From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alex Shi <alex.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>
Subject: Re: [PATCH v17 14/21] mm/compaction: do page isolation first in
 compaction
Date: Fri, 7 Aug 2020 11:24:35 +0800
Message-ID: <241ca157-104f-4f0d-7d5b-de394443788d@linux.alibaba.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>
Mime-Version: 1.0
Content-Transfer-Encoding: 8bit
Return-path: <cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
In-Reply-To: <CAKgT0UcbBv=QBK9ErqLKXoNLYxFz52L4fiiHy4h6zKdBs=YPOg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
List-ID: <cgroups.vger.kernel.org>
Content-Type: text/plain; charset="utf-8"
To: Alexander Duyck <alexander.duyck-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Mel Gorman <mgorman-3eNAlZScCAx27rWaFMvyedHuzzzSOjJt@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Konstantin Khlebnikov <khlebnikov-XoJtRXgx1JseBXzfvpsJ4g@public.gmane.org>, Daniel Jordan <daniel.m.jordan-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>, Yang Shi <yang.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>, Matthew Wilcox <willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, kbuild test robot <lkp-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, linux-mm <linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>, LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Joonsoo Kim <iamjoonsoo.kim-Hm3cg6mZ9cc@public.gmane.org>, Wei Yang <richard.weiyang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, "Kirill A. Shutemov" <kirill-oKw7cIdHH8eLwutG50LtGA@public.gmane.org>, Rong Chen <rong.a.chen-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>



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