random MIPS TLB exceptions?

[Juli Mallett]

On Mon, Sep 16, 2013 at 1:09 AM, Adrian Chadd <adrian at freebsd.org> wrote:

> Hiya,
>
> I just saw a random panic on MIPS in kernel code where it shouldn't occur.
> It hasn't happened after a reboot.
>
> Has anyone else seen occasional TLB exceptions?
>

Not enough information.  There is no "MIPS" kernel and no "MIPS" platform,
so it's hard to make sense of the problem space here.  My instinct would be
that sporadic issues of this kind could often be caused by a driver or
similar, so it would be helpful to know what hardware you're using, what
kernel you're running, and what kind of workload is going on.  It could be
something that others simply haven't hit for circumstantial reasons (say, a
problem related to swapping), or based on what drivers and hardware are
in-use.  (Is there wireless involved?  Doesn't that bring in all kinds of
timers and occasional beacons that could be received?  That kind of thing
seems like it could result in sporadic crashes.)

Did you get any kind of backtrace?  Was it actually a "TLB exception"
(which has a specific meaning), or do you really just mean you're seeing
random panics and that you think the TLB might be implicated?  What kind of
TLB exception?  Load, store, modify?

I haven't seen anything like what you describe, I don't think, but I'm also
not sure what you're describing.  Hopefully we can track this down.

Thanks,
Juli.