Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v17 14/21] mm/compaction: do page isolation first in
 compaction
To:     Alexander Duyck <alexander.duyck@gmail.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@techsingularity.net>,
        Tejun Heo <tj@kernel.org>, Hugh Dickins <hughd@google.com>,
        Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        Daniel Jordan <daniel.m.jordan@oracle.com>,
        Yang Shi <yang.shi@linux.alibaba.com>,
        Matthew Wilcox <willy@infradead.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        kbuild test robot <lkp@intel.com>,
        linux-mm <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>, cgroups@vger.kernel.org,
        Shakeel Butt <shakeelb@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Wei Yang <richard.weiyang@gmail.com>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        Rong Chen <rong.a.chen@intel.com>
References: <1595681998-19193-1-git-send-email-alex.shi@linux.alibaba.com>
 <1595681998-19193-15-git-send-email-alex.shi@linux.alibaba.com>
 <CAKgT0UcbBv=QBK9ErqLKXoNLYxFz52L4fiiHy4h6zKdBs=YPOg@mail.gmail.com>
 <241ca157-104f-4f0d-7d5b-de394443788d@linux.alibaba.com>
 <CAKgT0UdSrarC8j+G=LYRSadcaG6yNCoCfeVpFjEiHRJb4A77-g@mail.gmail.com>
From:   Alex Shi <alex.shi@linux.alibaba.com>
Message-ID: <8dbd004e-8eba-f1ec-a5eb-5dc551978936@linux.alibaba.com>
Date:   Mon, 10 Aug 2020 21:10:17 +0800
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0)
 Gecko/20100101 Thunderbird/68.7.0
MIME-Version: 1.0
In-Reply-To: <CAKgT0UdSrarC8j+G=LYRSadcaG6yNCoCfeVpFjEiHRJb4A77-g@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


在 2020/8/7 下午10:51, Alexander Duyck 写道:
> I wonder if this entire section shouldn't be restructured. This is the
> only spot I can see where we are resetting the LRU flag instead of
> pulling the page from the LRU list with the lock held. Looking over
> the code it seems like something like that should be possible. I am
> not sure the LRU lock is really protecting us in either the
> PageCompound check nor the skip bits. It seems like holding a
> reference on the page should prevent it from switching between
> compound or not, and the skip bits are per pageblock with the LRU bits
> being per node/memcg which I would think implies that we could have
> multiple LRU locks that could apply to a single skip bit.

Hi Alexander,

I don't find problem yet on compound or skip bit usage. Would you clarify the
issue do you concerned? 

Thanks!