linux-kernel - Re: [PATCH 04/16] mm/migration: reduce the rcu lock duration

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Message-ID: <CAMZfGtUUG3KqMLWs32vL7fwUAVhgJuiE4OvW_B0K1zeR8oacVw@mail.gmail.com>
Date:   Fri, 4 Mar 2022 20:16:46 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Miaohe Lin <linmiaohe@...wei.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Yang Shi <shy828301@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        Huang Ying <ying.huang@...el.com>, Zi Yan <ziy@...dia.com>,
        Minchan Kim <minchan@...nel.org>,
        Alistair Popple <apopple@...dia.com>,
        ave.hansen@...ux.intel.com, o451686892@...il.com,
        Mina Almasry <almasrymina@...gle.com>,
        John Hubbard <jhubbard@...dia.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        Peter Xu <peterx@...hat.com>,
        HORIGUCHI NAOYA(堀口 直也) 
        <naoya.horiguchi@....com>, Michal Hocko <mhocko@...e.com>,
        riel@...hat.com, Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 04/16] mm/migration: reduce the rcu lock duration

On Fri, Mar 4, 2022 at 5:35 PM Miaohe Lin <linmiaohe@...wei.com> wrote:
>
> rcu_read_lock is required by grabbing the task refcount but it's not
> needed for ptrace_may_access. So we could release the rcu lock after
> task refcount is successfully grabbed to reduce the rcu holding time.
>
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>

Also simple.

Reviewed-by: Muchun Song <songmuchun@...edance.com>