Re: [BUG] wait_for_devfsd_finished deadlock

[Richard Gooch <rgooch@ras.ucalgary.ca>]

William Lee Irwin, III writes:
> While testing 2.4.17-pre1 with some other patches, a situation
> reminiscent of a deadlock arose. mutt(1) would block indefinitely
> while opening a large mbox, and all further calls to sys_open()
> would block indefinitely.
> 
> After some further testing to isolate the problem, I reproduced this
> behavior in the vanilla 2.4.17-pre1 kernel. The sysrq output showed
> a number of processes with the following call trace in the devfs
> core:

Your sh process appears to be hung in wait_for_devfsd_finished(). It
would be helpful to know what devfsd was doing at this time. If it
were hung internally (in user-space), it would account for this
behaviour. However, if devfsd crashes, then devfsd_close() will be
called, which will wake any waiters.

> And the following call traces elsewhere:

Are these related?
cron		->	pipe_wait()
procmail	->	interruptible_sleep_on_locked()
exim		->	sys_wait4()

Maybe these are just waiting on mutt(1)?

> Further diagnostic information is available upon request.

That's what I like to hear. Set CONFIG_DEVFS_DEBUG=y and boot with
"devfs=dall" and send me the (verbose) kernel logs. That should show
the sequence of events that lead to this.

> Mr. Gooch, your attention to this matter is much appreciated.

Just "Richard" is fine. I'm not a fan of formality.

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca