On 05/07/2013 11:04 AM, Dave Jones wrote:
On Tue, May 07, 2013 at 10:14:09AM -0400, Peter Hurley wrote:
> >> Just hit this again, by switching tty's during bootup.
> >> The previous time was switching from X to console iirc, so that seems to
be
> >> the key to triggering this.
> >
> > Sorry for not getting back to this sooner, merge window fun...
> >
> > Anyway, Peter, could this be something that your ldisc patches are
> > triggering?
>
> Yes, although early analysis also suggests the lockdep splat is possible
> regardless, just much less likely.
>
> I looked at this over the weekend, but I wasn't able to determine (in
> the limited time I had available) if the splat was valid; ie., if the
> cpu states could actually be concurrent and result in deadlock.
>
> I need to study the VT_DISALLOCATE ioctl in more detail which I plan
> to do this week.
I don't know if it proves/disproves anything, but shortly before the dump
gets printed, everything is kind of locked up. I can switch tty's, but
the gettys on them are dead to the world until after the dump.
ISTR a pause for a while when I hit this switching from X too.
It would help to know the steps to reproduce. For example, you mention
unresponsive gettys but the VT_DISALLOCATE ioctl doesn't work (and isn't
designed to) on open ttys.
Regards,
Peter Hurley
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