linux-kernel - Re: [PATCH v20 13/20] mm/mlock: remove lru

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Date:   Mon, 2 Nov 2020 09:55:00 -0500
From:   Johannes Weiner <hannes@...xchg.org>
To:     Alex Shi <alex.shi@...ux.alibaba.com>
Cc:     akpm@...ux-foundation.org, mgorman@...hsingularity.net,
        tj@...nel.org, hughd@...gle.com, khlebnikov@...dex-team.ru,
        daniel.m.jordan@...cle.com, willy@...radead.org, lkp@...el.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        cgroups@...r.kernel.org, shakeelb@...gle.com,
        iamjoonsoo.kim@....com, richard.weiyang@...il.com,
        kirill@...temov.name, alexander.duyck@...il.com,
        rong.a.chen@...el.com, mhocko@...e.com, vdavydov.dev@...il.com,
        shy828301@...il.com,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [PATCH v20 13/20] mm/mlock: remove lru_lock on
 TestClearPageMlocked

On Thu, Oct 29, 2020 at 06:44:58PM +0800, Alex Shi wrote:
> In the func munlock_vma_page, comments mentained lru_lock needed for
> serialization with split_huge_pages. But the page must be PageLocked
> as well as pages in split_huge_page series funcs. Thus the PageLocked
> is enough to serialize both funcs.
> 
> Further more, Hugh Dickins pointed: before splitting in
> split_huge_page_to_list, the page was unmap_page() to remove pmd/ptes
> which protect the page from munlock. Thus, no needs to guard
> __split_huge_page_tail for mlock clean, just keep the lru_lock there for
> isolation purpose.
> 
> LKP found a preempt issue on __mod_zone_page_state which need change
> to mod_zone_page_state. Thanks!
> 
> Signed-off-by: Alex Shi <alex.shi@...ux.alibaba.com>
> Acked-by: Hugh Dickins <hughd@...gle.com>
> Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Cc: Vlastimil Babka <vbabka@...e.cz>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: linux-mm@...ck.org
> Cc: linux-kernel@...r.kernel.org

Acked-by: Johannes Weiner <hannes@...xchg.org>