From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753766AbZKDGtA (ORCPT ); Wed, 4 Nov 2009 01:49:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753253AbZKDGss (ORCPT ); Wed, 4 Nov 2009 01:48:48 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125]:48318 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752830AbZKDGsq (ORCPT ); Wed, 4 Nov 2009 01:48:46 -0500 Message-Id: <20091104064850.522343875@goodmis.org> User-Agent: quilt/0.48-1 Date: Wed, 04 Nov 2009 01:48:26 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Frederic Weisbecker , KOSAKI Motohiro , Lai Jiangshan Subject: [PATCH 1/2] [PATCH 1/2] ring-buffer: Synchronize resizing buffer with reader lock References: <20091104064825.546743711@goodmis.org> Content-Disposition: inline; filename=0001-ring-buffer-Synchronize-resizing-buffer-with-reader-.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lai Jiangshan We got a sudden panic when we reduced the size of the ringbuffer. We can reproduce the panic by the following steps: echo 1 > events/sched/enable cat trace_pipe > /dev/null & while ((1)) do echo 12000 > buffer_size_kb echo 512 > buffer_size_kb done (not more than 5 seconds, panic ...) Reported-by: KOSAKI Motohiro Signed-off-by: Lai Jiangshan LKML-Reference: <4AF01735.9060409@cn.fujitsu.com> Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 3ffa502..5dd017f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1193,6 +1193,7 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) atomic_inc(&cpu_buffer->record_disabled); synchronize_sched(); + spin_lock_irq(&cpu_buffer->reader_lock); rb_head_page_deactivate(cpu_buffer); for (i = 0; i < nr_pages; i++) { @@ -1207,6 +1208,7 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) return; rb_reset_cpu(cpu_buffer); + spin_unlock_irq(&cpu_buffer->reader_lock); rb_check_pages(cpu_buffer); -- 1.6.3.3