From: Peter Zijlstra <peterz@infradead.org> Date: Wed, 24 Feb 2016 17:45:48 +0000 (+0100) Subject: perf: Fix scaling vs. perf_event_enable_on_exec() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=7fce250915ef;p=linux.git 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> --- diff --git a/kernel/events/core.c b/kernel/events/core.c index 75bde93eb76fe..d0030886c4028 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);