From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753932AbbIPOQh (ORCPT ); Wed, 16 Sep 2015 10:16:37 -0400 Received: from mail-yk0-f180.google.com ([209.85.160.180]:34776 "EHLO mail-yk0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753696AbbIPOQe (ORCPT ); Wed, 16 Sep 2015 10:16:34 -0400 Date: Wed, 16 Sep 2015 10:16:30 -0400 From: Tejun Heo To: Oleg Nesterov Cc: Paolo Bonzini , Christian Borntraeger , paulmck@linux.vnet.ibm.com, Peter Zijlstra , Ingo Molnar , "linux-kernel@vger.kernel.org >> Linux Kernel Mailing List" , KVM list Subject: Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Message-ID: <20150916141630.GA3243@mtj.duckdns.org> References: <55F8097A.7000206@de.ibm.com> <20150915130550.GC16853@twins.programming.kicks-ass.net> <55F81EE2.4090708@de.ibm.com> <55F84A6B.1010207@redhat.com> <20150915173836.GO4029@linux.vnet.ibm.com> <55F92904.4090206@redhat.com> <55F92F04.1040706@de.ibm.com> <55F9326A.9070509@redhat.com> <20150916122249.GA28821@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150916122249.GA28821@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, Sep 16, 2015 at 02:22:49PM +0200, Oleg Nesterov wrote: > > If the revert isn't easy, I think backporting rcu_sync is the best bet. > > I leave this to Paul and Tejun... at least I think this is not v4.2 material. Will route reverts through cgroup branch. Should be pretty painless. Nice job on percpu_rwsem. It's so much better than having to come up with a separate middleground solution. Thanks. -- tejun