From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id BEFE28D003B for ; Tue, 19 Apr 2011 20:39:05 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id AAB443EE0BD for ; Wed, 20 Apr 2011 09:39:02 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 0F99445DE92 for ; Wed, 20 Apr 2011 09:39:02 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id EC5FB45DE8F for ; Wed, 20 Apr 2011 09:39:01 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id DF78EE08002 for ; Wed, 20 Apr 2011 09:39:01 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.240.81.145]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id A0D66E08001 for ; Wed, 20 Apr 2011 09:39:01 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH 1/2] break out page allocation warning code In-Reply-To: References: <20110419094422.9375.A69D9226@jp.fujitsu.com> Message-Id: <20110420093900.45F6.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Wed, 20 Apr 2011 09:39:00 +0900 (JST) Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: kosaki.motohiro@jp.fujitsu.com, Dave Hansen , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , Michal Nazarewicz , Andrew Morton > On Tue, 19 Apr 2011, KOSAKI Motohiro wrote: > > > The rule is, > > > > 1) writing comm > > need task_lock > > 2) read _another_ thread's comm > > need task_lock > > 3) read own comm > > no need task_lock > > > > That was true a while ago, but you now need to protect every thread's > ->comm with get_task_comm() or ensuring task_lock() is held to protect > against /proc/pid/comm which can change other thread's ->comm. That was > different before when prctl(PR_SET_NAME) would only operate on current, so > no lock was needed when reading current->comm. Right. /proc/pid/comm is evil. We have to fix it. otherwise we need change all of current->comm user. It's very lots! -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org