Processes in an uninterruptable sleep

Spirilis (root@scitus.dyn.ml.org)
Sun, 9 Aug 1998 12:46:32 -0400 (EDT)

Hi,
What sort of situations can cause a process to enter an uninterruptable
sleep?
On occasion I have noticed on my system, and am noticing on a friend's 2.0.34
system, that some processes which write to tty's go into an uninterruptable
sleep and are not terminatable.
For instance, the current situation is a wall process running on tty4 where
the admin wanted to send a wall message--for some mysterious reason, the wall
process entered an uninterruptable sleep.
Doing a ps l on the process showed it was stuck in add_timer
Is this a kernel bug, or is this normal?
I've noticed similar situations with "write" processes on my own machine on
occasion. Haven't bothered to use ps l to see what syscall it's currently in
though.

Any insight will be helpful

Thanks

P.S. I'm not subscribed to the kernel list--please mail me here, or at
hannibal@bitsmart.com

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