotplug: stop_machine()-free CPU hotplug Date: Mon, 18 Feb 2013 16:27:32 +0530 Message-ID: <5122091C.2080308@linux.vnet.ibm.com> References: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> <510FBC01.2030405@linux.vnet.ibm.com> <87haloiwv0.fsf@rustcorp.com.au> <51134596.4080106@linux.vnet.ibm.com> <20130208154113.GV17833@n2100.arm.linux.org.uk> <51152B81.2050501@linux.vnet.ibm.com> <51153F72.1060005@linux.vnet.ibm.com> <5118E2CD.90401@linux.vnet.ibm.com> <20130211190852.GA5695@linux.vnet.ibm.com> <5119BDFD.1000909@linux.vnet.ibm.com> <511E8F3C.2010406@linux.vnet.ibm.com> <512203B3.7090002@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-arch-owner@vger.kernel.org To: Thomas Gleixner Cc: Vincent Guittot , paulmck@linux.vnet.ibm.com, Russell King - ARM Linux , linux-doc@vger.kernel.org, peterz@infradead.org, fweisbec@gmail.com, linux-kernel@vger.kernel.org, walken@google.com, mingo@kernel.org, linux-arch@vger.kernel.org, xiaoguangrong@linux.vnet.ibm.com, wangyun@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, Rusty Russell , rostedt@goodmis.org, rjw@sisk.pl, namhyung@kernel.org, linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org, oleg@redhat.com, sbw@mit.edu, tj@kernel.org, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org List-Id: linux-pm@vger.kernel.org On 02/18/2013 04:24 PM, Thomas Gleixner wrote: > On Mon, 18 Feb 2013, Srivatsa S. Bhat wrote: >> Lockup observed while running this patchset, with CPU_IDLE and INTEL_IDLE turned >> on in the .config: >> >> smpboot: CPU 1 is now offline >> Kernel panic - not syncing: Watchdog detected hard LOCKUP on cpu 11 >> Pid: 0, comm: swapper/11 Not tainted 3.8.0-rc7+stpmch13-1 #8 >> Call Trace: >> [] do_raw_spin_lock+0x7e/0x150 >> [] _raw_spin_lock_irqsave+0x61/0x70 >> [] ? clockevents_notify+0x28/0x150 >> [] ? _raw_spin_unlock_irqrestore+0x77/0x80 >> [] clockevents_notify+0x28/0x150 >> [] intel_idle+0xaf/0xe0 >> [] ? disable_cpuidle+0x20/0x20 >> [] cpuidle_enter+0x19/0x20 >> [] cpuidle_wrap_enter+0x41/0xa0 >> [] cpuidle_enter_tk+0x10/0x20 >> [] cpuidle_enter_state+0x17/0x50 >> [] cpuidle_idle_call+0xd9/0x290 >> [] cpu_idle+0xe5/0x140 >> [] start_secondary+0xdd/0xdf > >> BUG: spinlock lockup suspected on CPU#2, migration/2/19 >> lock: clockevents_lock+0x0/0x40, .magic: dead4ead, .owner: swapper/8/0, .owner_cpu: 8 > > Unfortunately there is no back trace for cpu8. Yes :-( I had run this several times hoping to get a backtrace on the lock-holder, expecting trigger_all_cpu_backtrace() to get it right at least once. But I hadn't succeeded even once. > That's probably caused > by the watchdog -> panic setting. > Oh, ok.. > So we have no idea why cpu2 and 11 get stuck on the clockevents_lock > and without that information it's impossible to decode. > But thankfully, the issue seems to have been resolved by the diff I posted in my previous mail, along with the fixes related to memory barriers. Regards, Srivatsa S. Bhat