From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752183AbZKNNHw (ORCPT ); Sat, 14 Nov 2009 08:07:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751901AbZKNNHv (ORCPT ); Sat, 14 Nov 2009 08:07:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46154 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751687AbZKNNHv (ORCPT ); Sat, 14 Nov 2009 08:07:51 -0500 Message-ID: <4AFEAB6D.60600@redhat.com> Date: Sat, 14 Nov 2009 15:06:53 +0200 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.4pre) Gecko/20090922 Fedora/3.0-3.9.b4.fc12 Thunderbird/3.0b4 MIME-Version: 1.0 To: Ingo Molnar CC: Tejun Heo , 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> In-Reply-To: <20091113095516.GD1364@elte.hu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > Definitely. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.