From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756327Ab0BEJBx (ORCPT ); Fri, 5 Feb 2010 04:01:53 -0500 Received: from out02.mta.xmission.com ([166.70.13.232]:41855 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753633Ab0BEJBw (ORCPT ); Fri, 5 Feb 2010 04:01:52 -0500 To: Amerigo Wang Cc: linux-kernel@vger.kernel.org, Tejun Heo , Greg Kroah-Hartman , Peter Zijlstra , Miles Lane , Heiko Carstens , Benjamin Herrenschmidt , Larry Finger , akpm@linux-foundation.org Subject: Re: [Patch v2] sysfs: add lockdep class support to s_active References: <20100205064622.4141.72867.sendpatchset@localhost.localdomain> From: ebiederm@xmission.com (Eric W. Biederman) Date: Fri, 05 Feb 2010 01:01:47 -0800 In-Reply-To: <20100205064622.4141.72867.sendpatchset@localhost.localdomain> (Amerigo Wang's message of "Fri\, 5 Feb 2010 01\:42\:56 -0500") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=76.21.114.89;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 76.21.114.89 X-SA-Exim-Mail-From: ebiederm@xmission.com X-SA-Exim-Scanned: No (on in01.mta.xmission.com); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Amerigo Wang writes: > Recently we met a lockdep warning from sysfs during s2ram or cpu hotplug. > As reported by several people, it is something like: The interesting case is the cpu hotplug is actually a problem. It isn't useful to get a complaint about the non-problems code paths triggered by pm. However my earlier review spotted a real deadlock case. Where in one of the sysfs attributes we iterate over the list of online cpus and that appeared to an attribute that removing a cpu would remove from sysfs... Eric