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 4ABE78D003B for ; Mon, 25 Apr 2011 00:21:34 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id D1DFC3EE0B5 for ; Mon, 25 Apr 2011 13:21:29 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id BA2D845DE96 for ; Mon, 25 Apr 2011 13:21:29 +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 A1A4945DE93 for ; Mon, 25 Apr 2011 13:21:29 +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 93D16E08001 for ; Mon, 25 Apr 2011 13:21:29 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.240.81.134]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 61C521DB8037 for ; Mon, 25 Apr 2011 13:21:29 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH 1/2] break out page allocation warning code In-Reply-To: <20110421103009.731B.A69D9226@jp.fujitsu.com> References: <1303331695.2796.159.camel@work-vm> <20110421103009.731B.A69D9226@jp.fujitsu.com> Message-Id: <20110425132333.266E.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Date: Mon, 25 Apr 2011 13:21:28 +0900 (JST) Sender: owner-linux-mm@kvack.org List-ID: To: john stultz Cc: kosaki.motohiro@jp.fujitsu.com, David Rientjes , Dave Hansen , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , Michal Nazarewicz , Andrew Morton > > > I'd prefer that we remove /proc/pid/comm entirely or at least prevent > > > writing to it unless CONFIG_EXPERT. > > > > Eeeh. That's probably going to be a tough sell, as I think there is > > wider interest in what it provides. Its useful for debugging > > applications not kernels, so I doubt folks will want to rebuild their > > kernel to try to analyze a java issue. > > > > So I'm well aware that there is the chance that you catch the race and > > read an incomplete/invalid comm (it was discussed at length when the > > change went in), but somewhere I've missed how that's causing actual > > problems. Other then just being "evil" and having the documented race, > > could you clarify what the issue is that your hitting? > > The problem is, there is no documented as well. Okay, I recognized you > introduced new locking rule for task->comm. But there is no documented > it. Thus, We have no way to review current callsites are correct or not. > Can you please do it? And, I have a question. Do you mean now task->comm > reader don't need task_lock() even if it is another thread? > > _if_ every task->comm reader have to realize it has a chance to read > incomplete/invalid comm, task_lock() doesn't makes any help. ping? -- 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