From mboxrd@z Thu Jan 1 00:00:00 1970 From: KAMEZAWA Hiroyuki Subject: [PATCH 3/12] memcg make root cgroup unlimited. Date: Thu, 25 Sep 2008 15:15:43 +0900 Message-ID: <20080925151543.ba307898.kamezawa.hiroyu@jp.fujitsu.com> References: <20080925151124.25898d22.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20080925151124.25898d22.kamezawa.hiroyu@jp.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "balbir@linux.vnet.ibm.com" , "nishimura@mxp.nes.nec.co.jp" , "xemul@openvz.org" , Andrew Morton , LKML , Dave Hansen , ryov@valinux.co.jp List-Id: linux-mm.kvack.org Make root cgroup of memory resource controller to have no limit. By this, users cannot set limit to root group. This is for making root cgroup as a kind of trash-can. For accounting pages which has no owner, which are created by force_empty, we need some cgroup with no_limit. A patch for rewriting force_empty will will follow this one. Signed-off-by: KAMEZAWA Hiroyuki Documentation/controllers/memory.txt | 4 ++++ mm/memcontrol.c | 7 +++++++ 2 files changed, 11 insertions(+) Index: mmotm-2.6.27-rc7+/mm/memcontrol.c =================================================================== --- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c +++ mmotm-2.6.27-rc7+/mm/memcontrol.c @@ -136,6 +136,9 @@ struct mem_cgroup { }; static struct mem_cgroup init_mem_cgroup; +#define is_root_cgroup(cgrp) ((cgrp) == &init_mem_cgroup) + + /* * We use the lower bit of the page->page_cgroup pointer as a bit spin * lock. We need to ensure that page->page_cgroup is at least two @@ -945,6 +948,10 @@ static int mem_cgroup_write(struct cgrou switch (cft->private) { case RES_LIMIT: + if (is_root_cgroup(memcg)) { + ret = -EINVAL; + break; + } /* This function does all necessary parse...reuse it */ ret = res_counter_memparse_write_strategy(buffer, &val); if (!ret) Index: mmotm-2.6.27-rc7+/Documentation/controllers/memory.txt =================================================================== --- mmotm-2.6.27-rc7+.orig/Documentation/controllers/memory.txt +++ mmotm-2.6.27-rc7+/Documentation/controllers/memory.txt @@ -121,6 +121,9 @@ The corresponding routines that remove a a page from Page Cache is used to decrement the accounting counters of the cgroup. +The root cgroup is not allowed to be set limit but usage is accounted. +For controlling usage of memory, you need to create a cgroup. + 2.3 Shared Page Accounting Shared pages are accounted on the basis of the first touch approach. The @@ -172,6 +175,7 @@ We can alter the memory limit: NOTE: We can use a suffix (k, K, m, M, g or G) to indicate values in kilo, mega or gigabytes. +Note: root cgroup is not able to be set limit. # cat /cgroups/0/memory.limit_in_bytes 4194304