Re: my simh-vax crashed: panic: pmap_enter on PG_SREF page

[Greg Oster <oster%netbsd.org@localhost>]

On 2023-12-20 19.42, Johnny Billquist wrote:
> Nothing concrete, except that that amount of memory did have issues in 
> the past. We hope it had been fixed, but maybe there is some kind of 
> issue with that much memory still? Could you try with less physical 
> memory? Like 128M?

I've seen this error at least 3 times now too.... this last time was 
with 256MB, but I'm pretty sure the first two were with just 64MB RAM.

Top looked like this when it died the last time:
CPU states: 97.6% user,  0.0% nice,  2.4% system,  0.0% interrupt,  0.0% 
idle
Memory: 141M Act, 69M Inact, 8464K Wired, 14M Exec, 33M File, 1964K Free
Swap: 1040M Total, 273M Used, 767M Free / Pools: 19M Used / Network:


Later...

Greg Oster

> On 2023-12-21 01:46, matthew green wrote:
> > because we can't have only nice things this season, my simh crashed
> > while building netbsd.
> >
> > this was a couple of days ago -current, built on amd64, building the
> > same source tree in simh-vax.
> >
> > db> bt
> > panic: pmap_enter on PG_SREF page
> > Stack traceback :
> > 0x94ba9c40: vpanic+0x179(0x802a0a35,0x94ba9cd8)
> > 0x94ba9c60: vprintf+0x0(0x802a0a35)
> > 0x94ba9c8c: pmap_enter+0x60a(0x8e8aec00,0x74a00000,0x2bdb000,0x3,0x21)
> > 0x94ba9cf4: 
> > uvm_fault_lower_enter+0x57(0x94ba9df4,0x94ba9e10,0,0x838cc420,0x80a26d18)
> > 0x94ba9d3c: uvm_fault_internal+0xd02(0x8cda5e00,0x74a00000,0x1,0)
> > 0x94ba9ebc: trap+0x148(0x94ba9fb4)
> > db> ps
> > PID    LID S CPU     FLAGS       STRUCT LWP *               NAME WAIT
> > 17504>17504 7   0     40000           8d400800            cc1plus
> >
> > so it was a cc1plus processing a trap, and doing what appears to be
> > re-mapping a page previously mapped with pmap_kenter_pa() (the only
> > way PG_SREF should be set.)
> >
> > this is a valid assert -- if it's been pmap_kenter_pa()'d it should
> > never be otherwise managed in kernel or userspace.
> >
> > any one have an idea what is up?  i have ddb still for now.  this
> > system is a 256mb microvax3900 instance in open-simh latest pkgsrc.
> >
> > thanks.
> >
> >
> > .mrg.