Re: Serious reproducible 2.4.x kernel hang

[Malcolm Beattie <mbeattie@sable.ox.ac.uk>]

Malcolm Beattie writes:
> Chris Evans writes:
> > I've just managed to reproduce this personally on 2.4.0. I've had a report
> > that 2.4.1 is also affected. Both myself and the other person who
> > reproduced this have SMP i686 machines, which may or may not be relevant.
> > 
> > To reproduce, all you need to do is get my vsftpd ftp server:
> > ftp://ferret.lmh.ox.ac.uk/pub/linux/vsftpd-0.0.9.tar.gz
[...]
> As in Chris' case, vzftpd was a zombie (so Foo-ScrollLock told me) and
> all other processes were looking OK in R or S state.

Mapping the addresses from whichever ScrollLock combination produced
the task list to symbols produces the call trace
 do_exit <- do_signal <- tcp_destroy_sock <- inet_ioctl <- signal_return

The inet_ioctl is odd there--vsftpd doesn't explicitly call ioctl
anywhere at all and the next function before it in memory is
inet_shutdown which looks more believable. I have checked I'm looking
at the right System.map but I suppose I may have mis-transcribed the
address when writing it down. vsftpd doesn't make use of signal
handlers except to unset some existing ones and a SIGALRM handler
which I don't think would have triggered. Something like a seg fault
may have caused it (I should have seen an oops if it had happened in
kernel space) perhaps?

--Malcolm

-- 
Malcolm Beattie <mbeattie@sable.ox.ac.uk>
Unix Systems Programmer
Oxford University Computing Services
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