From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757236AbYGCWxh (ORCPT ); Thu, 3 Jul 2008 18:53:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755857AbYGCWx3 (ORCPT ); Thu, 3 Jul 2008 18:53:29 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:46786 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755808AbYGCWx3 (ORCPT ); Thu, 3 Jul 2008 18:53:29 -0400 Date: Thu, 3 Jul 2008 15:53:02 -0700 From: Andrew Morton To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, torvalds@linux-foundation.org, akpm@linuxfoundation.org, peterz@infradead.org, stable@kernel.org Subject: Re: [PATCH] hrtimer: prevent migration for raising softirq Message-Id: <20080703155302.5f86d8f4.akpm@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 3 Jul 2008 14:31:26 -0400 (EDT) Steven Rostedt wrote: > Due to a possible deadlock, the waking of the softirq was pushed outside > of the hrtimer base locks. See commit 0c96c5979a522c3323c30a078a70120e29b5bdbc Please quote at least the patch title rather than raw hashes. afaict that patch isn't in 2.6.25 yet you copied stable@kernel.org. Please clarify. > > Unfortunately this allows the task to migrate after setting up the softirq > and raising it. Since softirqs run a queue that is per-cpu we may raise the > softirq on the wrong CPU and this will keep the queued softirq task from > running. > > To solve this issue, this patch disables preemption around the releasing > of the hrtimer lock and raising of the softirq. > This seems to be 2.6.26 material and is inapplicable to 2.6.25?