From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx141.postini.com [74.125.245.141]) by kanga.kvack.org (Postfix) with SMTP id 3D3A96B00E5 for ; Wed, 7 Aug 2013 09:47:46 -0400 (EDT) Received: by mail-vb0-f43.google.com with SMTP id h11so1814397vbh.2 for ; Wed, 07 Aug 2013 06:47:45 -0700 (PDT) Date: Wed, 7 Aug 2013 09:47:41 -0400 From: Tejun Heo Subject: Re: [PATCH 2/3] memcg: Limit the number of events registered on oom_control Message-ID: <20130807134741.GF27006@htj.dyndns.org> References: <1375874907-22013-1-git-send-email-mhocko@suse.cz> <1375874907-22013-2-git-send-email-mhocko@suse.cz> <20130807130836.GB27006@htj.dyndns.org> <20130807133746.GI8184@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130807133746.GI8184@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Johannes Weiner , KAMEZAWA Hiroyuki , Andrew Morton , "Kirill A. Shutemov" , Anton Vorontsov 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. Why would there be? > > If there needs to be kernel memory limit, shouldn't that be handled by > > kmemcg? > > kmemcg would surely help but turning it on just because of potential > abuse of the event registration API sounds like an overkill. > > I think having a cap for user trigable kernel resources is a good thing > in general. I don't know. It's just very arbitrary because listening to events itself isn't (and shouldn't) be something which consumes resource which isn't attributed to the listener and this artificially creates a global resource. The problem with memory usage event is breaching that rule with shared kmalloc() so putting well-defined limit on it is fine but the latter two create additional artificial restrictions which are both unnecessary and unconventional. No? Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org