From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755349AbcBDIbX (ORCPT ); Thu, 4 Feb 2016 03:31:23 -0500 Received: from e06smtp07.uk.ibm.com ([195.75.94.103]:53234 "EHLO e06smtp07.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754344AbcBDIbV (ORCPT ); Thu, 4 Feb 2016 03:31:21 -0500 X-IBM-Helo: d06dlp03.portsmouth.uk.ibm.com X-IBM-MailFrom: borntraeger@de.ibm.com X-IBM-RcptTo: linux-api@vger.kernel.org;linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/5] mm/slub: query dynamic DEBUG_PAGEALLOC setting To: Joonsoo Kim , Andrew Morton References: <1454565386-10489-1-git-send-email-iamjoonsoo.kim@lge.com> <1454565386-10489-3-git-send-email-iamjoonsoo.kim@lge.com> Cc: David Rientjes , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Benjamin Herrenschmidt , Takashi Iwai , Chris Metcalf , Christoph Lameter , linux-api@vger.kernel.org, Joonsoo Kim From: Christian Borntraeger Message-ID: <56B30C52.7040907@de.ibm.com> Date: Thu, 4 Feb 2016 09:31:14 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 MIME-Version: 1.0 In-Reply-To: <1454565386-10489-3-git-send-email-iamjoonsoo.kim@lge.com> Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16020408-0029-0000-0000-000005B110D6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/04/2016 06:56 AM, Joonsoo Kim wrote: > We can disable debug_pagealloc processing even if the code is complied > with CONFIG_DEBUG_PAGEALLOC. This patch changes the code to query > whether it is enabled or not in runtime. > > Signed-off-by: Joonsoo Kim > --- > mm/slub.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 7d4da68..7b5a965 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -256,11 +256,12 @@ static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) > { > void *p; > > -#ifdef CONFIG_DEBUG_PAGEALLOC > - probe_kernel_read(&p, (void **)(object + s->offset), sizeof(p)); > -#else > - p = get_freepointer(s, object); > -#endif > + if (debug_pagealloc_enabled()) { > + probe_kernel_read(&p, > + (void **)(object + s->offset), sizeof(p)); Hmm, this might be a good case for a line longer than 80 chars.... As an alternative revert the logic and return early: if (!debug_pagealloc_enabled()) return get_freepointer(s, object); probe_kernel_read(&p, (void **)(object + s->offset), sizeof(p)); return p; ? > + } else > + p = get_freepointer(s, object); > + > return p; > } >