Bug 2037765

Summary: Memory hot unplug not working correctly after suspend+resume
Product: Red Hat Enterprise Linux 8 Reporter: Milan Zamazal <mzamazal>
Component: libvirtAssignee: Virtualization Maintenance <virt-maint>
Status: CLOSED DUPLICATE QA Contact: Virtualization Bugs <virt-bugs>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 8.6CC: pkrempa, virt-maint
Target Milestone: rcFlags: pm-rhel: mirror+
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Last Closed: 2022-01-06 14:13:31 UTC Type: Bug
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Description Milan Zamazal 2022-01-06 14:08:04 UTC 
Description of problem:

When a VM with a hot plugged memory is suspended, then resumed and then the previously hot plugged memory is unplugged, the DIMM remains in the domain XML despite the memory is successfully removed from the guest OS.

Version-Release number of selected component (if applicable):

libvirt-daemon-7.10.0-1.module+el8.6.0+13502+4f24a11d.x86_64
qemu-kvm-6.2.0-1.module+el8.6.0+13725+61ae1949.x86_64
kernel-4.18.0-357.el8.x86_64

How reproducible:

100%

Steps to Reproduce:
1. Start a VM.
2. Hot plug 256 MB memory to it.
3. Suspend the VM.
4. Resume the VM.
5. Hot unplug the previously unplugged memory.

Actual results:

The memory is unplugged from the guest OS but the domain XML keeps reporting the old amount of memory and the given DIMM is still present, even after a long time.

Expected results:

The memory is unplugged from the guest OS and is removed from the domain XML.

Additional info:

This is apparently a regression, started being observed after a recent update to QEMU 6.2. It happens in RHV/oVirt environments.
Comment 1 Peter Krempa 2022-01-06 14:13:31 UTC 

*** This bug has been marked as a duplicate of bug 2035237 ***
Comment 2 Peter Krempa 2022-01-06 14:15:01 UTC 
All hot-unplug of devices which were cold-plugged is broken.