From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: cgroup: INFO: suspicious RCU usage. in cgroup_name Date: Wed, 06 Mar 2013 11:02:06 -0500 Message-ID: <5137687E.50701@oracle.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Tejun Heo , Li Zefan Cc: Dave Jones , Cgroups , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" Hi all, While fuzzing with trinity inside a KVM tools guest running latest -next kernel I've stumbled on the following: [ 450.180599] =============================== [ 450.181392] [ INFO: suspicious RCU usage. ] [ 450.182101] 3.9.0-rc1-next-20130305-sasha-00048-g35e9ec5-dirty #1032 Tainted: G W [ 450.183482] ------------------------------- [ 450.184343] include/linux/cgroup.h:429 suspicious rcu_dereference_check() usage! [ 450.185575] [ 450.185575] other info that might help us debug this: [ 450.185575] [ 450.186961] [ 450.186961] rcu_scheduler_active = 1, debug_locks = 1 [ 450.188001] 4 locks held by kworker/u:0/6: [ 450.188646] #0: (khelper){.+.+.+}, at: [] process_one_work+0x238/0x570 [ 450.190186] #1: ((&sub_info->work)){+.+.+.}, at: [] process_one_work+0x238/0x570 [ 450.191824] #2: (&(&p->alloc_lock)->rlock){+.+.-.}, at: [] dump_header+0x43/0xe0 [ 450.193366] #3: (cpuset_buffer_lock){+.+...}, at: [] cpuset_print_task_mems_allowed+0x60/0x150 [ 450.195281] [ 450.195281] stack backtrace: [ 450.195987] Pid: 6, comm: kworker/u:0 Tainted: G W 3.9.0-rc1-next-20130305-sasha-00048-g35e9ec5-dirty #1032 [ 450.197678] Call Trace: [ 450.198086] [] lockdep_rcu_suspicious+0x113/0x130 [ 450.199077] [] cpuset_print_task_mems_allowed+0xe7/0x150 [ 450.200263] [] dump_header+0x7c/0xe0 [ 450.201135] [] oom_kill_process+0x82/0x370 [ 450.202048] [] out_of_memory+0x1ab/0x200 [ 450.202921] [] ? _raw_write_unlock_irq+0x50/0x80 [ 450.204068] [] __alloc_pages_slowpath+0x5bf/0x700 [ 450.205075] [] __alloc_pages_nodemask+0x2d5/0x400 [ 450.206067] [] dup_task_struct+0x68/0x1c0 [ 450.206975] [] copy_process+0xe9/0xfd0 [ 450.207798] [] ? sched_clock_local+0x25/0x90 [ 450.208679] [] ? call_helper+0x20/0x20 [ 450.209496] [] do_fork+0xbb/0x280 [ 450.210384] [] kernel_thread+0x21/0x30 [ 450.211323] [] __call_usermodehelper+0x33/0xa0 [ 450.212260] [] process_one_work+0x368/0x570 [ 450.213201] [] ? process_one_work+0x238/0x570 [ 450.214248] [] worker_thread+0x1f5/0x340 [ 450.215159] [] ? manage_workers+0x160/0x160 [ 450.216078] [] kthread+0xe2/0xf0 [ 450.216901] [] ? __lock_release+0x1da/0x1f0 [ 450.217824] [] ? __init_kthread_worker+0x70/0x70 [ 450.218791] [] ret_from_fork+0x7c/0xb0 [ 450.219627] [] ? __init_kthread_worker+0x70/0x70 [ 450.220780] kworker/u:0 cpuset=/ mems_allowed=0 The offending commit looks like "cgroup: fix cgroup_path() vs rename() race". Thanks, Sasha