linux-kernel - Re: [PATCH v14 4/4] cgroup: implement the PIDs subsystem

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 for Android: free password hash cracker in your pocket

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

Date:	Wed, 10 Jun 2015 13:53:04 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Aleksa Sarai <cyphar@...har.com>
Cc:	lizefan@...wei.com, mingo@...hat.com, peterz@...radead.org,
	richard@....at, fweisbec@...il.com, linux-kernel@...r.kernel.org,
	cgroups@...r.kernel.org
Subject: Re: [PATCH v14 4/4] cgroup: implement the PIDs subsystem

On Tue, Jun 09, 2015 at 09:32:10PM +1000, Aleksa Sarai wrote:
> Adds a new single-purpose PIDs subsystem to limit the number of
> tasks that can be forked inside a cgroup. Essentially this is an
> implementation of RLIMIT_NPROC that applies to a cgroup rather than a
> process tree.
> 
> However, it should be noted that organisational operations (adding and
> removing tasks from a PIDs hierarchy) will *not* be prevented. Rather,
> the number of tasks in the hierarchy cannot exceed the limit through
> forking. This is due to the fact that, in the unified hierarchy, attach
> cannot fail (and it is not possible for a task to overcome its PIDs
> cgroup policy limit by attaching to a child cgroup -- even if migrating
> mid-fork it must be able to fork in the parent first).
> 
> PIDs are fundamentally a global resource, and it is possible to reach
> PID exhaustion inside a cgroup without hitting any reasonable kmemcg
> policy. Once you've hit PID exhaustion, you're only in a marginally
> better state than OOM. This subsystem allows PID exhaustion inside a
> cgroup to be prevented.

Patches 3-4 look good to me.  Will apply once v4.3 dev window opens.

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/