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  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]
Date:	Thu, 3 Apr 2014 15:43:35 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	David Miller <davem@...emloft.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Li Zefan <lizefan@...wei.com>,
	Linux Containers <containers@...ts.linux-foundation.org>,
	cgroups@...r.kernel.org
Subject: Re: [GIT PULL] cgroup changes for v3.15-rc1

Hello,

On Thu, Apr 03, 2014 at 12:01:23PM -0700, Linus Torvalds wrote:
> [ Extending the participants list a bit ]
> 
> On Thu, Apr 3, 2014 at 11:34 AM, Tejun Heo <tj@...nel.org> wrote:
> > On the road so sending from phone. Iirc the param is necessary to
> > distinguishe when a new sb is created so that it can be put properly later.
> > I think cgroup is leaking super ref now and li was planning to send a fix
> > once things are merged.
> 
> So as far as I can tell, cgroup is fine, because the superblock itself
> is properly refcounted by the mounting code. It's the magic hidden

Ah, I remembered the other way around.  We could leak cgroup_root
reference, not the other way around.  cgroup_mount() can be called
multiple times for the same sb and we inc cgroup_root's ref each time
but cgroup_kill_sb() only happens when the sb is released, so if we do
the following,

 # mkdir cpuset cpuset1
 # mount -t cgroup -o cpuset cgroup cpuset
 # mount -t cgroup -o cpuset cgroup cpuset1
 # umount cpuset
 # umount cpuset1

The cgroup_root should be destroyed but it isn't, I think.  We'd need
to bump cgroup_root's refcnt only when a new sb is created.  It's
kinda ugly.  Hmmm...

As for using specific type for ns tag, yeah, that'd be better
regardless of this.  The opaqueness is a bit extreme now.

Thanks.

-- 
tejun
--
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/

Powered by blists - more mailing lists