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Description of problem:
See this upstream thread: https://www.redhat.com/archives/libvir-list/2011-July/msg01969.html
Running a loop of 'virsh managedsave dom && virsh start dom' while virt-manager is connected to libvirtd is able to crash libvirtd because both a sync job (the query commands used by virt-manager) and async job (the managed save) can end up trying to use the qemu monitor at the same time.
Version-Release number of selected component (if applicable):
libvirt-0.9.4-0rc2.el6.x86_64
How reproducible:
I was able to get a loop to crash within 10 iterations pre-patch; post patch got 20 iterations without failure.
Steps to Reproduce:
1. for i in `seq 20`; do virsh managedsave dom && virsh start dom || { echo failed on $i; break; }; done
2.
3.
Actual results:
error: Failed to save domain dom state
error: End of file while reading data: Input/output error
and libvirtd is crashed
Expected results:
no crash
Additional info:
proposed upstream patch:
https://www.redhat.com/archives/libvir-list/2011-July/msg02077.html
That thread mentioned another potential issue with killing libvirtd in the middle of a managed save, but I think it is a distinct issue and will be opening a second bz.
In POST:
commit 193cd0f3c879619619a3c35d25311e98693fe2ef
Author: Eric Blake <eblake>
Date: Thu Jul 28 17:18:24 2011 -0600
qemu: fix crash when mixing sync and async monitor jobs
Currently, we attempt to run sync job and async job at the same time. It
means that the monitor commands for two jobs can be run in any order.
In the function qemuDomainObjEnterMonitorInternal():
if (priv->job.active == QEMU_JOB_NONE && priv->job.asyncJob) {
if (qemuDomainObjBeginNestedJob(driver, obj) < 0)
We check whether the caller is an async job by priv->job.active and
priv->job.asynJob. But when an async job is running, and a sync job is
also running at the time of the check, then priv->job.active is not
QEMU_JOB_NONE. So we cannot check whether the caller is an async job
in the function qemuDomainObjEnterMonitorInternal(), and must instead
put the burden on the caller to tell us when an async command wants
to do a nested job.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
http://rhn.redhat.com/errata/RHBA-2011-1513.html