Bug#918764: udev: "udevadm control --reload-rules" kills all processes except init

[Axel Beckert]

Hi,

two more situations where this happens for me:

Axel Beckert wrote:
> I have no idea why this is happening, but several packages use "udevadm
> control --reload-rules" in their postinst (e.g. fuse) and if that's run,
> all process except init are instantly killed […]

It just happened again, triggered by wireshark-dkms (aptitude upgrade
ran via ssh):

------------------------------snip------------------------------
Version: 0.0.20190123
Kernel:  4.18.0-3-amd64 (x86_64)
-------------------------------------

Status: Before uninstall, this module version was ACTIVE on this kernel.

wireguard.ko:
 - Uninstallation
   - Deleting from: /lib/modules/4.18.0-3-amd64/updates/dkms/
rmdir: failed to remove 'updates/dkms': Directory not empty
 - Original module
   - No original module was found for this module on this kernel.
   - Use the dkms install command to reinstall any previous module version.

depmod...

DKMS: uninstall completed.

------------------------------
Deleting module version: 0.0.20190123
completely from the DKMS tree.
------------------------------
Done.
Loading new wireguard-0.0.20190123 DKMS files...
Building for 4.18.0-3-amd64 4.20.0-trunk-amd64
Building initial module for 4.18.0-3-amd64
Done.

wireguard.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/4.18.0-3-amd64/updates/dkms/

depmod...

DKMS: install completed.
Building initial module for 4.20.0-trunk-amd64
packet_write_wait: Connection to UNKNOWN port 65535: Broken pipe
------------------------------snap------------------------------

So for some reason it was only triggered when building the module for
4.20.0-trunk-amd64, but not for 4.18.0-3-amd64 (which was running at that time).


Another case which predates my original bug report by a few weeks
(week before christmas or maybe even mid-december), but which I now
noticed that it had the exact same symptoms:

I have three screens connected to my workstation:

1x DisplayPort
1x HDMI
1x DVI-D

All three screens are powered via the same switchable power strip.
Everything was fine when I powered all three screens of by turning of
the powerstrip.

But when I powered them on again by turning on the power strip again,
the machine showed the same symptoms. I remember that because I was
confused that the machine just "crashed" that moment I wanted to use
it again after a long weekend where I was only logged in remotely, if
at all.

Will verify this suspected relation as soon as I'm back home again as
it now doesn't matter anymore as there is no X session anymore I'd
have to rebuild upon relogin as I'll have to do that anyway. I also
intend to power on the three screens one by one to see which type of
screen triggers it. (My guess would be DisplayPort.)


I also plan to check if my "does not happen in the first 20 minutes
after reboot" is actually the "does not happen until udev is restarted
at least once after reboot" mentioned by some other victim of this
bug.

And if that's the case and powering on a monitor triggers it, too, it
looks to me as this indeed a bug in udev. The only other possibility I
see with these symptoms would be a bug in the kernel's device handling
since at least 4.18.x.


And I think this issue should go back to RC-severity, now that at
least 3 or 4 persons are affected, independent of being a bug in udev
or somewhere else.

		Regards, Axel
-- 
 ,''`.  |  Axel Beckert <abe at debian.org>, https://people.debian.org/~abe/
: :' :  |  Debian Developer, ftp.ch.debian.org Admin
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