linux-kernel - Re: [External] Re: [PATCH] mm: hugetlb: fix a race between memory-failure/soft_offline and gather_surplus

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Message-ID: <CAMZfGtWCi7RoYE0q_7RzshvL_meSUpjWKavBOh6ifUUV6QEm+g@mail.gmail.com>
Date:   Wed, 21 Apr 2021 16:58:02 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Oscar Salvador <osalvador@...e.de>
Cc:     Michal Hocko <mhocko@...e.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Subject: Re: [External] Re: [PATCH] mm: hugetlb: fix a race between
 memory-failure/soft_offline and gather_surplus_pages

On Wed, Apr 21, 2021 at 4:49 PM Oscar Salvador <osalvador@...e.de> wrote:
>
> On Wed, Apr 21, 2021 at 04:41:10PM +0800, Muchun Song wrote:
>
> > But softoffline does not set page hwpoison before
> > __get_hwpoison_page(). So the page still can be
> > allocated. Right?
>
> Yep, soft_offline() only marks the page as hwpoison once the page has been
> fully contended and no other use is possible.
> But yeah, hugetlb is a bit trickier in that regard.
>
> This needs fixing in there.

It is OK to fix it in softoffline/memory-failure.
I just want to expose the race. Thanks.

>
>
> --
> Oscar Salvador
> SUSE L3