[libvirt] [PATCH v4 00/23] Introduce metadata locking

[Bjoern Walk]

Michal Privoznik <mprivozn at redhat.com> [2018-09-19, 11:45AM +0200]:
> On 09/19/2018 11:17 AM, Bjoern Walk wrote:
> > Bjoern Walk <bwalk at linux.ibm.com> [2018-09-12, 01:17PM +0200]:
> >> Michal Privoznik <mprivozn at redhat.com> [2018-09-12, 11:32AM +0200]:
> 
> >>
> > 
> > Still seeing the same timeout. Is this expected behaviour?
> > 
> 
> Nope. I wonder if something has locked the path and forgot to unlock it
> (however, virtlockd should have unlocked all the paths owned by PID on
> connection close), or something is still holding the lock and connection
> opened.
> 
> Can you see the timeout even when you turn off the selinux driver
> (security_driver="none' in qemu.conf)? I tried to reproduce the issue
> yesterday and was unsuccessful. Do you have any steps to reproduce?

So, I haven't been able to actually dig into the debugging but we have
been able to reproduce this behaviour on x86 (both with SELinux and
DAC). Looks like a general problem, if a problem at all, because from
what I can see in the code, the 60 seconds timeout is actually intended,
or not? The security manager does try for 60 seconds to acquire the lock
and only then bails out. Why is this?

However, an actual bug is that while the security manager waits for the
lock acquire the whole libvirtd hangs, but from what I understood and
Marc explained to me, this is more of a pathological error in libvirt
behaviour with various domain locks.

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