From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 9FAF58D003B for ; Tue, 19 Apr 2011 17:23:40 -0400 (EDT) Received: from kpbe13.cbf.corp.google.com (kpbe13.cbf.corp.google.com [172.25.105.77]) by smtp-out.google.com with ESMTP id p3JLNcaQ031282 for ; Tue, 19 Apr 2011 14:23:38 -0700 Received: from pzk30 (pzk30.prod.google.com [10.243.19.158]) by kpbe13.cbf.corp.google.com with ESMTP id p3JLMiJV032484 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Tue, 19 Apr 2011 14:23:36 -0700 Received: by pzk30 with SMTP id 30so67102pzk.3 for ; Tue, 19 Apr 2011 14:23:36 -0700 (PDT) Date: Tue, 19 Apr 2011 14:23:35 -0700 (PDT) From: David Rientjes Subject: Re: [PATCH 1/2] break out page allocation warning code In-Reply-To: <1303160221.9887.301.camel@nimitz> Message-ID: References: <20110415170437.17E1AF36@kernel> <1303139455.9615.2533.camel@nimitz> <1303160221.9887.301.camel@nimitz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , Michal Nazarewicz , Andrew Morton On Mon, 18 Apr 2011, Dave Hansen wrote: > > It shouldn't be a follow-on patch since you're introducing a new feature > > here (vmalloc allocation failure warnings) and what I'm identifying is a > > race in the access to current->comm. A bug fix for a race should always > > preceed a feature that touches the same code. > > Dude. Seriously. Glass house! a63d83f4 > Not sure what you're implying here. The commit you've identified is the oom killer rewrite and the oom killer is very specific about making sure to always hold task_lock() whenever dereferencing ->comm, even for current, to guard against /proc/pid/comm or prctl(). The oom killer is different from your usecase, however, because we can always take task_lock(current) in the oom killer because it's in a blockable context, whereas page allocation warnings can occur in a superset. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org