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From: Greg Thelen <gthelen@google.com>
Date: Thu, 10 Mar 2011 08:18:33 -0800
Message-ID: <AANLkTimuHeGMY0ELXgsn+BmAibvV34x3RvphF+3SODqw@mail.gmail.com>
Subject: Re: [PATCH v5 6/9] memcg: add kernel calls for memcg dirty page stats
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        containers@lists.osdl.org, Andrea Righi <arighi@develer.com>,
        Balbir Singh <balbir@linux.vnet.ibm.com>,
        Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>,
        Ciju Rajan K <ciju@linux.vnet.ibm.com>,
        David Rientjes <rientjes@google.com>,
        Wu Fengguang <fengguang.wu@intel.com>,
        Chad Talbott <ctalbott@google.com>,
        Justin TerAvest <teravest@google.com>, Vivek Goyal <vgoyal@redhat.com>
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On Sun, Feb 27, 2011 at 6:40 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@jp.fujitsu.com> wrote:
> On Mon, 28 Feb 2011 02:01:43 +0900
> Minchan Kim <minchan.kim@gmail.com> wrote:
>
>> On Fri, Feb 25, 2011 at 01:35:57PM -0800, Greg Thelen wrote:
> ? ? ? ? ? ? ? ?spin_unlock_irqrestore(&mapping->tree_lock, flags);
>> > ? ? } else {
>> > @@ -1365,6 +1368,7 @@ int test_set_page_writeback(struct page *page)
>> > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? PAGECACHE_TAG_WRITEBACK);
>> > ? ? ? ? ? ? ? ? ? ? if (bdi_cap_account_writeback(bdi))
>> > ? ? ? ? ? ? ? ? ? ? ? ? ? ? __inc_bdi_stat(bdi, BDI_WRITEBACK);
>> > + ? ? ? ? ? ? ? ? ? mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_WRITEBACK);
>>
>> Question:
>> Why should we care of BDI_CAP_NO_WRITEBACK?
>>
> Hmm, should we do ..
> ==
> ? ? ? ?if (!ret) {
> ? ? ? ? ? ? ? ?account_page_writeback(page);
> + ? ? ? ? ? ? ? mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_WRITEBACL);
> ? ? ? ?}
> ==

Yes, I agree with Minchan that this is an issue.  I think Kame's fix
is good.  I will apply Kame's fix to test_set_page_writeback().  I
also found that test_clear_page_writeback() has the same issue and it
will also be fixed.  I will be posting v6 shortly (hopefully today)
with these fixes.

> Thanks,
> -Kame
>
>
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