linux-kernel - Re: [PATCH 2/2] kernfs: do not account ino

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: <20150505160459.GA23654@esperanza>
Date:	Tue, 5 May 2015 19:04:59 +0300
From:	Vladimir Davydov <vdavydov@...allels.com>
To:	Tejun Heo <tj@...nel.org>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.cz>,
	Christoph Lameter <cl@...ux.com>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Greg Thelen <gthelen@...gle.com>, <linux-mm@...ck.org>,
	<cgroups@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] kernfs: do not account ino_ida allocations to memcg

On Tue, May 05, 2015 at 09:45:21AM -0400, Tejun Heo wrote:
> On Tue, May 05, 2015 at 12:45:43PM +0300, Vladimir Davydov wrote:
> > root->ino_ida is used for kernfs inode number allocations. Since IDA has
> > a layered structure, different IDs can reside on the same layer, which
> > is currently accounted to some memory cgroup. The problem is that each
> > kmem cache of a memory cgroup has its own directory on sysfs (under
> > /sys/fs/kernel/<cache-name>/cgroup). If the inode number of such a
> > directory or any file in it gets allocated from a layer accounted to the
> > cgroup which the cache is created for, the cgroup will get pinned for
> > good, because one has to free all kmem allocations accounted to a cgroup
> > in order to release it and destroy all its kmem caches. That said we
> > must not account layers of ino_ida to any memory cgroup.
> > 
> > Since per net init operations may create new sysfs entries directly
> > (e.g. lo device) or indirectly (nf_conntrack creates a new kmem cache
> > per each namespace, which, in turn, creates new sysfs entries), an easy
> > way to reproduce this issue is by creating network namespace(s) from
> > inside a kmem-active memory cgroup.
> > 
> > Signed-off-by: Vladimir Davydov <vdavydov@...allels.com>
> 
> Man, that's nasty.  For the kernfs part,
> 
> Acked-by: Tejun Heo <tj@...nel.org>

Thanks.

> 
> Can you please repost this patch w/ Greg KH cc'd?

OK.
--
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/