On Thu, Dec 10, 2015 at 08:57:40PM +0100, Peter Zijlstra wrote:
> I'm not sure I can explain your problem with this, but I figure its
> worth a try.
Did it make a difference?
Also, does the syzkaller thing do cpu-hotplug during its runs?
> ---
> kernel/events/core.c | 15 +++++----------
> 1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index c3d61b92d805..d5293325d8c5 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -3136,15 +3136,16 @@ static int event_enable_on_exec(struct perf_event
> *event,
> * Enable all of a task's events that have been marked enable-on-exec.
> * This expects task == current.
> */
> -static void perf_event_enable_on_exec(struct perf_event_context *ctx)
> +static void perf_event_enable_on_exec(int ctxn)
> {
> - struct perf_event_context *clone_ctx = NULL;
> + struct perf_event_context *ctx, *clone_ctx = NULL;
> struct perf_event *event;
> unsigned long flags;
> int enabled = 0;
> int ret;
>
> local_irq_save(flags);
> + ctx = current->perf_event_ctxp[ctxn];
> if (!ctx || !ctx->nr_events)
> goto out;
>
> @@ -3187,17 +3188,11 @@ static void perf_event_enable_on_exec(struct
> perf_event_context *ctx)
>
> void perf_event_exec(void)
> {
> - struct perf_event_context *ctx;
> int ctxn;
>
> rcu_read_lock();
> - for_each_task_context_nr(ctxn) {
> - ctx = current->perf_event_ctxp[ctxn];
> - if (!ctx)
> - continue;
> -
> - perf_event_enable_on_exec(ctx);
> - }
> + for_each_task_context_nr(ctxn)
> + perf_event_enable_on_exec(ctxn);
> rcu_read_unlock();
> }
>
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