* tip-bot for Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
> Commit-ID: 856d56b9e5de650a64a6c41c17aaed702b55d578
> Gitweb: http://git.kernel.org/tip/856d56b9e5de650a64a6c41c17aaed702b55d578
> Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> AuthorDate: Fri, 15 May 2009 20:45:59 +0200
> Committer: Ingo Molnar <mingo@xxxxxxx>
> CommitDate: Sun, 17 May 2009 07:52:24 +0200
>
> perf_counter: Fix counter inheritance
>
> Srivatsa Vaddagiri reported that a Java workload triggers this
> warning in kernel/exit.c:
>
> WARN_ON_ONCE(!list_empty(&tsk->perf_counter_ctx.counter_list));
>
> Add the inherited counter propagation on self-detach, this could
> cause counter leaks and incomplete stats in threaded code like
> the below:
>
> #include <pthread.h>
> #include <unistd.h>
>
> void *thread(void *arg)
> {
> sleep(5);
> return NULL;
> }
>
> void main(void)
> {
> pthread_t thr;
> pthread_create(&thr, NULL, thread, NULL);
> }
>
> Reported-by: Srivatsa Vaddagiri <vatsa@xxxxxxxxxx>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Cc: Paul Mackerras <paulus@xxxxxxxxx>
> Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
>
>
> ---
> kernel/exit.c | 6 ++++++
> 1 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/exit.c b/kernel/exit.c
> index 4741376..16d74f1 100644
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -128,6 +128,12 @@ static void __exit_signal(struct task_struct *tsk)
> sig = NULL; /* Marker for below. */
> }
>
> + /*
> + * Flush inherited counters to the parent - before the parent
> + * gets woken up by child-exit notifications.
> + */
> + perf_counter_exit_task(tsk);
Causes:
[ 447.882292] BUG: sleeping function called from invalid context at kernel/mutex.c:94
[ 447.890094] in_atomic(): 0, irqs_disabled(): 1, pid: 23597, name: hackbench_pth
[ 447.897587] Pid: 23597, comm: hackbench_pth Not tainted 2.6.30-rc6-tip #188
[ 447.904678] Call Trace:
[ 447.907158] [<ffffffff814cdd0b>] ? mutex_lock+0x15/0x37
[ 447.912518] [<ffffffff8108f1e3>] ? perf_counter_exit_task+0x170/0x1e9
[ 447.919134] [<ffffffff81046182>] ? release_task+0x22c/0x402
[ 447.924859] [<ffffffff8104789d>] ? do_exit+0x655/0x6e7
[ 447.930144] [<ffffffff810479ea>] ? complete_and_exit+0x0/0x16
[ 447.936054] [<ffffffff8100baab>] ? system_call_fastpath+0x16/0x1b
when running:
perf stat ./hackbench_pth 20
release_task() is a deep-atomic context, we cannot acquire a mutex
there. I'm not sure we can change that lock to a spinlock straight
away.
Ingo
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