Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263231AbTIVQdN (ORCPT ); Mon, 22 Sep 2003 12:33:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263232AbTIVQdN (ORCPT ); Mon, 22 Sep 2003 12:33:13 -0400 Received: from zeus.kernel.org ([204.152.189.113]:10665 "EHLO zeus.kernel.org") by vger.kernel.org with ESMTP id S263231AbTIVQdJ (ORCPT ); Mon, 22 Sep 2003 12:33:09 -0400 Message-ID: <3F6F23DA.9020901@colorfullife.com> Date: Mon, 22 Sep 2003 18:31:22 +0200 From: Manfred Spraul User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030701 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Arnd Bergmann CC: linux-kernel@vger.kernel.org, linux-mm@vger.kernel.org Subject: Re: [PATCH] Move slab objects to the end of the real allocation References: <200309221733.37203.arnd@arndb.de> In-Reply-To: <200309221733.37203.arnd@arndb.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1506 Lines: 39 Arnd Bergmann wrote: >Manfred Spraul wrote: > > >> - Do not page-pad allocations that are <= SMP_CACHE_LINE_SIZE. This >> crashes. Right now the limit is hardcoded to 128 bytes, but sooner or >> later an arch will appear with 256 byte cache lines. >> >> > >What made you think that 128 is the current maximum? All s390 machines >have 256 byte cache lines. > > When I wrote "128" I was not aware that this is linked to the cache line size. Initially it was ">128", just as an arbitrary number. I replaced that with "> 116" due to an unrelated change, and that crashed, because the cache line size was set to 128 bytes. My patch fixes this bug: It replaces the limits with >=116 [avoid wasting too much memory, guarantee that there is a cache for the off-slab control structures] and > SMP_CACHE_LINE_SIZE [guarantee that there is a cache for the off-slab control structures]. Right now there are too many patches in Andrew's tree, I'll wait until everything settled down a bit, then I'll resent the cache line size as a one-line patch. Do you want to implement CONFIG_DEBUG_PAGEALLOC immediately? If yes, then I can send you the oneliner immediately. Nothing except CONFIG_DEBUG_PAGEALLOC is affected by the bug. -- Manfred - 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/