From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752622Ab0ESOLx (ORCPT ); Wed, 19 May 2010 10:11:53 -0400 Received: from waste.org ([173.11.57.241]:50954 "EHLO waste.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751873Ab0ESOLv (ORCPT ); Wed, 19 May 2010 10:11:51 -0400 Subject: Re: [BUG] SLOB breaks Crypto From: Matt Mackall To: Geert Uytterhoeven Cc: David Woodhouse , Herbert Xu , David Miller , penberg@cs.helsinki.fi, ken@codelabs.ch, michael-dev@fami-braun.de, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, anemo@mba.ocn.ne.jp In-Reply-To: References: <1274211235.11603.1205.camel@calx> <20100518.135945.180391159.davem@davemloft.net> <20100518.142021.135951273.davem@davemloft.net> <1274224834.6930.8361.camel@macbook.infradead.org> <20100519010524.GB18813@gondor.apana.org.au> <1274253269.6930.9325.camel@macbook.infradead.org> <1274269236.6930.9930.camel@macbook.infradead.org> Content-Type: text/plain; charset="UTF-8" Date: Wed, 19 May 2010 09:11:47 -0500 Message-ID: <1274278307.11603.1264.camel@calx> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2010-05-19 at 13:50 +0200, Geert Uytterhoeven wrote: > On Wed, May 19, 2010 at 13:40, David Woodhouse wrote: > > On Wed, 2010-05-19 at 13:32 +0200, Geert Uytterhoeven wrote: > >> Instead of having (different) defaults in sl[aou]b, perhaps we should > >> just remove the defaults completely, to ensure all architectures set > >> ARCH_SLAB_MINALIGN to the correct value? > > > > What is 'correct'? The architecture sets it to the minimum value that it > > can cope with, according to its own alignment constraints (and DMA/cache > > constraints, in the case of ARCH_KMALLOC_MINALIGN). > > > > Some architectures don't _have_ any minimum required alignment, so they > > have no need to set it. If the architecture _does_ specify a minimum, > > the allocators must honour it. Otherwise, they're free to do their own > > thing. And slob chooses to use a smaller alignment than slab and slub > > do, in accordance with its design and its raison d'être. > > Currently 7 out of 20+ architectures set it. > Any bets on how many are missing, but should set it? I still think we should add it to all of them as positive documentation that this issue has been considered. And then make the kernel not compile without it so new arch implementors can't miss it. -- Mathematics is the supreme nostalgia of our time.