Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758539Ab0DHHuM (ORCPT ); Thu, 8 Apr 2010 03:50:12 -0400 Received: from mail.windriver.com ([147.11.1.11]:42054 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757897Ab0DHHuJ (ORCPT ); Thu, 8 Apr 2010 03:50:09 -0400 Date: Thu, 8 Apr 2010 15:50:03 +0800 From: Yong Zhang To: Liang Li Cc: "Rafael J. Wysocki" , Linux Kernel Mailing List , Kernel Testers List , Maciej Rutecki , Amit Shah Subject: Re: [Bug #15615] NULL pointer deref in task_is_waking Message-ID: <20100408075003.GC12905@windriver.com> Reply-To: Yong Zhang References: <6Pphclm24fK.A.lSF.qsPvLB@chimera> <20100408071617.GC26543@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20100408071617.GC26543@localhost> User-Agent: Mutt/1.5.20 (2009-06-14) X-OriginalArrivalTime: 08 Apr 2010 07:50:04.0966 (UTC) FILETIME=[19F80460:01CAD6F0] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2678 Lines: 76 On Thu, Apr 08, 2010 at 03:16:17PM +0800, Liang Li wrote: > On Wed, Apr 07, 2010 at 11:13:48PM +0200, Rafael J. Wysocki wrote: > > This message has been generated automatically as a part of a summary report > > of recent regressions. > > > > The following bug entry is on the current list of known regressions > > from 2.6.33. Please verify if it still should be listed and let the tracking team > > know (either way). > > The bug still there. I just met it. And seems its quite simple to get it > fixed. > > diff --git a/kernel/sched.c b/kernel/sched.c > index a3dff1f..2df1a76 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -913,7 +913,7 @@ static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) > */ > static inline int task_is_waking(struct task_struct *p) > { > - return unlikely((p->state == TASK_WAKING) && !(p->flags & PF_STARTING)); > + return unlikely(p && (p->state == TASK_WAKING) && !(p->flags & PF_STARTING)); > } Oh, NO. This is wrong. It will introduce other bugs. The right direction is showed in the bug entry. Thanks, Yong > > /* > > But seems commitid 0017d735092844118bef006696a750a0e4ef6ebd in tip tree > also touched task_is_waking. So the patch for tip tree should be: > > diff --git a/kernel/sched.c b/kernel/sched.c > index 3acf694..d259641 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -920,7 +920,7 @@ static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) > */ > static inline int task_is_waking(struct task_struct *p) > { > - return unlikely(p->state == TASK_WAKING); > + return unlikely(p && p->state == TASK_WAKING); > } > > /* > > Regards, > -Liang Li > > > > > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=15615 > > Subject : NULL pointer deref in task_is_waking > > Submitter : Amit Shah > > Date : 2010-03-23 04:04 (16 days old) > > > > > > -- > > 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/ > -- > 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/ -- 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/