panic: uvm_unmap_remove: has mapping

[Hans Rosenfeld <rosenfeld%grumpf.hope-2000.org@localhost>]

When booting a yesterdays -current GENERIC kernel with DEBUG enabled on
my 4k90, the system panics:

root on sd0a dumps on sd0b
init: copying out path `/sbin/init' 11
panic: uvm_unmap_remove: has mapping 
Stopped in pid 1.1 (init) at    netbsd:panic+0x172:     brb panic+0x1f2
db> trace
panic: uvm_unmap_remove: has mapping
Stack traceback :
0x8c034df8: panic+0x172(0x803273b1)
0x8c034e28: 
uvm_unmap_remove+0x35c(0x87e54e8c,0x7f7fe000,0x7f7ff000,0x8c034ed8,0,0)
0x8c034ea4: sys_munmap+0xa2(0x87e96b60,0x8c034f40,0x8c034f68)
0x8c034ef8: syscall+0x1ff(0x8c034fb4) 

I recall that I've seen this problem two years ago on 3.0, caused by a
bug in pmap_extract(). I sent a patch to fix this bug, but it has never
been committed (http://mail-index.netbsd.org/port-vax/2006/03/09/0004.html).
Applying that patch to -current will make the panic occur later:

root on sd0a dumps on sd0b
init: copying out path `/sbin/init' 11
Wed Marpanic:  uvm_unmap_remove: has mapping 
5Stopped in pid 4.1 (date) at    netbsd:panic+0x172:     brb panic+0x1f2
db> trace
panic: uvm_unmap_remove: has mapping
Stack traceback :
0x8c044d1c: panic+0x172(0x803273d1)
0x8c044d4c: uvm_unmap_remove+0x35c(0x87e54d04,0,0x80000000,0x8c044e00,0,0)
0x8c044dc8: uvmspace_free+0xb8(0x87e54d04)
0x8c044e10: uvm_proc_exit+0x81(0x87e599d8)
0x8c044e3c: exit1+0x2f2(0x87e96020,0)
0x8c044ed0: exit1+0x0(0x87e96020,0x8c044f40,0x8c044f68)
0x8c044ef8: syscall+0x1ff(0x8c044fb4)

I think the original patch is still valid and should be committed, but
there is some other problem somewhere causing the system to panic
anyway.

I would like to get some feedback this time, especially on whether this
is reproducable by others.


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