Messages in this thread | | | Date | Sat, 31 Mar 2012 20:02:46 -0700 | From | "Paul E. McKenney" <> | Subject | Re: Blocked in keyctl(...) ??? - RCU related ??? |
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On Fri, Mar 16, 2012 at 09:43:28AM +0100, Paul Rolland wrote: > Hello, > > On Mon, 12 Mar 2012 17:03:01 +0100 > Paul Rolland (ポール・ロラン) <rol@witbe.net> wrote: > > > Sometimes, my applications start "locking": nothing happens anymore, can't > > kill them... > > I manage to strace them, to find that they are executing the following > > syscall: > > > > 13686 keyctl(0x1, 0, 0xffffffffffffffff, 0x7fa90fd6a2c0, 0 > > > > and that syscall never returns. > > OK, this happened again, while running 3.3-rc7... I've used sysrq to > collect some informations and what I can see from that is the following : > > Mar 16 08:40:02 tux kernel: Call Trace: > Mar 16 08:40:02 tux kernel: [<ffffffff813b8771>] ? extract_buf+0x91/0x140 > Mar 16 08:40:02 tux kernel: [<ffffffff8166fd5a>] schedule+0x3a/0x50 > Mar 16 08:40:02 tux kernel: [<ffffffff8166e09d>] schedule_timeout+0x1ed/0x260 > Mar 16 08:40:02 tux kernel: [<ffffffff810636c1>] ? get_parent_ip+0x11/0x50 > Mar 16 08:40:02 tux kernel: [<ffffffff810636c1>] ? get_parent_ip+0x11/0x50 > Mar 16 08:40:02 tux kernel: [<ffffffff810636c1>] ? get_parent_ip+0x11/0x50 > Mar 16 08:40:02 tux kernel: [<ffffffff8166f100>] wait_for_common+0xc0/0x160 > Mar 16 08:40:02 tux kernel: [<ffffffff81062150>] ? try_to_wake_up+0x2e0/0x2e0 > Mar 16 08:40:02 tux kernel: [<ffffffff810ad020>] ? __call_rcu+0x150/0x150 > Mar 16 08:40:02 tux kernel: [<ffffffff8166f1b8>] wait_for_completion+0x18/0x20 > Mar 16 08:40:02 tux kernel: [<ffffffff81054628>] wait_rcu_gp+0x48/0x50 > Mar 16 08:40:02 tux kernel: [<ffffffff81054630>] ? wait_rcu_gp+0x50/0x50 > Mar 16 08:40:02 tux kernel: [<ffffffff810ac09c>] synchronize_rcu+0x1c/0x20 > Mar 16 08:40:02 tux kernel: [<ffffffff812ba6a9>] install_session_keyring_to_cred+0x59/0xc0 > Mar 16 08:40:02 tux kernel: [<ffffffff812bac3a>] join_session_keyring+0x12a/0x170 > Mar 16 08:40:02 tux kernel: [<ffffffff812b8cd2>] keyctl_join_session_keyring+0x32/0x60 > Mar 16 08:40:02 tux kernel: [<ffffffff812ba278>] sys_keyctl+0x168/0x180 > Mar 16 08:40:02 tux kernel: [<ffffffff81671b62>] > system_call_fastpath+0x16/0x1b > > The complete traces collected in /var/log/messages is attached to this email. > > Is there anything I can do to investigate this ?
From your message output, it looks like something is stalling RCU grace periods, possibly due to a task being preempted in an RCU read-side critical section (this assumes you are running CONFIG_PREEMPT=y).
Could you please try reproducing with CONFIG_RCU_CPU_STALL_VERBOSE=y? This would identify tasks stalling the RCU grace period.
Thanx, Paul
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