Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754305Ab3EAIFe (ORCPT ); Wed, 1 May 2013 04:05:34 -0400 Received: from mail-lb0-f178.google.com ([209.85.217.178]:45454 "EHLO mail-lb0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751228Ab3EAIFX (ORCPT ); Wed, 1 May 2013 04:05:23 -0400 Message-ID: <5180CCC0.8070703@kernel.org> Date: Wed, 01 May 2013 11:05:20 +0300 From: Pekka Enberg User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:17.0) Gecko/20130328 Thunderbird/17.0.5 MIME-Version: 1.0 To: Christoph Lameter CC: Tetsuo Handa , glommer@parallels.com, linux-kernel@vger.kernel.org Subject: Re: [linux-next-20130422] Bug in SLAB? References: <0000013e564e0e5a-121c52f9-e489-470f-99d5-67a5ad42eb75-000000@email.amazonses.com> <201304300028.IAD13051.OHOVMJSLFFFQOt@I-love.SAKURA.ne.jp> <0000013e56e9304a-1042a95a-d4dd-43c5-8b8a-c670f50ac54e-000000@email.amazonses.com> <201304300645.FCE37285.tVHJLSOMQFOFFO@I-love.SAKURA.ne.jp> <0000013e5b56d067-7982dfa6-08a2-4c48-ad77-6888b5114c5f-000000@email.amazonses.com> <201305010101.CGB86424.JFQOtSFOVOLFHM@I-love.SAKURA.ne.jp> <0000013e5bfc7c4d-54fa9464-dccd-4157-b4a5-22594261eaf3-000000@email.amazonses.com> In-Reply-To: <0000013e5bfc7c4d-54fa9464-dccd-4157-b4a5-22594261eaf3-000000@email.amazonses.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 922 Lines: 20 On 4/30/13 8:27 PM, Christoph Lameter wrote: >> "kmalloc() returning NULL for these allocations" is needed by "try kmalloc() >> first, fallback to vmalloc()" allocation. There are kernel modules which expect >> kmalloc() to return NULL rather than oops when the requested size is larger >> than KMALLOC_MAX_SIZE bytes. If kmalloc() suddenly starts triggering oops, such >> modules will break. > > This behavior has been in there for years. Why try a kmalloc that > always fails since the size is too big? ...because want the extra protection for cases where size is controlled by userspace. This is consistent with kcalloc() that returns NULL on integer overflow. Pekka -- 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/