From: Michal Hocko <mhocko@suse.cz>
To: Sha Zhengju <handai.szj@gmail.com>
Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
akpm@linux-foundation.org, kamezawa.hiroyu@jp.fujitsu.com,
gthelen@google.com, fengguang.wu@intel.com,
glommer@parallels.com, dchinner@redhat.com,
Sha Zhengju <handai.szj@taobao.com>
Subject: Re: [PATCH V3 4/8] memcg: add per cgroup dirty pages accounting
Date: Fri, 3 May 2013 11:11:49 +0200 [thread overview]
Message-ID: <20130503091149.GA17496@dhcp22.suse.cz> (raw)
In-Reply-To: <20130102104421.GC22160@dhcp22.suse.cz>
On Wed 02-01-13 11:44:21, Michal Hocko wrote:
> On Wed 26-12-12 01:26:07, Sha Zhengju wrote:
> > From: Sha Zhengju <handai.szj@taobao.com>
> >
> > This patch adds memcg routines to count dirty pages, which allows memory controller
> > to maintain an accurate view of the amount of its dirty memory and can provide some
> > info for users while cgroup's direct reclaim is working.
>
> I guess you meant targeted resp. (hard/soft) limit reclaim here,
> right? It is true that this is direct reclaim but it is not clear to me
> why the usefulnes should be limitted to the reclaim for users. I would
> understand this if the users was in fact in-kernel users.
>
> [...]
> > To prevent AB/BA deadlock mentioned by Greg Thelen in previous version
> > (https://lkml.org/lkml/2012/7/30/227), we adjust the lock order:
> > ->private_lock --> mapping->tree_lock --> memcg->move_lock.
> > So we need to make mapping->tree_lock ahead of TestSetPageDirty in __set_page_dirty()
> > and __set_page_dirty_nobuffers(). But in order to avoiding useless spinlock contention,
> > a prepare PageDirty() checking is added.
>
> But there is another AA deadlock here I believe.
> page_remove_rmap
> mem_cgroup_begin_update_page_stat <<< 1
> set_page_dirty
> __set_page_dirty_buffers
> __set_page_dirty
> mem_cgroup_begin_update_page_stat <<< 2
> move_lock_mem_cgroup
> spin_lock_irqsave(&memcg->move_lock, *flags);
JFYI since abf09bed (s390/mm: implement software dirty bits) this is no
longer possible. I haven't checked wheter there are other cases like
this one and it should be better if mem_cgroup_begin_update_page_stat
was recursive safe if that can be done without too many hacks.
I will have a look at this (hopefully) sometimes next week.
[...]
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2013-05-03 9:11 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-25 17:18 [PATCH V3 0/8] Per-cgroup page stat accounting Sha Zhengju
2012-12-25 17:20 ` [PATCH V3 1/8] memcg: remove MEMCG_NR_FILE_MAPPED Sha Zhengju
2012-12-25 17:22 ` [PATCH V3 2/8] Make TestSetPageDirty and dirty page accounting in one func Sha Zhengju
2012-12-28 0:39 ` Kamezawa Hiroyuki
2013-01-05 2:34 ` Sha Zhengju
2013-01-02 9:08 ` Michal Hocko
2013-01-05 2:49 ` Sha Zhengju
2013-01-05 10:45 ` Michal Hocko
2012-12-25 17:24 ` [PATCH V3 3/8] use vfs __set_page_dirty interface instead of doing it inside filesystem Sha Zhengju
2012-12-28 0:41 ` Kamezawa Hiroyuki
2012-12-25 17:26 ` [PATCH V3 4/8] memcg: add per cgroup dirty pages accounting Sha Zhengju
2013-01-02 10:44 ` Michal Hocko
2013-01-05 4:48 ` Sha Zhengju
2013-01-06 20:02 ` Hugh Dickins
2013-01-07 7:49 ` Kamezawa Hiroyuki
2013-01-09 5:15 ` Hugh Dickins
2013-01-09 7:24 ` Kamezawa Hiroyuki
2013-01-09 14:35 ` Sha Zhengju
2013-01-09 14:47 ` Michal Hocko
2013-01-07 7:25 ` Kamezawa Hiroyuki
2013-01-09 15:02 ` Sha Zhengju
2013-01-10 2:16 ` Kamezawa Hiroyuki
2013-01-10 4:26 ` Sha Zhengju
2013-01-10 5:03 ` Kamezawa Hiroyuki
2013-01-10 8:28 ` Sha Zhengju
2013-05-03 9:11 ` Michal Hocko [this message]
2013-05-03 9:59 ` Sha Zhengju
2013-01-06 20:07 ` Greg Thelen
2013-01-09 9:45 ` Sha Zhengju
2012-12-25 17:26 ` [PATCH V3 5/8] memcg: add per cgroup writeback " Sha Zhengju
2012-12-28 0:52 ` Kamezawa Hiroyuki
2013-01-02 11:15 ` Michal Hocko
2013-01-06 20:07 ` Greg Thelen
2013-01-09 9:08 ` Sha Zhengju
2012-12-25 17:27 ` [PATCH V3 6/8] memcg: Don't account root_mem_cgroup page statistics Sha Zhengju
2012-12-28 1:04 ` Kamezawa Hiroyuki
2013-01-05 7:38 ` Sha Zhengju
2013-01-02 12:27 ` Michal Hocko
2013-01-05 10:52 ` Sha Zhengju
2013-01-09 12:57 ` Michal Hocko
2012-12-25 17:27 ` [PATCH V3 7/8] memcg: disable memcg page stat accounting code when not in use Sha Zhengju
2012-12-28 1:06 ` Kamezawa Hiroyuki
2012-12-28 1:45 ` Kamezawa Hiroyuki
2013-01-05 11:06 ` Sha Zhengju
2013-01-02 13:35 ` Michal Hocko
2012-12-25 17:28 ` [PATCH V3 8/8] memcg: Document cgroup dirty/writeback memory statistics Sha Zhengju
2012-12-28 1:10 ` Kamezawa Hiroyuki
2013-01-06 2:55 ` Sha Zhengju
2013-01-02 13:36 ` Michal Hocko
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