Received-SPF: pass (google.com: domain of linux-kernel+bounces-179208-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Precedence: bulk
MIME-Version: 1.0
References: <20240511035435.1477004-1-linmiaohe@huawei.com>
 <20240514141439.55fba39c81c1af55c9a100e1@linux-foundation.org>
 <CAHbLzkq+NBjwjSvU1fQe56nLf5mmGp65TH8hDpb66EFLENctKA@mail.gmail.com> <20240514144204.88790f125b0275ef68acf6de@linux-foundation.org>
In-Reply-To: <20240514144204.88790f125b0275ef68acf6de@linux-foundation.org>
From: Yang Shi <shy828301@gmail.com>
Date: Tue, 14 May 2024 15:55:52 -0600
Message-ID: <CAHbLzkpQvr2K5yxwmtoHsj_UJ78ak=m-YdZxk=vpnPJ8iZdncw@mail.gmail.com>
Subject: Re: [PATCH -rc7] mm/huge_memory: mark huge_zero_page reserved
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>, nao.horiguchi@gmail.com, xuyu@linux.alibaba.com, 
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Tue, May 14, 2024 at 3:42=E2=80=AFPM Andrew Morton <akpm@linux-foundatio=
n.org> wrote:
>
> On Tue, 14 May 2024 15:28:12 -0600 Yang Shi <shy828301@gmail.com> wrote:
>
> > On Tue, May 14, 2024 at 3:14=E2=80=AFPM Andrew Morton <akpm@linux-found=
ation.org> wrote:
> > >
> > > On Sat, 11 May 2024 11:54:35 +0800 Miaohe Lin <linmiaohe@huawei.com> =
wrote:
> > >
> > > > When I did memory failure tests recently, below panic occurs:
> > > >
> > > >  kernel BUG at include/linux/mm.h:1135!
> > > >  invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
> > > >  CPU: 9 PID: 137 Comm: kswapd1 Not tainted 6.9.0-rc4-00491-gd5ce28f=
156fe-dirty #14
> > > >
> > > > ...
> > > >
> > > > --- a/mm/huge_memory.c
> > > > +++ b/mm/huge_memory.c
> > > > @@ -208,6 +208,7 @@ static bool get_huge_zero_page(void)
> > > >               __free_pages(zero_page, compound_order(zero_page));
> > > >               goto retry;
> > > >       }
> > > > +     __SetPageReserved(zero_page);
> > > >       WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page));
> > > >
> > > >       /* We take additional reference here. It will be put back by =
shrinker */
> > > > @@ -260,6 +261,7 @@ static unsigned long shrink_huge_zero_page_scan=
(struct shrinker *shrink,
> > > >               struct page *zero_page =3D xchg(&huge_zero_page, NULL=
);
> > > >               BUG_ON(zero_page =3D=3D NULL);
> > > >               WRITE_ONCE(huge_zero_pfn, ~0UL);
> > > > +             __ClearPageReserved(zero_page);
> > > >               __free_pages(zero_page, compound_order(zero_page));
> > > >               return HPAGE_PMD_NR;
> > > >       }
> > >
> > > This causes a bit of a mess when staged ahead of mm-stable.  So to
> > > avoid disruption I staged it behind mm-stable.  This means that when
> > > the -stable maintainers try to merge it, they will ask for a fixed up
> > > version for older kernels so you can please just send them this
> > > version.
> >
> > Can you please drop this from mm-unstable since both I and David
> > nack'ed a similar patch in another thread.
> > https://lore.kernel.org/linux-mm/20240511032801.1295023-1-linmiaohe@hua=
wei.com/
>
> That appears to link to the incorrect email thread?

I meant that patch is actually same with this one. Just used folio
interface instead of page. I'm not sure why Miaohe posted two. Maybe
target to different version.