linux-kernel - Re: [PATCH v6 02/10] mm/lru: replace pgdat lru

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Message-ID: <a7b5c7bb-022f-60de-2d61-696915df002a@linux.alibaba.com>
Date:   Tue, 17 Dec 2019 21:11:18 +0800
From:   Alex Shi <alex.shi@...ux.alibaba.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, akpm@...ux-foundation.org,
        mgorman@...hsingularity.net, tj@...nel.org, hughd@...gle.com,
        khlebnikov@...dex-team.ru, daniel.m.jordan@...cle.com,
        yang.shi@...ux.alibaba.com, shakeelb@...gle.com,
        hannes@...xchg.org, Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Roman Gushchin <guro@...com>,
        Chris Down <chris@...isdown.name>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vlastimil Babka <vbabka@...e.cz>, Qian Cai <cai@....pw>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        David Rientjes <rientjes@...gle.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        swkhack <swkhack@...il.com>,
        "Potyra, Stefan" <Stefan.Potyra@...ktrobit.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Colin Ian King <colin.king@...onical.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Peng Fan <peng.fan@....com>,
        Nikolay Borisov <nborisov@...e.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Yafang Shao <laoar.shao@...il.com>
Subject: Re: [PATCH v6 02/10] mm/lru: replace pgdat lru_lock with lruvec lock



在 2019/12/17 上午10:16, Matthew Wilcox 写道:
>>> You still didn't fix this function.  Go back and look at my comment from
>>> the last time you sent this patch set.
>>>
>> Sorry for the misunderstanding. I guess what your want is fold the patch 9th into this, is that right?
>> Any comments for the 9th patch?
> I didn't get as far as looking at the ninth patch because I saw this
> one was wrong and stopped looking.  This is not the first time *with
> this patch set* that you've been told to *fix the patch*, not submit
> something that's broken and fix it in a later patch.
> 
> I'll look at patch 9 later.


Thanks a lot for the nice cocaching and quick response!

What the problem for me here is I didn't find a bug here. From the commit_charge's explanations and mem_cgroup_commit_charge comments, as well as call path when lrucare is ture, The lock is just to guard the task migration(which would be lead to move_account) So, It's just a clean up to give up locking when !PageLRU in patch 9. And even w/o patch 9, the page just locked root_mem_cgroup's lru_lock, same as old function does, while the page isn't on any LRU. Useless, but it's still safe.

Do you mind to point out anything else I missed?

Thanks a lot!
Alex