Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752520Ab3FXQv5 (ORCPT ); Mon, 24 Jun 2013 12:51:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:28799 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750964Ab3FXQvz (ORCPT ); Mon, 24 Jun 2013 12:51:55 -0400 Date: Mon, 24 Jun 2013 12:51:40 -0400 From: Dave Jones To: Steven Rostedt Cc: Oleg Nesterov , "Paul E. McKenney" , Linux Kernel , Linus Torvalds , "Eric W. Biederman" , Andrey Vagin Subject: Re: frequent softlockups with 3.10rc6. Message-ID: <20130624165140.GB8572@redhat.com> Mail-Followup-To: Dave Jones , Steven Rostedt , Oleg Nesterov , "Paul E. McKenney" , Linux Kernel , Linus Torvalds , "Eric W. Biederman" , Andrey Vagin References: <20130622173129.GA29375@redhat.com> <20130622215905.GA28238@redhat.com> <20130623143634.GA2000@redhat.com> <20130623150603.GA32313@redhat.com> <20130623160452.GA11740@redhat.com> <20130624020014.GB12811@redhat.com> <20130624143928.GA20659@redhat.com> <1372085549.18733.162.camel@gandalf.local.home> <20130624160012.GB5993@redhat.com> <1372091079.18733.168.camel@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1372091079.18733.168.camel@gandalf.local.home> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1115 Lines: 24 On Mon, Jun 24, 2013 at 12:24:39PM -0400, Steven Rostedt wrote: > > Ah, this is the first victim of my new 'check sanity of nodes during list walks' patch. > > It's doing the same prev->next next->prev checking as list_add and friends. > > I'm looking at getting it into shape for a 3.12 merge after some other preparatory patches > > go into 3.11 > > OK, and you may need to make an exception for the ring buffer. To do a > lockless swap out of the reader page for one of the pages in the buffer, > it uses the 2 LSB as flags. Notice the "next=ffff880243288001", that "1" > is a flag that states the next page is the "header" page (next to be > read). We use cmpxchg to update the pages to handle races between the > reader and writer. I just had a plumber come visit to replace my toilet. I think even he would say "dude, gross" about that hack. Dave -- 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/