Public bug reported:
Hello! I'm a programmer employed by VMWare. We're using Ubuntu Xenial,
have an ESM contract, and have run into what we believe to be a nasty
interaction between a kernel change and the `cdrom_id --eject-media`
command. This problem started happening after upgrading from 4.15.0-154
to 4.15.0-156.
I am reporting a kernel "device change" event storm that appears to not
stop on its own and is triggered by both ejecting media from a DVD-ROM
drive AND having a udev rule which contains the following line:
ENV{DISK_EJECT_REQUEST}=="?*", RUN+="cdrom_id --eject-media $devnode",
GOTO="cdrom_end"
If you eliminate this line from your udev rule file, the storm will
never happen. This strongly suggests that the cdrom_id program is a key
component in the problem. As mentioned before, this problem happened
after we upgraded from kernel 4.15.0-154 to kernel 4.15.0-156 as part of
a regular update to the Canonical-included packages that we use as a
base for our system. Based on the evidence, we believe that this is a
regression from kernel version 4.15.0-154.
This storm prevents new media inserted into the drive from being
recognized and mounted. In order for any new media inserted into the
drive to be recognized, one must terminate the storm by do one of two
things:
Either:
Move `/lib/udev/cdrom_id` to some other location, wait for a moment for the
storm to stop, then move it back. Media inserted into the drive will be
immediately recognized.
or:
Insert the media several times until it stays inserted. In testing "several"
has been "three or four", but I have no idea of the upper or lower bounds of
this number. Each time you insert the media, it will be automatically removed
from the VM. On the insertion immediately _before_ the one that actually works,
the event storm will stop, and the media will be -again- automatically removed.
On the next insertion, the media will stay in, and you will be able to actually
mount the media inside the VM.
When you look at the output of `udevadm monitor -u -k` during the event
storm the following event is generated at a rate roughly ten times per
second:
KERNEL[3198.914510] change
/devices/pci0000:00/0000:00:07.1/ata1/host0/target0:0:0/0:0:0:0/block/sr0
(block)
UDEV [3199.021261] change
/devices/pci0000:00/0000:00:07.1/ata1/host0/target0:0:0/0:0:0:0/block/sr0
(block)
Relevant system information:
OS: Ubuntu Xenial ESM
IAAS: vSphere 7.0
uname -a output: Linux test-machine 4.15.0-156-generic #163~16.04.1-Ubuntu SMP
Mon Aug 23 13:38:23 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
Likely Reproduction Steps:
1) Boot a machine (virtual or otherwise) with an attached DVD-ROM drive with
the 4.15.0-156-generic kernel.
2) Insert media into the drive.
3) Eject the media.
4) Notice that `udevadm monitor -u -k` is showing you an endless stream of
"device change" events.
If you need any additional information or resources from us, please
don't hesitate to ask. I expect that if you folks need a vSphere
environment, we'll be able to provide one.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1944642
Title:
Xenial (ESM) - 4.15.0-156 creates event storm when ejecting DVD-ROM
media
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