linux-kernel - Re: [PATCH 2/3] memcg: Limit the number of events registered on oom

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Message-ID: <20130807140103.GH27006@htj.dyndns.org>
Date:	Wed, 7 Aug 2013 10:01:03 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	cgroups@...r.kernel.org, Johannes Weiner <hannes@...xchg.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Anton Vorontsov <anton.vorontsov@...aro.org>
Subject: Re: [PATCH 2/3] memcg: Limit the number of events registered on
 oom_control

On Wed, Aug 07, 2013 at 03:57:34PM +0200, Michal Hocko wrote:
> On Wed 07-08-13 09:47:41, Tejun Heo wrote:
> > Hello,
> > 
> > On Wed, Aug 07, 2013 at 03:37:46PM +0200, Michal Hocko wrote:
> > > > It isn't different from listening from epoll, for example.
> > > 
> > > epoll limits the number of watchers, no?
> > 
> > Not that I know of.  It'll be limited by max open fds but I don't
> > think there are other limits. 
> 
> max_user_watches seems to be a limit (4% of lowmem in maximum).

That's per *user* not per event source.  The problem here is creating
a global (across securit domains) resource shared by all users.

-- 
tejun
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