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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Mon, 2 May 2022 11:10:25 +0200
Message-ID: <CAMuHMdW-afrvM9KpEBSGaaLQzQSzjez7bCgtxXEp49OdcAXKhw@mail.gmail.com>
Subject: Re: [PATCH] mapletree-vs-khugepaged
To:     Liam Howlett <liam.howlett@oracle.com>
Cc:     Heiko Carstens <hca@linux.ibm.com>,
        Guenter Roeck <linux@roeck-us.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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Hi Liam,

On Sat, Apr 30, 2022 at 1:58 AM Liam Howlett <liam.howlett@oracle.com> wrote:
> * Heiko Carstens <hca@linux.ibm.com> [220429 09:19]:
> > On Fri, Apr 29, 2022 at 01:01:53PM +0000, Liam Howlett wrote:
> > > * Heiko Carstens <hca@linux.ibm.com> [220429 08:10]:
> > > > On Thu, Apr 28, 2022 at 10:20:40AM -0700, Guenter Roeck wrote:
> > > > > On Wed, Apr 27, 2022 at 03:10:45PM -0700, Andrew Morton wrote:
> > > > > > Fix mapletree for patch series "Make khugepaged collapse readonly FS THP
> > > > > > more consistent", v3.
> > > > > >
> > > > > > Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
> > > > > > Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> > > > >
> > > > > This patch causes all my sparc64 boot tests to fail. Bisect and crash logs
> > > > > attached.
> > > > >
> > > > > Guenter
> > ...
> > > >
> > > > FWIW, same on s390 - linux-next is completely broken. Note: I didn't
> > > > bisect, but given that the call trace, and even the failing address
> > > > match, I'm quite confident it is the same reason.
> > >
> > > This is worth a lot to me.  Thanks for the report and the testing.
> >
> > Not sure if it is of any relevance, and you are probably aware if it
> > anyway, but both sparc64 and s390 are big endian; and there was no
> > report from little endian architectures yet.
>
> I was aware they are big endian, but thanks - the more info the better.
> sparc64 is technically bi-endian but I think everyone runs it in big

Sparc64 is big-endian. It has support for accessing little endian data
in memory, but that's merely an optimization.

> endian mode?  Is alpha the same?  There was a report of alpha having

Alpha is little-endian.

> issues too. m68k is also big endian - but also nommu, so that makes
> testing difficult.

M68k exists with and without MMU.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds