Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752743Ab3JBCWk (ORCPT ); Tue, 1 Oct 2013 22:22:40 -0400 Received: from zene.cmpxchg.org ([85.214.230.12]:56124 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751974Ab3JBCWh (ORCPT ); Tue, 1 Oct 2013 22:22:37 -0400 Date: Tue, 1 Oct 2013 22:22:27 -0400 From: Johannes Weiner To: David Rientjes Cc: Linus Torvalds , Andrew Morton , Michal Hocko , KAMEZAWA Hiroyuki , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [patch for-3.12] mm, memcg: protect mem_cgroup_read_events for cpu hotplug Message-ID: <20131002022227.GR856@cmpxchg.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 844 Lines: 23 On Tue, Oct 01, 2013 at 04:31:23PM -0700, David Rientjes wrote: > for_each_online_cpu() needs the protection of {get,put}_online_cpus() so > cpu_online_mask doesn't change during the iteration. There is no problem report here. Is there a crash? If it's just accuracy of the read, why would we care about some inaccuracies in counters that can change before you even get the results to userspace? And care to the point where we hold up CPU hotplugging for this? Also, the fact that you directly sent this to Linus suggests there is some urgency for this fix. What's going on? Thanks, Johannes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/