From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id AD9956B004D for ; Fri, 22 May 2009 06:17:39 -0400 (EDT) Date: Fri, 22 May 2009 19:47:33 +0930 From: Ron Subject: Re: [PATCH] slab: add missing guard for kernel_map_pages() use Message-ID: <20090522101733.GA12967@homer.shelbyville.oz> References: <20090521192822.GB4448@homer.shelbyville.oz> <1242979372.13681.1.camel@penberg-laptop> <20090522085040.GC4448@homer.shelbyville.oz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090522085040.GC4448@homer.shelbyville.oz> Sender: owner-linux-mm@kvack.org To: Pekka Enberg Cc: cl@linux-foundation.org, mpm@selenic.com, linux-mm@kvack.org, akinobu.mita@gmail.com, linux-kernel@vger.kernel.org List-ID: On Fri, May 22, 2009 at 06:20:40PM +0930, Ron wrote: > > All other uses of kernel_map_pages() are explicitly excluded without > CONFIG_DEBUG_PAGEALLOC, this one should be too. > > Signed-off-by: Ron Lee > > > diff --git a/mm/slab.c b/mm/slab.c > index 9a90b00..b5e5b27 100644 > --- a/mm/slab.c > +++ b/mm/slab.c > @@ -2674,10 +2683,12 @@ static void cache_init_objs(struct kmem_cache *cachep, > slab_error(cachep, "constructor overwrote the" > " start of an object"); > } > +#ifdef CONFIG_DEBUG_PAGEALLOC > if ((cachep->buffer_size % PAGE_SIZE) == 0 && > OFF_SLAB(cachep) && cachep->flags & SLAB_POISON) > kernel_map_pages(virt_to_page(objp), > cachep->buffer_size / PAGE_SIZE, 0); > +#endif > #else > if (cachep->ctor) > cachep->ctor(objp); Actually, no. I'm wrong on this one. The compiler will already take that one away because kernel_map_pages() is an empty function in that case. It's subtle, but this extra guard actually adds nothing (unless you consider more #ifdefs to be 'clarifying'); Sorry for the extra noise, Ron -- 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