On Mon, Aug 9, 2021 at 3:59 AM Finn Thain [off-list ref] wrote:

On Sun, 8 Aug 2021, Mikael Pettersson wrote:

quoted

On Sun, Aug 8, 2021 at 1:20 AM Finn Thain [off-list ref] wrote:

quoted

On Sat, 7 Aug 2021, Mikael Pettersson wrote:

quoted

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.

On mainline, 9e1cf2d1ed3 is known as commit 8f34f1eac382 ("mm/userfaultfd:
fix uffd-wp special cases for fork()").

There are differences between the two commits that may be relevant. I
don't know.

If you checkout 8f34f1eac382 and if that works, it would indicate either
missing dependencies in -stable, or those differences are important.

OTOH, if 8f34f1eac382 fails in the same way as linux-5.10.y, it would
indicate that -stable is missing a fix that's present in v5.14-rc4.

8f34f1eac382 boots fine.