Subject: kern/15099: 1.5.2/i386 kernel panic from userland via gkrellm plugin: "lockmgr: pid %d, not exclusive lock holder %d unlocking"
To: None <>
From: Douglas Brebner <>
List: netbsd-bugs
Date: 12/31/2001 00:37:49
>Number:         15099
>Category:       kern
>Synopsis:       Can panic 1.5.2/i386 kernel from userland
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Dec 30 16:38:00 PST 2001
>Originator:     Douglas Brebner
>Release:        NetBSD-1.5.2/i386
System: NetBSD aoife.home 1.5.2 NetBSD 1.5.2 (AOIFE.1.5) #0: Fri Nov 30 00:01:03 GMT 2001 douglas@aoife.home:/usr/src/syssrc/sys/arch/i386/compile/AOIFE.1.5 i386

	I have been able to crash the 1.5.2 kernel via the userland program gkrellm and the gkrellkam plugin. I run gkrellm-1.2.4 with the gkrellkam plugin version 0.2.5 from

	The panic is "lockmgr: pid %d, not exclusive lock holder %d unlocking"

	This bug is erratic. The panic sometimes occur immediately, sometimes later. A symptom of the latter case is that if gkrellm is restarted, it will run but the display will not appear.
	The kernel also usually crashes without a coredump but I do have one approx 400MB
	I cannot be certain that the crashes without coredumps are the same panic as described above.

	Set up the kam plugin to display images using xv.
	Click on a kam monitor in gkrellm. 
	Kill gkrellm.
	When the xv windows are closed, the kernel panics with a "lockmgr: pid %d, not exclusive lock holder %d unlocking" panic.