On Fri, Mar 02, 2018 at 04:52:23PM +0000, Daniel P. Berrangé wrote:
On Thu, Mar 01, 2018 at 04:42:36PM -0700, Jim Fehlig wrote:
Locks held by virtlockd are dropped on re-exec.
virtlockd 94306 POSIX 5.4G WRITE 0 0 0 /tmp/test.qcow2 virtlockd 94306 POSIX 5B WRITE 0 0 0 /run/virtlockd.pid virtlockd 94306 POSIX 5B WRITE 0 0 0 /run/virtlockd.pid
Acquire locks in PostExecRestart code path.
This is really strange and should *not* be happening. POSIX locks are supposed to be preserved across execve() if the FD has CLOEXEC unset, and you don't fork() before the exec.
[snip]
So I wonder what we've screwed up to cause the locks to get released - reaquiring them definitely isn't desirable as we should not loose them in the first place !
This is really very strange. The problem seems to be the existance of threads at time of execve(). If you spawn a thread and the thread exits, and you execve the locks are preserved. If you spawn a thread and the thread is still running, and you execve the locks are lost. This behaviour makes no sense at all to time. Why should it matter if the thread exits itself, or is force exited during execve(). I wonder if it is even possibly a kernel bug. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|