4BSD Scheduler Problem on 5.3
jhb at FreeBSD.org
Fri Apr 1 10:38:42 PST 2005
On Thursday 31 March 2005 08:03 pm, Robert Watson wrote:
> On Thu, 31 Mar 2005, John Baldwin wrote:
> > On Thursday 31 March 2005 03:38 pm, William Michael Grim wrote:
> > > Hello.
> > >
> > > I keep having kernel panics every couple weeks on my system. It occurs
> > > in the sched_switch() function. There are several other statements in
> > > the backtrace involving "??"; what are those?
> > >
> > > I have attached the dump output and system info to this email. Any
> > > feedback would be helpful.
> > >
> > > Thanks so much for your help.
> > The real trace ends with Xint0x80_syscall(). The rest after that is
> > garbage memory. Your real problem is in exit1() or ttywakeup(). Since
> > ttywakeup() doesn't call exit1() (AFAIK), the exit1() frame is probably
> > bogus (gdb doesn't grok trapframes maybe?) and the real bug is a NULL
> > pointer deref in ttywakeup(). Perhaps it's a bug in the ptc driver?
> > (ptcopen is in the trace). What is the ptc driver anyway?
> I think we have a race in -STABLE relating to tty wakeups and
> open/close/device teardown. I've seen a panic relating to sio during a
> tty close on RELENG_5 about 5-6 months ago, but was unable to get a dump.
> Scott has since fixed dumps with twe, but I've not yet been able to get
> the bug to recur. I'll give it another try.
Sounds very plausible. Does Poul-Henning have any ideas?
John Baldwin <jhb at FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve" = http://www.FreeBSD.org
More information about the freebsd-hackers