Messages in this thread Patch in this message | | | Date | Thu, 25 Feb 2016 00:07:02 -0800 | From | tip-bot for Peter Zijlstra <> | Subject | [tip:perf/urgent] perf: Fix scaling vs. perf_event_enable_on_exec() |
| |
Commit-ID: 7fce250915efca0f8f51dddee3ae89bf30d86ca5 Gitweb: http://git.kernel.org/tip/7fce250915efca0f8f51dddee3ae89bf30d86ca5 Author: Peter Zijlstra <peterz@infradead.org> AuthorDate: Wed, 24 Feb 2016 18:45:48 +0100 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Thu, 25 Feb 2016 08:43:34 +0100
perf: Fix scaling vs. perf_event_enable_on_exec()
The recent commit 3e349507d12d ("perf: Fix perf_enable_on_exec() event scheduling") caused this by moving task_ctx_sched_out() from before __perf_event_mask_enable() to after it.
The overlooked consequence of that change is that task_ctx_sched_out() would update the ctx time fields, and now __perf_event_mask_enable() uses stale time.
In order to fix this, explicitly stop our context's time before enabling the event(s).
Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dvyukov@google.com Cc: eranian@google.com Cc: panand@redhat.com Cc: sasha.levin@oracle.com Cc: vince@deater.net Fixes: 3e349507d12d ("perf: Fix perf_enable_on_exec() event scheduling") Link: http://lkml.kernel.org/r/20160224174948.159242158@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org> --- kernel/events/core.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/events/core.c b/kernel/events/core.c index 75bde93..d003088 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3143,6 +3143,7 @@ static void perf_event_enable_on_exec(int ctxn) cpuctx = __get_cpu_context(ctx); perf_ctx_lock(cpuctx, ctx); + ctx_sched_out(ctx, cpuctx, EVENT_TIME); list_for_each_entry(event, &ctx->event_list, event_entry) enabled |= event_enable_on_exec(event, ctx);
| |