From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Subject: Re: [PATCH 11/11] blkcg: implement per-blkg request allocation Date: Fri, 27 Apr 2012 12:19:59 -0400 Message-ID: <20120427161959.GL10579@redhat.com> References: <1335477561-11131-1-git-send-email-tj@kernel.org> <1335477561-11131-12-git-send-email-tj@kernel.org> <20120427150217.GK27486@google.com> <20120427154033.GJ10579@redhat.com> <20120427154502.GM27486@google.com> <20120427154841.GA16237@redhat.com> <20120427155140.GN27486@google.com> <20120427155612.GK10579@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20120427155612.GK10579-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Tejun Heo Cc: axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, ctalbott-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, rni-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jeff Moyer , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org On Fri, Apr 27, 2012 at 11:56:12AM -0400, Vivek Goyal wrote: > On Fri, Apr 27, 2012 at 08:51:40AM -0700, Tejun Heo wrote: > > On Fri, Apr 27, 2012 at 11:48:41AM -0400, Vivek Goyal wrote: > > > Not an unpriviliged malicious application. In typical cgroup scenario, we > > > can allow unpriviliged users to create child cgroups so that it can > > > further subdivide its resources to its children group. (ex. put firefox > > > in one cgroup, open office in another group etc.). > > > > > > So it is not same as jack up nr_requests. > > > > I find allowing unpriv users creating cgroups dumb. cgroup consumes > > kernel memory. Sans using kmemcg, what prevents them from creating > > gazillion cgroups and consuming all memories? The idea of allowing > > cgroups to !priv users is just broken from the get go. > > Well creating a task consumes memory too but we allow unpriv users to > create tasks. :-) Well, kernel can kill tasks and reclaim that memory so this is not an appropriate example. A more suitable example probably is AIO where kernel pins down some memory and we limit that amount by upper limit on number of aio requests. Thanks Vivek