Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752987AbdGFXRV (ORCPT ); Thu, 6 Jul 2017 19:17:21 -0400 Received: from mail-oi0-f45.google.com ([209.85.218.45]:35663 "EHLO mail-oi0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752737AbdGFXRT (ORCPT ); Thu, 6 Jul 2017 19:17:19 -0400 MIME-Version: 1.0 In-Reply-To: <20170706085902.0af6c9a6@gandalf.local.home> References: <20170706001147.29213-1-joelaf@google.com> <20170706085902.0af6c9a6@gandalf.local.home> From: Joel Fernandes Date: Thu, 6 Jul 2017 16:17:18 -0700 Message-ID: Subject: Re: [PATCH] tracing: Fix issues recording task information To: Steven Rostedt Cc: LKML , Michael Sartain , kernel-team@android.com, Ingo Molnar Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1225 Lines: 37 Hi Steven, On Thu, Jul 6, 2017 at 5:59 AM, Steven Rostedt wrote: [..] >> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c >> index b66a1c8805f3..27b981a46389 100644 >> --- a/kernel/trace/trace.c >> +++ b/kernel/trace/trace.c >> @@ -1918,7 +1918,11 @@ static int trace_save_cmdline(struct task_struct *tsk) >> { >> unsigned pid, idx; >> >> - if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT)) >> + /* treat recording of idle task as a success */ >> + if (!tsk->pid) >> + return 1; >> + >> + if (unlikely(tsk->pid > PID_MAX_DEFAULT)) >> return 0; > > Make this a separate patch. This should go to stable. Actually I am not sure if this should be marked for stable since before we were doing: tracing_record_cmdline(prev); tracing_record_cmdline(next); in probe_sched_switch, thus even if prev was the idle task, it would still goto record the next. IMO it becomes an issue only with the new stuff where we record cmdline for prev and next in the same call (tracing_record_taskinfo_sched_switch). Anyway I already broke it up into a different patch and sent it out. Let me know if anything else needs to be done here, thanks. Regards, -Joel