linux-kernel - Re: [PATCH 2/2] cgroup: make css->refcnt clearing on cgroup removal optional

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]

Date:	Sun, 1 Apr 2012 15:48:23 -0400
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	Li Zefan <lizefan@...wei.com>,
	containers@...ts.linux-foundation.org, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org, fweisbec@...il.com, rni@...gle.com,
	ctalbott@...gle.com, Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.cz>,
	Balbir Singh <bsingharora@...il.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [PATCH 2/2] cgroup: make css->refcnt clearing on cgroup removal
 optional

On Fri, Mar 30, 2012 at 03:36:06PM -0700, Tejun Heo wrote:
> Currently, cgroup removal tries to drain all css references.  If there
> are active css references, the removal logic waits and retries
> ->pre_detroy() until either all refs drop to zero or removal is
> cancelled.
> 
> This semantics is unusual and adds non-trivial complexity to cgroup
> core and IMHO is fundamentally misguided in that it couples internal
> implementation details (references to internal data structure) with
> externally visible operation (rmdir).  To userland, this is a behavior
> peculiarity which is unnecessary and difficult to expect (css refs is
> otherwise invisible from userland), and, to policy implementations,
> this is an unnecessary restriction (e.g. blkcg wants to hold css refs
> for caching purposes but can't as that becomes visible as rmdir hang).

Good to see this patch. Now annyoying rmdir hang with blkcg should be
gone.

Thanks
Vivek
--
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/