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From:   Mikael Pettersson <mikpelinux@gmail.com>
Date:   Sun, 8 Aug 2021 12:44:45 +0200
Message-ID: <CAM43=SNV4016i2ByssN9tvXDN6ZyQiYM218_NkrebyPA=p6Rcg@mail.gmail.com>
Subject: Re: [BISECTED][REGRESSION] 5.10.56 longterm kernel breakage on m68k/aranym
To:     Finn Thain <fthain@linux-m68k.org>
Cc:     Linux Kernel list <linux-kernel@vger.kernel.org>,
        linux-m68k@lists.linux-m68k.org, stable@vger.kernel.org
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On Sun, Aug 8, 2021 at 1:20 AM Finn Thain <fthain@linux-m68k.org> wrote:
>
> On Sat, 7 Aug 2021, Mikael Pettersson wrote:
>
> > I updated the 5.10 longterm kernel on one of my m68k/aranym VMs from
> > 5.10.47 to 5.10.56, and the new kernel failed to boot:
> >
> > ARAnyM 1.1.0
> > Using config file: 'aranym1.headless.config'
> > Could not open joystick 0
> > ARAnyM RTC Timer: /dev/rtc: Permission denied
> > ARAnyM LILO: Error loading ramdisk 'root.bin'
> > Blitter tried to read byte from register ff8a00 at 0077ee
> >
> > At this point it kept running, but produced no output to the console,
> > and would never get to the point of starting user-space. Attaching gdb
> > to aranym showed nothing interesting, i.e. it seemed to be executing
> > normally.
> >
> > A git bisect identified the following commit between 5.10.52 and
> > 5.10.53 as the culprit:
> > # first bad commit: [9e1cf2d1ed37c934c9935f2c0b2f8b15d9355654]
> > mm/userfaultfd: fix uffd-wp special cases for fork()
> >
>
> That commit appeared in mainline between v5.13 and v5.14-rc1. Is mainline
> also affected? e.g. v5.14-rc4.

5.14-rc4 boots fine. I suspect the commit has some dependency that
hasn't been backported to 5.10 stable.