From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [PATCH 00/10] cgroups: Task counter subsystem v8 Date: Mon, 05 Mar 2012 11:44:28 -0500 Message-ID: <4F54ED6C.4060600@redhat.com> References: <1328067470-5980-1-git-send-email-fweisbec@gmail.com> <20120201163126.GA19837@google.com> <20120201184959.GH6731@somewhere.redhat.com> <20120201115107.93e11471.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120201115107.93e11471.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> 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: Andrew Morton Cc: Aditya Kali , Glauber Costa , "Daniel P. Berrange" , Max Kellermann , Tim Hockin , Frederic Weisbecker , Paul Menage , Daniel J Walsh , LKML , Oleg Nesterov , Mandeep Singh Baines , Cgroups , Johannes Weiner , Tejun Heo , Containers List-Id: containers.vger.kernel.org On 02/01/2012 02:51 PM, Andrew Morton wrote: > On Wed, 1 Feb 2012 19:50:01 +0100 > Frederic Weisbecker wrote: > >> On Wed, Feb 01, 2012 at 08:31:26AM -0800, Tejun Heo wrote: >>> On Wed, Feb 01, 2012 at 04:37:40AM +0100, Frederic Weisbecker wrote: >>>> Changes In this version: >>>> >>>> - Split 32/64 bits version of res_counter_write_u64() [1/10] >>>> Courtesy of Kirill A. Shutemov >>>> >>>> - Added Kirill's ack [8/10] >>>> >>>> - Added selftests [9/10], [10/10] >>>> >>>> Please consider for merging. At least two users want this feature: >>> >>> Has there been further discussion about this approach? IIRC, we >>> weren't sure whether this should be merged. >> >> The doubts I have noticed were: >> >> Q: Can't we rather focus on a global solution to fight forkbombs? >> >> If we can find a reliable solution that works in any case and that >> prevent from any forkbomb to impact the rest of the system then it >> may be an acceptable solution. But I'm not aware of such feature. >> >> Besides, another point in having this task counter is that we >> have a per container limit. Assuming all containers are running under >> the same user, we can protect against a container starving all others >> with a massive amount of processes close to the NR_PROC rlimit. > What I struggle with is "is this feature useful enough to warrant > merging it"? I have seen thunderbird create as many child processes as it could (until I hit my rlimit NR_PROC), and have seen web servers go wrong under a combination of load and buggy scripts, forking as many processes as they could. Since we know rlimit NR_PROC is useful, having the equivalent per cgroup will be useful, too. What we need to lose is the focus on malicious forkbombs - buggy programs are a real issue, and protecting against them is useful.