Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933421Ab0LUBeD (ORCPT ); Mon, 20 Dec 2010 20:34:03 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:59993 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933384Ab0LUBeC (ORCPT ); Mon, 20 Dec 2010 20:34:02 -0500 X-Authority-Analysis: v=1.1 cv=+c36koQ5Dcj/1qolKHjtkYAGXvrVJRRiKMp+84F5sLg= c=1 sm=0 a=GT7j54JQFWIA:10 a=Q9fys5e9bTEA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=omOdbC7AAAAA:8 a=eCrDwqJm5saGu0qYzWEA:9 a=4J10diSZ6zW2UDxY66LkFQRYA7AA:4 a=PUjeQqilurYA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Subject: Re: [PATCH] tracing: Fix preempt count leak From: Steven Rostedt To: Li Zefan Cc: Frederic Weisbecker , Jiri Olsa , LKML , Hiroyuki KAMEZAWA In-Reply-To: <4D0FFB1A.7070407@cn.fujitsu.com> References: <4D0089AC.1020802@cn.fujitsu.com> <4D0FFB1A.7070407@cn.fujitsu.com> Content-Type: text/plain; charset="ISO-8859-15" Date: Mon, 20 Dec 2010 20:33:59 -0500 Message-ID: <1292895239.22905.67.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1812 Lines: 58 On Tue, 2010-12-21 at 08:55 +0800, Li Zefan wrote: > Any comment? oops, this was buried in my email. I'll look at it tomorrow. -- Steve > > 15:47, Li Zefan wrote: > > While running my ftrace stress test, this showed up: > > > > BUG: sleeping function called from invalid context at mm/mmap.c:233 > > ... > > note: cat[3293] exited with preempt_count 1 > > > > The bug was introduced by commit 91e86e560d0b3ce4c5fc64fd2bbb99f856a30a4e > > ("tracing: Fix recursive user stack trace") > > > > Signed-off-by: Li Zefan > > --- > > kernel/trace/trace.c | 6 ++---- > > 1 files changed, 2 insertions(+), 4 deletions(-) > > > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > > index c380612..5767457 100644 > > --- a/kernel/trace/trace.c > > +++ b/kernel/trace/trace.c > > @@ -1313,12 +1313,10 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc) > > > > __this_cpu_inc(user_stack_count); > > > > - > > - > > event = trace_buffer_lock_reserve(buffer, TRACE_USER_STACK, > > sizeof(*entry), flags, pc); > > if (!event) > > - return; > > + goto out_drop_count; > > entry = ring_buffer_event_data(event); > > > > entry->tgid = current->tgid; > > @@ -1333,8 +1331,8 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc) > > if (!filter_check_discard(call, entry, buffer, event)) > > ring_buffer_unlock_commit(buffer, event); > > > > + out_drop_count: > > __this_cpu_dec(user_stack_count); > > - > > out: > > preempt_enable(); > > } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/