From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751307Ab3FDWlL (ORCPT ); Tue, 4 Jun 2013 18:41:11 -0400 Received: from 1wt.eu ([62.212.114.60]:35143 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751777Ab3FDWkm (ORCPT ); Tue, 4 Jun 2013 18:40:42 -0400 Message-Id: <20130604172130.594554467@1wt.eu> User-Agent: quilt/0.48-1 Date: Tue, 04 Jun 2013 19:21:37 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Mike Galbraith , Thomas Gleixner , Greg Kroah-Hartman , Willy Tarreau Subject: [ 007/184] tick: Cleanup NOHZ per cpu data on cpu down In-Reply-To: <58df134a4b98edf5b0073e2e1e988fe6@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner commit 4b0c0f294f60abcdd20994a8341a95c8ac5eeb96 upstream. Prarit reported a crash on CPU offline/online. The reason is that on CPU down the NOHZ related per cpu data of the dead cpu is not cleaned up. If at cpu online an interrupt happens before the per cpu tick device is registered the irq_enter() check potentially sees stale data and dereferences a NULL pointer. Cleanup the data after the cpu is dead. Reported-by: Prarit Bhargava Cc: Mike Galbraith Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305031451561.2886@ionos Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman Signed-off-by: Willy Tarreau --- kernel/time/tick-sched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index b63cfeb..9f0fd18 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -765,7 +765,7 @@ void tick_cancel_sched_timer(int cpu) hrtimer_cancel(&ts->sched_timer); # endif - ts->nohz_mode = NOHZ_MODE_INACTIVE; + memset(ts, 0, sizeof(*ts)); } #endif -- 1.7.12.2.21.g234cd45.dirty