From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752249Ab1GZRl6 (ORCPT ); Tue, 26 Jul 2011 13:41:58 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:42621 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751211Ab1GZRlx (ORCPT ); Tue, 26 Jul 2011 13:41:53 -0400 X-Authority-Analysis: v=1.1 cv=sbbt6Wn8j+VvNVI1Ftt/uHhinWyuFt+R57MN9Ty2Tys= c=1 sm=0 a=Qv89JQfnOpAA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=meVymXHHAAAA:8 a=VwQbUJbxAAAA:8 a=W0vUJOdyAAAA:8 a=PqNd8jxuZCaroCJSvU4A:9 a=6d2kLKNEXrcqNgOZwuYA:7 a=PUjeQqilurYA:10 a=x8gzFH9gYPwA:10 a=jeBq3FmKZ4MA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Subject: Re: [PATCH] cgroup/kmemcheck: No need to annotate base anymore From: Steven Rostedt To: Michal Hocko Cc: LKML , Johannes Weiner , KAMEZAWA Hiroyuki , Daisuke Nishimura , Balbir Singh , Minchan Kim , Randy Dunlap , Andrew Morton , Dave Hansen , Catalin Marinas In-Reply-To: <20110726173816.GA26597@tiehlicka.suse.cz> References: <1311699911.3526.87.camel@gandalf.stny.rr.com> <20110726173816.GA26597@tiehlicka.suse.cz> Content-Type: text/plain; charset="ISO-8859-15" Date: Tue, 26 Jul 2011 13:41:50 -0400 Message-ID: <1311702110.3526.98.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.32.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2011-07-26 at 19:38 +0200, Michal Hocko wrote: > On Tue 26-07-11 13:05:11, Steven Rostedt wrote: > > When the cgroup base was allocated with kmalloc, it was necessary to > > annotate the variable with kmemcheck_not_leak(). But because it has > > recently been changed to be allocated with alloc_page(), the annotation > > is no longer needed. > > > > I was triggering this output: > > > > allocated 8388608 bytes of page_cgroup > > please try 'cgroup_disable=memory' option if you don't want memory cgroups > > kmemleak: Trying to color unknown object at 0xf5840000 as Grey > > Pid: 0, comm: swapper Not tainted 3.0.0-test #12 > > Call Trace: > > [] ? printk+0x1d/0x1f^M > > [] paint_ptr+0x4f/0x78 > > [] kmemleak_not_leak+0x58/0x7d > > [] ? __rcu_read_unlock+0x9/0x7d > > [] kmemleak_init+0x19d/0x1e9 > > [] start_kernel+0x346/0x3ec > > [] ? loglevel+0x18/0x18 > > [] i386_start_kernel+0xaa/0xb0 > > > > After a bit of debugging I tracked the object 0xf840000 (and others) > > down to the cgroup code. The change from allocating base with kmalloc to > > alloc_page() has the base not calling kmemleak_alloc() which adds the > > pointer to the object_tree_root, but kmemleak_not_leak() adds it to the > > crt_early_log[] table. On kmemleak_init(), the entry is found in the > > early_log[] but not the object_tree_root, and this error message is > > displayed. > > We can still fall back to vmalloc allocation (even though it is really > not probable that alloc_pages_exact_nid would fail that early). > Is vmalloc a problem here? (sorry I am not familiar with kmemleak > internals) The original code didn't distinguish kmalloc vs. vmalloc. > Good question. I forgot to add the maintainer of kmemleak to the Cc list. (fixed here). -- Steve > > > > Signed-off-by: Steven Rostedt > > > > diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c > > index 53bffc6..955a49f 100644 > > --- a/mm/page_cgroup.c > > +++ b/mm/page_cgroup.c > > @@ -9,7 +9,6 @@ > > #include > > #include > > #include > > -#include > > > > static void __meminit init_page_cgroup(struct page_cgroup *pc, unsigned long id) > > { > > @@ -179,13 +178,6 @@ static int __meminit init_section_page_cgroup(unsigned long pfn, int nid) > > table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION; > > base = alloc_page_cgroup(table_size, nid); > > > > - /* > > - * The value stored in section->page_cgroup is (base - pfn) > > - * and it does not point to the memory block allocated above, > > - * causing kmemleak false positives. > > - */ > > - kmemleak_not_leak(base); > > - > > if (!base) { > > printk(KERN_ERR "page cgroup allocation failure\n"); > > return -ENOMEM; > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ >