Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753955Ab0HTAI5 (ORCPT ); Thu, 19 Aug 2010 20:08:57 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:53256 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752724Ab0HTAIz (ORCPT ); Thu, 19 Aug 2010 20:08:55 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: David Howells Subject: Re: oom: __task_cred() need rcu_read_lock() Cc: kosaki.motohiro@jp.fujitsu.com, "Paul E. McKenney" , LKML , linux-mm , Andrew Morton , David Rientjes , KAMEZAWA Hiroyuki In-Reply-To: <7682.1282230394@redhat.com> References: <20100819220338.5FD5.A69D9226@jp.fujitsu.com> <7682.1282230394@redhat.com> Message-Id: <20100820084820.5FDB.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Fri, 20 Aug 2010 09:08:52 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 850 Lines: 27 Hi > KOSAKI Motohiro wrote: > > > dump_tasks() can call __task_cred() safely because we are holding > > tasklist_lock. but rcu lock validator don't have enough knowledge and > > it makes following annoying warning. > > No, it can't. The tasklist_lock is not protection against the creds changing > on another CPU. Thank you for correction. I suppose you mean I missed CONFIG_TREE_PREEMPT_RCU, right? As far as my grepping, other rcu implementation and spinlock use preempt_disable(). In other word, Can I assume usual distro user don't hit this issue? Thanks. -- 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/