From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964879AbaH0PcU (ORCPT ); Wed, 27 Aug 2014 11:32:20 -0400 Received: from qmta08.emeryville.ca.mail.comcast.net ([76.96.30.80]:42144 "EHLO qmta08.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964866AbaH0PcO (ORCPT ); Wed, 27 Aug 2014 11:32:14 -0400 Date: Wed, 27 Aug 2014 10:32:11 -0500 (CDT) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: WANG Chao cc: Andrew Morton , Pekka Enberg , David Rientjes , Joonsoo Kim , "open list:SLAB ALLOCATOR" , open list Subject: Re: [PATCH] mm, slub: do not add duplicate sysfs In-Reply-To: Message-ID: References: <1409152488-21227-1-git-send-email-chaowang@redhat.com> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Maybe something like this may be a proper fix: Subject: slub: Disable tracing of mergeable slabs Tracing of mergeable slabs is confusing since the objects of multiple slab caches will be traced. Moreover this creates a situation where a mergeable slab will become unmergeable. If tracing is desired then it may be best to switch merging off for starters. Signed-off-by: Christoph Lameter Index: linux/mm/slub.c =================================================================== --- linux.orig/mm/slub.c 2014-08-08 11:52:30.039681592 -0500 +++ linux/mm/slub.c 2014-08-27 10:30:16.508108726 -0500 @@ -4604,6 +4604,14 @@ static ssize_t trace_show(struct kmem_ca static ssize_t trace_store(struct kmem_cache *s, const char *buf, size_t length) { + /* + * Tracing a merged cache is going to give confusing results + * as well as cause other issues like converting a mergeable + * cache into an umergeable one. + */ + if (s->refcount > 1) + return -EINVAL; + s->flags &= ~SLAB_TRACE; if (buf[0] == '1') { s->flags &= ~__CMPXCHG_DOUBLE;