linux-kernel - Re: [PATCH mmotm] memcg: fix mem_cgroup_update_mapped_file

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20090430045240.GA4430@balbir.in.ibm.com>
Date:	Thu, 30 Apr 2009 10:22:40 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Hugh Dickins <hugh@...itas.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH mmotm] memcg: fix mem_cgroup_update_mapped_file_stat
	oops

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> [2009-04-30 09:06:46]:

> On Wed, 29 Apr 2009 22:13:33 +0100 (BST)
> Hugh Dickins <hugh@...itas.com> wrote:
> 
> > CONFIG_SPARSEMEM=y CONFIG_CGROUP_MEM_RES_CTLR=y cgroup_disable=memory
> > bootup is oopsing in mem_cgroup_update_mapped_file_stat().  !SPARSEMEM
> > is fine because its lookup_page_cgroup() contains an explicit check for
> > NULL node_page_cgroup, but the SPARSEMEM version was missing a check for
> > NULL section->page_cgroup.
> > 
> Ouch, it's curious this bug alive now.. thank you.
> 
> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> 
> I think this patch itself is sane but.. Balbir, could you see "caller" ?
> It seems strange.

Ideally we need to have a disabled check in
mem_cgroup_update_mapped_file_stat(), but it seems as if this fix is
better and fixes a larger scenario and the root cause of
lookup_page_cgroup() OOPSing. It would not hurt to check for
mem_cgroup_disabled() though, but too many checks might spoil the
party for frequent operations.

Kame, do you mean you wanted me to check if I am using
lookup_page_cgroup() correctly?

Hugh, Thank you very much for finding and fixing the problem!
Acked-by: Balbir Singh <balbir@...ux.vnet.ibm.com>
 

-- 
	Balbir
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/