Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751986AbdHGWAu (ORCPT ); Mon, 7 Aug 2017 18:00:50 -0400 Received: from mail-qt0-f179.google.com ([209.85.216.179]:32827 "EHLO mail-qt0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751743AbdHGWAt (ORCPT ); Mon, 7 Aug 2017 18:00:49 -0400 Subject: Re: [RFC][PATCH] mm/slub.c: Allow poisoning to use the fast path To: Christopher Lameter Cc: Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kees Cook , Rik van Riel References: <20170804231002.20362-1-labbott@redhat.com> <559096f0-bf1b-eff1-f0ce-33f53a4df255@redhat.com> From: Laura Abbott Message-ID: Date: Mon, 7 Aug 2017 15:00:44 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 862 Lines: 21 On 08/07/2017 11:03 AM, Christopher Lameter wrote: > On Mon, 7 Aug 2017, Laura Abbott wrote: > >>> Ok I see that the objects are initialized with poisoning and redzoning but >>> I do not see that there is fastpath code to actually check the values >>> before the object is reinitialized. Is that intentional or am >>> I missing something? >> >> Yes, that's intentional here. I see the validation as a separate more >> expensive feature. I had a crude patch to do some checks for testing >> and I know Daniel Micay had an out of tree patch to do some checks >> as well. > > Ok then this patch does nothing? How does this help? The purpose of this patch is to ensure the poisoning can happen without too much penalty. Even if there aren't checks to abort/warn when there is a problem, there's still value in ensuring objects are always poisoned. Thanks, Laura