Re: ufs related panic with latest current

Tomi Vainio - Sun Finland <Tomi.Vainio_at_Sun.COM> writes:
> Dag-Erling Smørgrav writes:
>  > Tomi Vainio - Sun Finland <Tomi.Vainio_at_Sun.COM> writes:
>  > > First maxusers was 0 then when changed it to 8.
>  > That's a regression.  Keep it at 0.
> I understood that there is a bug on new kmem allocator and this was an
> attempt to reduce kmem allocations but it didn't help.  Do you know if
> this is going to fixed somehow or should people just install more
> memory to get system stay up?

Well, reducing maxusers isn't going to help much as it only controls a
small part of kernel memory, and setting it too low may render the
system unusable.

The backtrace you showed seems to indicate that the panic happened
somewhere in the softupdates code, but IIRC that code has a fairly
conservative built-in limit on memory consumption and degrades
gracefully when it hits that limit.  It's likely that something else
gobbled up all available kernel memory, and the mallloc() call from
softupdates was simply the straw that broke the camel's back.

If you have a serial console hooked up, you could try running

    while :; do vmstat -m ; sleep 1 ; done

on the serial console while doing whatever it is you do that causes
the problem.  This will tell you how much kernel memory was in use at
the time of the panic and what it was used for.

DES
-- 
Dag-Erling Smørgrav - des_at_des.no