Bug #14787
closed
bhyve should block leases on drv purge
100%
Description
When purging (forcing them to release their holds) consumers of the vmm_drv interface which have attached to a given instance, bhyve should also go through the logic which blocks leases from being established through those existing vmm_hold references. Any lingering leases at that point (such as those used from the viona ring threads) will then be notified so they can drop their lease, cleaning out references to the to-be-destroyed vmm instance.
This was found while testing bits drafted for #14755. It was possible for bhyve consumer processes to get hung up on the way down, since the ring worker threads were not notified of the pending destruction.
Updated by Patrick Mooney 30 days ago
I dtraced the relevant calls to vmm_block_lease while destroying a vmm instance which was attached to a propolis process (although was not actively running vCPUs at the time):
16 67004 vmm_lease_block:entry vmm_lease_block
vmm`vmm_drv_purge+0x8a
vmm`vmm_do_vm_destroy_locked+0x64
vmm`vmmdev_do_vm_destroy+0xae
vmm`vmm_ctl_ioctl+0xe2
vmm`vmm_ioctl+0x10b
genunix`cdev_ioctl+0x2b
specfs`spec_ioctl+0x45
genunix`fop_ioctl+0x5b
genunix`ioctl+0x153
unix`sys_syscall+0x283
16 67008 vmm_lease_unblock:entry vmm_lease_unblock
vmm`vmm_drv_purge+0x92
vmm`vmm_do_vm_destroy_locked+0x64
vmm`vmmdev_do_vm_destroy+0xae
vmm`vmm_ctl_ioctl+0xe2
vmm`vmm_ioctl+0x10b
genunix`cdev_ioctl+0x2b
specfs`spec_ioctl+0x45
genunix`fop_ioctl+0x5b
genunix`ioctl+0x153
unix`sys_syscall+0x283
This shows the expected purge of vmm_drv leases while the instance is marked for destruction. The machine in question was dumped after this to check for kmem leaks (not that any were expected). ::findleaks was clean after the test and dump
Updated by Patrick Mooney 28 days ago
It should be noted that this ticket was filed to provide additional background for changes made as part of #14755. This was not a case of broken behavior observed in the wild, but rather a desire to make the vmm_drv portion of instance destruction more lively when it came to leases held by viona worker threads.
Updated by Electric Monk 28 days ago
- Status changed from In Progress to Closed
- % Done changed from 0 to 100
git commit a26f9c149bc8e4c9206303674cdef16edec1ca70
commit a26f9c149bc8e4c9206303674cdef16edec1ca70
Author: Patrick Mooney <pmooney@pfmooney.com>
Date: 2022-07-14T00:47:06.000Z
14755 viona should expose more ring state
14756 expose viona kernel interface version
14787 bhyve should block leases on drv purge
Reviewed by: Garrett D'Amore <garrett@damore.org>
Reviewed by: Luqman Aden <luqman@oxide.computer>
Approved by: Richard Lowe <richlowe@richlowe.net>