From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757434AbcASTi5 (ORCPT ); Tue, 19 Jan 2016 14:38:57 -0500 Received: from mail-pf0-f176.google.com ([209.85.192.176]:35951 "EHLO mail-pf0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755652AbcASTis (ORCPT ); Tue, 19 Jan 2016 14:38:48 -0500 Date: Tue, 19 Jan 2016 14:38:45 -0500 From: Tejun Heo To: Christian Borntraeger Cc: Heiko Carstens , Peter Zijlstra , "linux-kernel@vger.kernel.org >> Linux Kernel Mailing List" , linux-s390 , KVM list , Oleg Nesterov , "Paul E. McKenney" Subject: Re: regression 4.4: deadlock in with cgroup percpu_rwsem Message-ID: <20160119193845.GT3520@mtj.duckdns.org> References: <56978452.6010606@de.ibm.com> <20160114195630.GA3520@mtj.duckdns.org> <5698A023.9070703@de.ibm.com> <56990C9E.7020801@de.ibm.com> <20160118183205.GW6357@twins.programming.kicks-ass.net> <569D3370.6040503@de.ibm.com> <20160119095518.GC3528@osiris> <569E9032.3070903@de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <569E9032.3070903@de.ibm.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Tue, Jan 19, 2016 at 08:36:18PM +0100, Christian Borntraeger wrote: > No, its not a task_struct. Activating some more debug information did indeed > revealed several other issues (overwritten redzones etc). Unfortunately I > only saw the broken things after the facts, so I do not know which code did that. > When I disabled the cgroup controllers in libvirt I was no longer able to trigger > the bugs. Still trying to narrow things down. Hmmm... that's worrying. CONFIG_DEBUG_PAGEALLOC sometimes can catch these sort of bugs red-handed. Might worth trying. Thanks. -- tejun