From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 589286B003D for ; Thu, 26 Mar 2009 01:08:57 -0400 (EDT) Date: Thu, 26 Mar 2009 14:51:48 +0900 From: Daisuke Nishimura Subject: Re: [RFC][BUGFIX][PATCH] memcg: fix shrink_usage Message-Id: <20090326145148.ba722e1e.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20090326141246.32305fe5.kamezawa.hiroyu@jp.fujitsu.com> References: <20090326130821.40c26cf1.nishimura@mxp.nes.nec.co.jp> <20090326141246.32305fe5.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: nishimura@mxp.nes.nec.co.jp, linux-mm , Balbir Singh , Li Zefan , Hugh Dickins List-ID: On Thu, 26 Mar 2009 14:12:46 +0900, KAMEZAWA Hiroyuki wrote: > On Thu, 26 Mar 2009 13:08:21 +0900 > Daisuke Nishimura wrote: > > > This is another bug I've working on recently. > > > > I want this (and the stale swapcache problem) to be fixed for 2.6.30. > > > > Any comments? > > > > === > > From: Daisuke Nishimura > > > > Current mem_cgroup_shrink_usage has two problems. > > > > 1. It doesn't call mem_cgroup_out_of_memory and doesn't update last_oom_jiffies, > > so pagefault_out_of_memory invokes global OOM. > > 2. Considering hierarchy, shrinking has to be done from the mem_over_limit, > > not from the memcg where the page to be charged to. > > > > Ah, i see. good cacth. > But it seems to be the patch is a bit big and includes duplications. > Can't we divide this patch into 2 and reduce modification ? > Will do if needed. (returning mem_over_limit part and implementing add_to_page_cache_store_memcg part, perhaps) > mem_cgroup_shrink_usage() should do something proper... > My brief thinking is a patch like this, how do you think ? > I thought the same direction at first. But it's similar to the old implementation before c9b0ed51 conceptually, so I chose a new direction. I withdraw my patch if you prefer this direction :) > Maybe renaming this function is appropriate... I think so too if we go in this direction. Just a few comments below. > == > mem_cgroup_shrink_usage() is called by shmem, but its purpose is > not different from try_charge(). > > In current behavior, it ignores upward hierarchy and doesn't update > OOM status of memcg. That's bad. We can simply call try_charge() > and drop charge later. > > Reported-by: Daisuke Nishimura > Signed-off-by: KAMEZAWA Hiroyuki > --- > mm/memcontrol.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > Index: test/mm/memcontrol.c > =================================================================== > --- test.orig/mm/memcontrol.c > +++ test/mm/memcontrol.c > @@ -1655,16 +1655,16 @@ int mem_cgroup_shrink_usage(struct page > if (unlikely(!mem)) > return 0; > > - do { > - progress = mem_cgroup_hierarchical_reclaim(mem, > - gfp_mask, true, false); > - progress += mem_cgroup_check_under_limit(mem); > - } while (!progress && --retry); > + ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, mem, true); > I think we should simply call mem_cgroup_try_charge_swapin() w/o doing try_get. > + if (!ret) { > + css_put(&mem->css); /* refcnt by charge *// It should be done after res_counter_uncharge(). > + res_counter_uncharge(&mem->res, PAGE_SIZE); > + if (do_swap_account) > + res_counter_uncharge(&mem->memsw, PAGE_SIZE); > + } > css_put(&mem->css); This put isn't needed if we don't try_get. > - if (!retry) > - return -ENOMEM; > - return 0; > + return ret; > } > > static DEFINE_MUTEX(set_limit_mutex); > Thanks, Daisuke Nishimura. -- 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