Bug 2217885

Summary:	Instance spawn failing with "Failed to build and run instance: libvirt.libvirtError: internal error: Process exited prior to exec: libvirt: QEMU Driver error : failed to umount devfs on /dev: Device or resource busy"
Product:	[Fedora] Fedora	Reporter:	Malte Poll <malte.poll>
Component:	libvirt	Assignee:	Libvirt Maintainers <libvirt-maint>
Status:	NEW ---	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	unspecified
Version:	38	CC:	berrange, clalancette, crobinso, jforbes, laine, libvirt-maint, virt-maint
Target Milestone:	---
Target Release:	---
Hardware:	x86_64
OS:	Linux
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Last Closed:		Type:	Bug
Regression:	---	Mount Type:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Malte Poll 2023-06-27 11:27:39 UTC

Description of problem:

Libvirt does not deal with nested mounts correctly when unmounting /dev.
This prevents libvirt from working in cases where /dev contains nested mounts (this is the case in containers),

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

v9.0.0 (fixed in v9.1.0 upstream)


How reproducible:


Steps to Reproduce:
1. mount -t tmpfs tmpfs /dev/shm && mount -t tmpfs tmpfs /dev/shm
2. try to create any VM with libvirt

Actual results:

libvirt fails with error:

Instance spawn failing with "Failed to build and run instance: libvirt.libvirtError: internal error: Process exited prior to exec: libvirt: QEMU Driver error : failed to umount devfs on /dev: Device or resource busy"


Expected results:

VM should be created.


Additional info:

- Tracking link for RHEL: https://bugzilla.redhat.com/show_bug.cgi?id=2167302
- Upstream fix was published here: https://listman.redhat.com/archives/libvir-list/2023-February/237603.html
- Upstream fix was released in libvirt >= 9.1