deadlock caused by idprio?

[Kris Kennaway]

On Sat, Nov 19, 2005 at 01:32:36PM -0500, Doug Lee wrote:
> I just ran a MySQL lookup process (written in Perl) as root prefixed
> with "idprio 1."  I expected it to take a while, but not several
> minutes.  After a while I decided to abort it, so I typed ^c in its
> `screen' window.  From then on (either from the ^c point or the idprio
> run, I know not which), I could not create any new processes, nor
> could I kill the running task.  Any attempt to do either would hang
> indefinitely.  I could end processes and work within existing
> processes as long as they didn't try to create new ones.  I entered
> the debugger (I use the alt method of <cr>~^b) and typed, among other
> things, "show lockedvnodes" and got one vnode which said "... with 22
> pending," and this count went up by 1 each time I tried creating a new
> process.  Sadly, I forgot to snapshot that screen, so I can't quote
> the rest of that entry.  I remember it said VDIR and type
> something+VOBJECT, but I don't remember what the something was.
> Unable to retrieve my system, I finally typed "panic" in the debugger
> so at least the disks would sync.  Other than "giving up on 4
> buffers," that went fine.
> 
> Any ideas what this is, and whether it's a bug?  I thought idprio was
> harmless as far as affecting other processes.

No, it's known to cause deadlocks.  I don't know if this is still the
case on 6.0.

Kris
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