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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>,
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        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>,
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        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>
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From:   Alex Shi <alex.shi@linux.alibaba.com>
Message-ID: <241ca157-104f-4f0d-7d5b-de394443788d@linux.alibaba.com>
Date:   Fri, 7 Aug 2020 11:24:35 +0800
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在 2020/8/7 上午2:38, Alexander Duyck 写道:
>> +
>>  isolate_abort:
>>         if (locked)
>>                 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
>> +       if (page) {
>> +               SetPageLRU(page);
>> +               put_page(page);
>> +       }
>>
>>         /*
>>          * Updated the cached scanner pfn once the pageblock has been scanned
> We should probably be calling SetPageLRU before we release the lru
> lock instead of before. It might make sense to just call it before we
> get here, similar to how you did in the isolate_fail_put case a few
> lines later. Otherwise this seems to violate the rules you had set up
> earlier where we were only going to be setting the LRU bit while
> holding the LRU lock.

Hi Alex,

Set out of lock here should be fine. I never said we must set the bit in locking.
And this page is get by get_page_unless_zero(), no warry on release.

Thanks
Alex