From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-f197.google.com (mail-yw0-f197.google.com [209.85.161.197]) by kanga.kvack.org (Postfix) with ESMTP id F2A176B02B4 for ; Mon, 7 Aug 2017 13:48:47 -0400 (EDT) Received: by mail-yw0-f197.google.com with SMTP id n83so15315051ywn.10 for ; Mon, 07 Aug 2017 10:48:47 -0700 (PDT) Received: from mail-qk0-f178.google.com (mail-qk0-f178.google.com. [209.85.220.178]) by mx.google.com with ESMTPS id t38si2235189ybi.380.2017.08.07.10.48.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Aug 2017 10:48:47 -0700 (PDT) Received: by mail-qk0-f178.google.com with SMTP id u139so6783816qka.1 for ; Mon, 07 Aug 2017 10:48:47 -0700 (PDT) Subject: Re: [RFC][PATCH] mm/slub.c: Allow poisoning to use the fast path References: <20170804231002.20362-1-labbott@redhat.com> From: Laura Abbott Message-ID: <559096f0-bf1b-eff1-f0ce-33f53a4df255@redhat.com> Date: Mon, 7 Aug 2017 10:48:42 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: 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 On 08/07/2017 07:37 AM, Christopher Lameter wrote: > On Fri, 4 Aug 2017, Laura Abbott wrote: > >> All slub debug features currently disable the fast path completely. >> Some features such as consistency checks require this to allow taking of >> locks. Poisoning and red zoning don't require this and can safely use >> the per-cpu fast path. Introduce a Kconfig to continue to use the fast >> path when 'fast' debugging options are enabled. The code will >> automatically revert to always using the slow path when 'slow' options >> are enabled. > > 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. Thanks, Laura -- 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/ . Don't email: email@kvack.org