Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753548Ab2JPGKO (ORCPT ); Tue, 16 Oct 2012 02:10:14 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:37705 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751317Ab2JPGKM (ORCPT ); Tue, 16 Oct 2012 02:10:12 -0400 Date: Mon, 15 Oct 2012 23:10:09 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: KOSAKI Motohiro cc: Dave Jones , Linux Kernel , bhutchings@solarflare.com, linux-mm@kvack.org, Linus Torvalds , Andrew Morton Subject: Re: mpol_to_str revisited. In-Reply-To: Message-ID: References: <20121008150949.GA15130@redhat.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1237 Lines: 30 On Tue, 16 Oct 2012, KOSAKI Motohiro wrote: > >> I don't think 80de7c3138ee9fd86a98696fd2cf7ad89b995d0a is right fix. > > > > It's certainly not a complete fix, but I think it's a much better result > > of the race, i.e. we don't panic anymore, we simply fail the read() > > instead. > > Even though 80de7c3138ee9fd86a98696fd2cf7ad89b995d0a itself is simple. It bring > to caller complex. That's not good and have no worth. > Before: the kernel panics, all workloads cease. After: the file shows garbage, all workloads continue. This is better, in my opinion, but at best it's only a judgment call and has no effect on anything. I agree it would be better to respect the return value of mpol_to_str() since there are other possible error conditions other than a freed mempolicy, but let's not consider reverting 80de7c3138. It is obviously not a full solution to the problem, though, and we need to serialize with task_lock(). Dave, are you interested in coming up with a patch? -- 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/