From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Thu, 28 Jan 2010 12:22:58 +0100 (CET) Received: from localhost.localdomain ([127.0.0.1]:55830 "EHLO h5.dl5rb.org.uk" rhost-flags-OK-OK-OK-FAIL) by eddie.linux-mips.org with ESMTP id S1492034Ab0A1LWy (ORCPT ); Thu, 28 Jan 2010 12:22:54 +0100 Received: from h5.dl5rb.org.uk (localhost.localdomain [127.0.0.1]) by h5.dl5rb.org.uk (8.14.3/8.14.3) with ESMTP id o0SBMvus011574; Thu, 28 Jan 2010 12:22:59 +0100 Received: (from ralf@localhost) by h5.dl5rb.org.uk (8.14.3/8.14.3/Submit) id o0SBMsRK011563; Thu, 28 Jan 2010 12:22:54 +0100 Date: Thu, 28 Jan 2010 12:22:52 +0100 From: Ralf Baechle To: Manuel Lauss Cc: Linux-MIPS , Manuel Lauss Subject: Re: [PATCH v2] MIPS: Alchemy: fix dbdma ring destruction memory debugcheck. Message-ID: <20100128112250.GA8043@linux-mips.org> References: <1264534773-24909-1-git-send-email-manuel.lauss@gmail.com> <20100127221818.GB26426@linux-mips.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) X-archive-position: 25709 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips Return-Path: X-Keywords: X-UID: 18134 On Thu, Jan 28, 2010 at 09:23:56AM +0100, Manuel Lauss wrote: > >> This fix is only necessary with the SLAB allocator and CONFIG_DEBUG_SLAB > >> enabled;  non-debug SLAB, SLUB do return nicely aligned addresses, > >> debug-enabled SLUB currently panics early in the boot process. > > > > Queued for 2.6.34 - should this also go into 2.6.33? > > 2.6.33 and .32 at least. That code has been in there since the dawn of 2.6; > the fact that nobody has tripped over this so far means that noone build kernels > with slab debugging (I tripped over this while looking for something else) or > the slab allocator behaviour changed recently. The behaviour of the slab has been like this as long as I can remember. Cherrypicking into the -stable branches as I'm writing this. > > Have you considered increasing the value ARCH_KMALLOC_MINALIGN which > > defaults to 8?  Or your own slab cache of suitable alignment?  The latter > > is more something for frequent allocations. > > I have to admit I know nothing about Linux' memory management. Are slab > caches not affected by the what I presume are "guard bytes" inserted into > the memory areas when slab debug is on? When creating a slab cache an alignment for objects allocated from this cache can be specified. Ralf