linux-kernel - Re: [External] Re: [PATCH v10 04/11] mm/hugetlb: Defer freeing of HugeTLB pages

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Message-ID: <CAMZfGtXgzorGv_hymZF_cJPv2qziVG6xN5hCGFqT3KOjCZOteg@mail.gmail.com>
Date:   Mon, 21 Dec 2020 23:18:11 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Oscar Salvador <osalvador@...e.de>
Cc:     Jonathan Corbet <corbet@....net>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>, mingo@...hat.com,
        bp@...en8.de, x86@...nel.org, hpa@...or.com,
        dave.hansen@...ux.intel.com, luto@...nel.org,
        Peter Zijlstra <peterz@...radead.org>, viro@...iv.linux.org.uk,
        Andrew Morton <akpm@...ux-foundation.org>, paulmck@...nel.org,
        mchehab+huawei@...nel.org, pawan.kumar.gupta@...ux.intel.com,
        Randy Dunlap <rdunlap@...radead.org>, oneukum@...e.com,
        anshuman.khandual@....com, jroedel@...e.de,
        Mina Almasry <almasrymina@...gle.com>,
        David Rientjes <rientjes@...gle.com>,
        Matthew Wilcox <willy@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        "Song Bao Hua (Barry Song)" <song.bao.hua@...ilicon.com>,
        David Hildenbrand <david@...hat.com>, naoya.horiguchi@....com,
        Xiongchun duan <duanxiongchun@...edance.com>,
        linux-doc@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [External] Re: [PATCH v10 04/11] mm/hugetlb: Defer freeing of
 HugeTLB pages

On Mon, Dec 21, 2020 at 10:14 PM Oscar Salvador <osalvador@...e.de> wrote:
>
> On Mon, Dec 21, 2020 at 07:07:18PM +0800, Muchun Song wrote:
> > > The above implies that update_and_free_page() is __always__ called from a
> > > non-task context, but that is not always the case?
> >
> > IIUC, here is always the case.
>
> I might be missing something obvious, so bear with me.
>
> I guess you are refering to the call __free_huge_page()->update_and_free_page().
> AFAICS, free_huge_page might call __free_huge_page right away when in task
> context, and so, we would be calling update_and_free in a task context as well.

Yeah. You are right. I mean the call __free_huge_page()->update_and_free_page().
Because update_and_free_page is called under hugetlb_lock, it is
non-task context,
right?


>
> Or are you referring to the other callers?
>
> --
> Oscar Salvador
> SUSE L3



-- 
Yours,
Muchun