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Created attachment 616104[details]
libvirt + vm logs, gdb trace
Description of problem:
A deadlock occurred in libvirt after the connection to the (single) NFS storage domain was blocked. A VM was running at the time with a disk on the storage domain.
logs attached:
* gdb trace
* libvirt log
* vm log
Version-Release number of selected component (if applicable):
libvirt-0.9.10-21.el6_3.4.x86_64
How reproducible:
?
From the gdb log, I see:
Thread 1 (Thread 0x7f9563ae6860 (LWP 2190)):
#0 0x00000032c780e054 in __lll_lock_wait () from /lib64/libpthread.so.0
No symbol table info available.
#1 0x00000032c7809388 in _L_lock_854 () from /lib64/libpthread.so.0
No symbol table info available.
#2 0x00000032c7809257 in pthread_mutex_lock () from /lib64/libpthread.so.0
No symbol table info available.
#3 0x000000000048b0ec in qemuProcessHandleAgentDestroy (agent=0x7f95500bdcd0, vm=0x7f955000c9c0) at qemu/qemu_process.c:169
priv = <value optimized out>
#4 0x0000000000465943 in qemuAgentFree (mon=0x7f95500bdcd0) at qemu/qemu_agent.c:148
No locals.
#5 qemuAgentUnref (mon=0x7f95500bdcd0) at qemu/qemu_agent.c:167
No locals.
And from upstream, I see Dan's patches to fix a deadlock in this area of code:
https://www.redhat.com/archives/libvir-list/2012-September/msg01806.htmlhttps://www.redhat.com/archives/libvir-list/2012-September/msg01812.html
I'm not sure if Dan's fix will cover this issue, but it is certainly a possibility.
Dan already backported his deadlock fixes for lxc under bug 864336, but included the qemu deadlock bugs in the process. I'm working on a scratch build.
As no one can reproduce this now, i will do code inspection and run some sanity test.
build:
libvirt-0.10.2-12.el6.x86_64
check source code:
Fix misc deadlocks in LXC and QEMU all 6 patchs already in build.
Patch59: libvirt-Fix-potential-deadlock-when-agent-is-closed.patch
Patch60: libvirt-Fix-rare-deadlock-in-QEMU-monitor-callbacks.patch
Patch61: libvirt-Convert-virLXCMonitor-to-use-virObject.patch
Patch62: libvirt-Remove-pointless-virLXCProcessMonitorDestroy-method.patch
Patch63: libvirt-Simplify-some-redundant-locking-while-unref-ing-objects.patch
Patch64: libvirt-Fix-deadlock-in-handling-EOF-in-LXC-monitor.patch
and from https://www.redhat.com/archives/libvir-list/2012-September/msg01962.html
deadlocks not occur.
do sanity test:
by Eric comments:
creating and shutting off guests while also having another thread (such as virt-manager) querying domain status , I did 300 cycles of that and no deadlocks occur.
move to verified.
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/RHSA-2013-0276.html
Created attachment 616104 [details] libvirt + vm logs, gdb trace Description of problem: A deadlock occurred in libvirt after the connection to the (single) NFS storage domain was blocked. A VM was running at the time with a disk on the storage domain. logs attached: * gdb trace * libvirt log * vm log Version-Release number of selected component (if applicable): libvirt-0.9.10-21.el6_3.4.x86_64 How reproducible: ?