** Description changed:
+ [Impact]
+
A mutual customer is reporting ssh is not working on a Xenial based VM.
This VM is running the 4.4 based Xenial kernel and not a custom linux-
azure kernel.
After an investigation this is a known old signaling issue. The 4.4
based Xenial kernels require the following patch:
vmbus: fix missing signaling in hv_signal_on_read()
(https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=13c5e97701091f9b02ded0c68809f8a6b08c747a).
The patch is not in the upstream stable 4.4 tree, because it’s not
needed there.
Compared to the upstream 4.4 tree, Ubuntu 4.4.0-124-generic integrated
more hv patches from the mainline kernel, e.g. Drivers: hv: vmbus:
finally fix hv_need_to_signal_on_read(), so it must pick up the above
patch.
We checked the latest Ubuntu 4.4 kernel
(https://kernel.ubuntu.com/git/ubuntu/ubuntu-
xenial.git/tree/?h=Ubuntu-4.4.0-146.172) and the patch is also absent
there.
The patch (13c5e97701091f9b02ded0c68809f8a6b08c747a) can be cleanly
cherry-picked into Ubuntu-4.4.0-146.172.
+
+ [Test Case]
+
+ When the issue happens, there is no error message in dmesg or syslog,
+ and it's just the host side NetVSP driver stops reading from the guest-
+ to-host ring, and the guest network stops working. So we don't really
+ have any logs to provide here.
+
+ [Regression Potential]
+
+ Low risk since that's a simple patch from stable upstream touching only
+ Hyper-V specific code.
** Also affects: linux (Ubuntu Xenial)
Importance: Undecided
Status: New
** Changed in: linux (Ubuntu Xenial)
Status: New => In Progress
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https://bugs.launchpad.net/bugs/1826416
Title:
[Xenial] Customer can not SSH to Linux VM due to "VSC State Unhealthy"
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