From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alex Shi <alex.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>
Subject: Re: [RFC PATCH v2 5/5] mm: Split move_pages_to_lru into 3 separate
 passes
Date: Thu, 20 Aug 2020 17:56:36 +0800
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To: Alexander Duyck <alexander.duyck-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Yang Shi <yang.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>, kbuild test robot <lkp-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Rong Chen <rong.a.chen-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Konstantin Khlebnikov <khlebnikov-XoJtRXgx1JseBXzfvpsJ4g@public.gmane.org>, "Kirill A. Shutemov" <kirill-oKw7cIdHH8eLwutG50LtGA@public.gmane.org>, Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Daniel Jordan <daniel.m.jordan-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>, linux-mm <linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>, Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Matthew Wilcox <willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Wei Yang <richard.weiyang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Mel Gorman <mgorman-3eNAlZScCAx27rWaFMvyedHuzzzSOjJt@public.gmane.org>, Joonsoo Kim <iamjoonsoo.kim-Hm3cg6mZ9cc@public.gmane.org>



在 2020/8/19 下午10:42, Alexander Duyck 写道:
>> It's actually changed the meaning from current func. which I had seen a bug if no relock.
>> but after move to 5.9 kernel, I can not reprodce the bug any more. I am not sure if 5.9 fixed
>> the problem, and we don't need relock here.
> So I am not sure what you mean here about "changed the meaning from
> the current func". Which function are you referring to and what
> changed?
> 
> From what I can tell the pages cannot change memcg because they were
> isolated and had the LRU flag stripped. They shouldn't be able to
> change destination LRU vector as a result. Assuming that, then they
> can all be processed under same LRU lock and we can avoid having to
> release it until we are forced to do so to call putback_lru_page or
> destroy the compound pages that were freed while we were shrinking the
> LRU lists.
> 

I had sent a bug which base on 5.8 kernel.
https://lkml.org/lkml/2020/7/28/465

I am not sure it was fixed in new kernel. The original line was introduced by Hugh Dickins
I believe it would be great if you can get comments from him.

Thanks
Alex