Re: kern/45361: Consistent kernel panic when building qemu in amd64

[Julio Merino <jmmv%NetBSD.org@localhost>]

On 9/12/11 4:40 PM, David Holland wrote:
> The following reply was made to PR kern/45361; it has been noted by GNATS.
>
>   Can you at least extract a non-garbled stack trace?

This is all I could get from a new kernel with 
DEBUG+LOCKDEBUG+DIAGNOSTIC in it, which does not seem that much helpful...

First, these messages popped in /var/log/messages after a first crash:

pmap_kenter_pa: mapping already present
pmap_kenter_pa: mapping already present
uvm_fault(0xffff800048c9ed00, 0x0, 1) -> e
pmap_kenter_pa: mapping already present
fatal page faultpmap_kenter_pa: mapping already present
in supervisor mode
pmap_kenter_pa: mapping already present
trap type 6 code 0 rip ffffffff80709c2b cs 8 rflags 10297 cr2  20 cpl 6 
rsp ffff800048ae4990
panic: trap
cpu1: Begin traceback...
startlwp() at netbsd:startlwp
alltraps() at netbsd:alltraps+0xa2
kevent1() at netbsd:kevent1+0x2ac
WARNING: SPL NOT LOWERED ON SYSCALL 16384 3 EXIT f6f308es0y s6_
__kevent50() at netbsd:sys___kevent50+0x33
WARNING: SPL NOT LOWERED ON SYSCALL 16384 3 EXIT f6f308e0 6
syscall() at netbsdW:AsRyNsIcNaGl:l +S0PxLa cN
OT LOWERED ON SYSCALL 16384 3 EXIT f6f308e0 6
cpu1: End traceback...

dumping to dev 0,1 offset 2025
dump WARNING: SPL NOT LOWERED ON SYSCALL 16384 3 EXIT f6f308e0 6

-----

And then, I set ddb.onpanic=1 and retried the test, getting the 
following crash and subsequent backtrace:

pmap_kenter_pa: mapping already present
pmap_kenter_pa: mapping already present
uvm_fault(0xffff800048c9bd00, 0x0, 1) -> e
pmap_kenter_pa: mapping already present
fatal page faultpmap_kenter_pa: mapping already present
 in supervisor mode
pmap_kenter_pa: mapping already present
trap type 6 code 0 rip ffffffff80709c2b cs 8 rflags 10297 cr2  24 cpl 6 
rsp ffff800048af3990
kernel: page fault trap, code=0
Stopped in pid 221.1 (syslogd) at     netbsd:pool_cache_put_paddr+0x52: 
cmpq 20(%r15),%rbx

ddb> bt
pool_cache_put_paddr() at netbsd:pool_cache_put_paddr+0x52
kevent1() at netbsd:kevent1+0x2ac
sys___kevent50() at netbsd:sys___kevent50+0x33
syscall() at netbsd:syscall+0xac