linux-kernel - Re: [PATCH v17 14/21] mm/compaction: do page isolation first in compaction

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Message-ID: <51249892-632b-4aaf-1f66-3bc0d5c5cbab@linux.alibaba.com>
Date:   Wed, 12 Aug 2020 20:16:06 +0800
From:   Alex Shi <alex.shi@...ux.alibaba.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Tejun Heo <tj@...nel.org>, Hugh Dickins <hughd@...gle.com>,
        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        Yang Shi <yang.shi@...ux.alibaba.com>,
        Matthew Wilcox <willy@...radead.org>,
        Johannes Weiner <hannes@...xchg.org>,
        kbuild test robot <lkp@...el.com>,
        linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>, cgroups@...r.kernel.org,
        Shakeel Butt <shakeelb@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Wei Yang <richard.weiyang@...il.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Rong Chen <rong.a.chen@...el.com>
Subject: Re: [PATCH v17 14/21] mm/compaction: do page isolation first in
 compaction



在 2020/8/12 下午7:43, Alex Shi 写道:
>>> Sorry, I still can not follow you here. Compound code part is unchanged
>>> and follow the original logical. So would you like to pose a new code to
>>> see if its works?
>> No there are significant changes as you reordered all of the
>> operations. Prior to your change the LRU bit was checked, but not
>> cleared before testing for PageCompound. Now you are clearing it
>> before you are testing if it is a compound page. So if compaction is
>> running we will be seeing the pages in the LRU stay put, but the
>> compound bit flickering off and on if the compound page is encountered
>> with the wrong or NULL lruvec. What I was suggesting is that the

> The lruvec could be wrong or NULL here, that is the base stone of whole
> patchset.
> 
Sorry for typo. s/could/could not/