From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760146Ab2CTOOu (ORCPT ); Tue, 20 Mar 2012 10:14:50 -0400 Received: from smtp101.prem.mail.ac4.yahoo.com ([76.13.13.40]:41480 "HELO smtp101.prem.mail.ac4.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1758036Ab2CTOOs (ORCPT ); Tue, 20 Mar 2012 10:14:48 -0400 X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: Gl_oitEVM1nvYmh8o9RCbpDvszopNl.Xt48C13cDKIsOlex 9Xnobnb6ipA1m1C6zJ8iYyMr.9qB9jDDKKqXCDK31Lx4EaNM0B3Oee4SZtDb VecaFNciC5kN6Rd6FB3sGgmhTAabbZ0KRa3A.DfJB9K2vYaRccI3fMn5E7ud .43uN30ABPNJZamJMeiKEr12WL.0bv9tgVnlj4Y4tkHuUcx0UOC6nmW.WVu2 6jMedOS5kQxSwbJtCWz8d2dcOR__RgnoE28kPpnh.Cg1585ntmf1p0ADnYh. ro6FYzXxAQtmvkQoRG.PTKwalMjq_czAIC9kfPa9qsWEuuC1QOvLrnMxf9u5 G1HtgVPIo4.P34TN3RPlQxDVnIkU0z_wJvTmTjqJTpxgyy0Y8.501K0ZpJRp i X-Yahoo-SMTP: _Dag8S.swBC1p4FJKLCXbs8NQzyse1SYSgnAbY0- Date: Tue, 20 Mar 2012 09:14:44 -0500 (CDT) From: Christoph Lameter X-X-Sender: cl@router.home To: Lai Jiangshan cc: Pekka Enberg , Matt Mackall , Tejun Heo , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 2/6] slub: add kmalloc_align() In-Reply-To: <1332238884-6237-3-git-send-email-laijs@cn.fujitsu.com> Message-ID: References: <1332238884-6237-1-git-send-email-laijs@cn.fujitsu.com> <1332238884-6237-3-git-send-email-laijs@cn.fujitsu.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 20 Mar 2012, Lai Jiangshan wrote: > diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h > index a32bcfd..67ac6b4 100644 > --- a/include/linux/slub_def.h > +++ b/include/linux/slub_def.h > @@ -280,6 +280,12 @@ static __always_inline void *kmalloc(size_t size, gfp_t flags) > return __kmalloc(size, flags); > } > > +static __always_inline > +void *kmalloc_align(size_t size, gfp_t flags, size_t align) > +{ > + return kmalloc(ALIGN(size, align), flags); > +} This assumes that kmalloc allocates aligned memory. Which it does only in special cases (power of two cache and debugging off). > #ifdef CONFIG_NUMA > void *__kmalloc_node(size_t size, gfp_t flags, int node); > void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node); > diff --git a/mm/slub.c b/mm/slub.c > index 4907563..01cf99d 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -3238,7 +3238,7 @@ static struct kmem_cache *__init create_kmalloc_cache(const char *name, > * This function is called with IRQs disabled during early-boot on > * single CPU so there's no need to take slub_lock here. > */ > - if (!kmem_cache_open(s, name, size, ARCH_KMALLOC_MINALIGN, > + if (!kmem_cache_open(s, name, size, ALIGN_OF_LAST_BIT(size), > flags, NULL)) > goto panic; Why does the alignment of struct kmem_cache change? I'd rather have a __alignof__(struct kmem_cache) here with alignment specified with the struct definition.