Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756693Ab0FSTWM (ORCPT ); Sat, 19 Jun 2010 15:22:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49464 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751310Ab0FSTWK (ORCPT ); Sat, 19 Jun 2010 15:22:10 -0400 Date: Sat, 19 Jun 2010 21:19:09 +0200 From: Oleg Nesterov To: Mandeep Baines Cc: Andrew Morton , Don Zickus , Frederic Weisbecker , Ingo Molnar , Jerome Marchand , Roland McGrath , linux-kernel@vger.kernel.org, stable@kernel.org, "Eric W. Biederman" , "Paul E. McKenney" Subject: Re: while_each_thread() under rcu_read_lock() is broken? Message-ID: <20100619191909.GA4384@redhat.com> References: <20100618190251.GA17297@redhat.com> <20100618193403.GA17314@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 844 Lines: 24 On 06/18, Mandeep Baines wrote: > > On Fri, Jun 18, 2010 at 12:34 PM, Oleg Nesterov wrote: > > > > > > I _really_ hope I missed something, will recheck tomorrow with the fresh > > head. Still I'd like to share my concerns... > > Yep. You're right. Not sure what I was thinking. This is only case > where do_each_thread > is protected by an rcu_read_lock. All others, correctly use read_lock. No, no. while_each_thread() is supposed to be rcu-safe, we should fix it. It has many rcu_read_lock() users. The patch which fixes rcu_lock_break() is orthogonal to this problem. Oleg. -- 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/