Re: NetBSD 7.1.1 instability - hangs

[Riccardo Mottola <riccardo.mottola%libero.it@localhost>]

Hi Robert,

I did some tests.

On 2018-03-10 00:01:27 +0000 Robert Elz <kre%munnari.OZ.AU@localhost> wrote:

>   | X does not get "killed" either, I do not return to console.
>
> If it gets killed, that (not returning to console) is expected.
>
>   | On this system usually the X driver is decently well-behaved,
> That I believe takes assistance from the X server.
>
>   | so while things work I can switch to terminals,
>
> Yes, the working server helps with the transition.
>
>   | if X was being killed by  | out-of-swap, I'd expect to get to the 
> console 
> again.
>
> I wouldn't.   But you can easily test that - just start X
> (no need for anything huge like ruse - the "by out of
> swap" is not important for this test)  and kill -9 the
> X server process.   Observe what happens.   You might
> want to make sure you can ssh in (or have already done
> that) so you can gracefully reboot.

I tried by telneting into the box and
1) killed with normal signal: recovery is perfect
2) killed with -9 as you suggested: recovery is almost perfect: I get 
back to console (framebuffer, actually) although only with a cursoer. 
I am on a wrong terminal, switching console gives me back to the 
original prompt.

I'd say that is quite fine.

> Of course, this does not mean that this is what is happening
> in the situation in question, it could also be dropping to DDB
> and hanging (because the console is still in X mode) as you
> indicated you think is happening.

Maybe that is the cause then, with ddb perhaps there is no real "kill" 
and the situation can be explained.


> That one can be tested by disabling ddb.onpanic
> 	( sysctl -w ddb.onpanic=0 )
> and doing the rust build again - if the kernel crashes, it
> will simply crash and reboot now.
>
> Or you could do the rust build from a wscons console,
> and not run X at all, and see what happens then, if it
> is dropping into DDB, you should see it happen, and be
> able to interact.

I did build rust by not runnign anything else, just left the ThinkPad 
there compiling.
rustc takes a tooooo long time (I hate it, but that is another story).
I checked from time to time memory usage and the process stayed from 
300MB up to 1.2GB... but no swap usage. th machine ghas 1.5GB of RAM


Riccardo