[Bug 2083845] Re: Setting I/O scheduler to 'none' causes error in oracular

This bug was fixed in the package linux - 6.11.0-9.9

---------------
linux (6.11.0-9.9) oracular; urgency=medium

* oracular/linux: 6.11.0-9.9 -proposed tracker (LP: #2084250)

* re-enable Ubuntu FAN in the Noble kernel (LP: #2064508)
- SAUCE: fan: add VXLAN implementation
- SAUCE: fan: Fix NULL pointer dereference
- SAUCE: fan: support vxlan strict length validation

* update for V3 kernel bits and improved multiple fan slice support
(LP: #1470091) // re-enable Ubuntu FAN in the Noble kernel (LP: #2064508)
- SAUCE: fan: tunnel multiple mapping mode (v3)

* Setting I/O scheduler to 'none' causes error in oracular (LP: #2083845)
- block: Fix elv_iosched_local_module handling of "none" scheduler

* Miscellaneous Ubuntu changes
- [Config] Update toolchain versions

-- Timo Aaltonen <timo.aaltonen@canonical.com> Mon, 14 Oct 2024
14:20:00 +0300

** Changed in: linux (Ubuntu)
Status: New => Fix Released

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https://bugs.launchpad.net/bugs/2083845

Title:
Setting I/O scheduler to 'none' causes error in oracular

Status in linux package in Ubuntu:
Fix Released
Status in linux-gcp package in Ubuntu:
Fix Released

Bug description:
[Impact]
With Oracular linux-gcp kernel version 6.11.0-1002.2, running the google-guest-agent causes an error. The guest-agent sets the I/O scheduler to 'none', causing errors such as below:

```
2024-10-07T09:24:03.262548+00:00 oracular-old-gga-test google_guest_agent[1125]: panic: invalid return from write: got 256 from a write of 4
```

With strace, we can also see that the return value of write is
unexpected:

[pid 3127] write(7, "none", 4) = 256

This is breaking provision of GCP cloud images, so bump it to
Critical.

[Fix]

Fix commit is e3accac1a976e65491a9b9fba82ce8ddbd3d2389 ("block: Fix
elv_iosched_local_module handling of "none" scheduler").

[How to test]

Apply the fix, rebuild the kernel and try to change scheduler in
sysfs, e.g.:

# echo "none" > /sys/devices/virtual/block/loop1/queue/scheduler
# echo $?
0

[Regression potential]

Upstream clean cherry-pick, already part of v6.11.2.

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