Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755933Ab1DSVXp (ORCPT ); Tue, 19 Apr 2011 17:23:45 -0400 Received: from smtp-out.google.com ([74.125.121.67]:56348 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754174Ab1DSVXo (ORCPT ); Tue, 19 Apr 2011 17:23:44 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version:content-type; b=Yqt7VziEFl8ZY1c7GI3h0x5crwkVUQs2N3YLogSFaRol3ycfP7k0qM1XCupm1Jm3Qb V6YVr+ezxKpf87Jav/8g== Date: Tue, 19 Apr 2011 14:23:35 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Dave Hansen cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , Michal Nazarewicz , Andrew Morton 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> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1109 Lines: 22 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 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/