From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752340AbZK3JKe (ORCPT ); Mon, 30 Nov 2009 04:10:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751503AbZK3JKd (ORCPT ); Mon, 30 Nov 2009 04:10:33 -0500 Received: from hera.kernel.org ([140.211.167.34]:46500 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750918AbZK3JKd (ORCPT ); Mon, 30 Nov 2009 04:10:33 -0500 Message-ID: <4B138BC8.3090008@kernel.org> Date: Mon, 30 Nov 2009 18:09:28 +0900 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.4pre) Gecko/20090915 SUSE/3.0b4-3.6 Thunderbird/3.0b4 MIME-Version: 1.0 To: Avi Kivity CC: Ingo Molnar , lkml , Ingo Molnar , Linus Torvalds Subject: Re: [PATCH 2.6.32-rc6] sched, kvm: fix race condition involving sched_in_preempt_notifers References: <4AFD2801.7020900@kernel.org> <20091113095516.GD1364@elte.hu> <4AFEAB6D.60600@redhat.com> In-Reply-To: <4AFEAB6D.60600@redhat.com> X-Enigmail-Version: 0.97a Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/14/2009 10:06 PM, Avi Kivity wrote: > On 11/13/2009 11:55 AM, Ingo Molnar wrote: >> * Tejun Heo wrote: >>> In finish_task_switch(), fire_sched_in_preempt_notifiers() is called >>> after finish_lock_switch(). However, depending on architecture, >>> preemption can be enabled after finish_lock_switch() which breaks the >>> semantics of preempt notifiers. Move it before finish_arch_switch(). >>> This also makes in notifiers symmetric to out notifiers in terms of >>> locking - now both are called under rq lock. >>> >>> >> I'd like to have Avi's Ack for it, > > Acked-by: Avi Kivity > >> but we want to do sched.c changes via >> the scheduler tree. So, this one was a bust. Given that the only platform which might have been affected by the original bug is ia64 and it's very unlikely to happen. I think reverting this from sched/urgent would be the right thing to do at this point if the branch is headed for another push to Linus. Avi, what do you think? Thanks. -- tejun