Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755178AbaJ2FIh (ORCPT ); Wed, 29 Oct 2014 01:08:37 -0400 Received: from relay.parallels.com ([195.214.232.42]:60587 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751631AbaJ2FIf (ORCPT ); Wed, 29 Oct 2014 01:08:35 -0400 Message-ID: <1414559311.8574.14.camel@tkhai> Subject: Re: [sched] [ INFO: suspicious RCU usage. ] From: Kirill Tkhai To: Fengguang Wu CC: Peter Zijlstra , LKP , Date: Wed, 29 Oct 2014 08:08:31 +0300 In-Reply-To: <20141028142715.GB19097@wfg-t540p.sh.intel.com> References: <20141028142715.GB19097@wfg-t540p.sh.intel.com> Organization: Parallels Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.8.5-2+b3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Originating-IP: [10.30.26.172] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks, Fengguang. I've suggested this patch https://lkml.org/lkml/2014/10/28/41. В Вт, 28/10/2014 в 22:27 +0800, Fengguang Wu пишет: > Greetings, > > 0day kernel testing robot got the below dmesg and the first bad commit is > > git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/urgent > commit f6a2b544517d33f6a1e428567bda96fd859ce1c9 > Author: Kirill Tkhai > AuthorDate: Mon Oct 27 14:18:25 2014 +0400 > Commit: Peter Zijlstra > CommitDate: Mon Oct 27 13:23:31 2014 +0100 > > sched: Fix race between task_group and sched_task_group > > The race may happen when somebody is changing task_group of a forking task. > Child's cgroup is the same as parent's after dup_task_struct() (there just > memory copying). Also, cfs_rq and rt_rq are the same as parent's. > > But if parent changes its task_group before it's called cgroup_post_fork(), > we do not reflect this situation on child. Child's cfs_rq and rt_rq remain > the same, while child's task_group changes in cgroup_post_fork(). > > To fix this we introduce fork() method, which calls sched_move_task() directly. > This function changes sched_task_group on appropriate (also its logic has > no problem with freshly created tasks, so we shouldn't introduce something > special; we are able just to use it). > > Possibly, this decides the Burke Libbey's problem: https://lkml.org/lkml/2014/10/24/456 > > Signed-off-by: Kirill Tkhai > Signed-off-by: Peter Zijlstra (Intel) > Link: http://lkml.kernel.org/r/1414405105.19914.169.camel@tkhai > > +---------------------------+-----------+------------+------------+ > | | v3.18-rc2 | f6a2b54451 | 8e5859c73b | > +---------------------------+-----------+------------+------------+ > | boot_successes | 200 | 0 | 0 | > | boot_failures | 1 | 20 | 11 | > | BUG:kernel_boot_hang | 1 | | | > | INFO:suspicious_RCU_usage | 0 | 20 | 11 | > | backtrace:do_fork | 0 | 20 | 11 | > +---------------------------+-----------+------------+------------+ > > [ 0.060187] > [ 0.060500] =============================== > [ 0.060500] =============================== > [ 0.061307] [ INFO: suspicious RCU usage. ] > [ 0.061307] [ INFO: suspicious RCU usage. ] > [ 0.062109] 3.18.0-rc2-gf6a2b54 #404 Not tainted > [ 0.062109] 3.18.0-rc2-gf6a2b54 #404 Not tainted > [ 0.063049] ------------------------------- > > git bisect start 8e5859c73b9f45602222441a23eba899bb24c82e 522e980064c24d3dd9859e9375e17417496567cf -- > git bisect bad 259820751fd17a4b49098429c68c2c0adfd1c9ed # 21:11 0- 2 Merge branch 'sched/core' > git bisect bad 8c64bf8de891aa51e916b51a3f7992321ec19b63 # 21:15 0- 1 Merge branch 'sched/urgent' > git bisect bad fd457f2bafdc4e367d1814ac395035a35980783f # 21:27 0- 7 sched/fair: Care divide error in update_task_scan_period() > git bisect bad fb5b330f079e243dcc831e9a3d65b9b9fbbed7f8 # 21:36 0- 1 sched/deadline: don't replenish from a !SCHED_DEADLINE entity > git bisect bad f6a2b544517d33f6a1e428567bda96fd859ce1c9 # 21:41 0- 2 sched: Fix race between task_group and sched_task_group > # first bad commit: [f6a2b544517d33f6a1e428567bda96fd859ce1c9] sched: Fix race between task_group and sched_task_group > git bisect good cac7f2429872d3733dc3f9915857b1691da2eb2f # 21:58 60+ 1 Linux 3.18-rc2 > git bisect bad 8e5859c73b9f45602222441a23eba899bb24c82e # 22:00 0- 11 Merge branch 'sched/wait' > git bisect good cac7f2429872d3733dc3f9915857b1691da2eb2f # 22:05 60+ 1 Linux 3.18-rc2 > git bisect good 7a891e6323e963f3301e44bdeee734028e34d390 # 22:14 60+ 0 Add linux-next specific files for 20141027 > > > This script may reproduce the error. > > ---------------------------------------------------------------------------- > #!/bin/bash > > kernel=$1 > initrd=quantal-core-x86_64.cgz > > wget --no-clobber https://github.com/fengguang/reproduce-kernel-bug/raw/master/initrd/$initrd > > kvm=( > qemu-system-x86_64 > -cpu kvm64 > -enable-kvm > -kernel $kernel > -initrd $initrd > -m 320 > -smp 2 > -net nic,vlan=1,model=e1000 > -net user,vlan=1 > -boot order=nc > -no-reboot > -watchdog i6300esb > -rtc base=localtime > -serial stdio > -display none > -monitor null > ) > > append=( > hung_task_panic=1 > earlyprintk=ttyS0,115200 > debug > apic=debug > sysrq_always_enabled > rcupdate.rcu_cpu_stall_timeout=100 > panic=-1 > softlockup_panic=1 > nmi_watchdog=panic > oops=panic > load_ramdisk=2 > prompt_ramdisk=0 > console=ttyS0,115200 > console=tty0 > vga=normal > root=/dev/ram0 > rw > drbd.minor_count=8 > ) > > "${kvm[@]}" --append "${append[*]}" > ---------------------------------------------------------------------------- > > Thanks, > Fengguang > _______________________________________________ > LKP mailing list > LKP@linux.intel.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/