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Date: Tue, 18 Jun 1996 08:16:00 +0200 (MET DST)
From: Juergen Lock <nox@jelal.hb.north.de>
Message-Id: <199606180616.IAA10166@saturn.hb.north.de>
To: davidg@Root.COM
Subject: Re: Trap 12/supervisor read, page not present
In-Reply-To: <199606171905.MAA00274@Root.COM>
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Cc: stable@freebsd.org
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In article <199606171905.MAA00274@Root.COM> you write:
>>Ok, I'm now getting detectable panics again (two panic/dumps, one
>>mystery reboot).  Seems like I've been switched to another common
>>VM problem: "invalid kernel page directory".
>>
>>Here are the two panics and backtraces:
>>kernel page directory invalid pdir=0x1beb023, va=0xefbfe000
>>panic: invalid kernel page directory
>>
>...
>>#2  0xf0192c4b in pmap_enter (pmap=0xf121f46c, va=4022329344, pa=44859392, 
>>    prot=7 '\a', wired=1) at ../../i386/i386/pmap.c:1184
>>#3  0xf017e2c5 in vm_fault (map=0xf121f400, vaddr=4022329344, 
>>    fault_type=7 '\a', change_wiring=1) at ../../vm/vm_fault.c:840
>>#4  0xf017e4d4 in vm_fault_wire (map=0xf121f400, start=4022329344, 
>>    end=4022337536) at ../../vm/vm_fault.c:919
>>#5  0xf0180b76 in vm_map_pageable (map=0xf121f400, start=4022329344, 
>>    end=4022337536, new_pageable=0) at ../../vm/vm_map.c:1401
>>#6  0xf017eda6 in vm_fork (p1=0xf12ef100, p2=0xf1335600, isvfork=0)
>>    at ../../vm/vm_glue.c:227
>...
>
>    Like I said, this is a "known" problem. What I don't understand is why you
>see it happen so often. It takes literally *months* of heavy system activity
>for me to reproduce this sometimes, which is why it has taken so long to fix
>it. We'll be looking at this problem again this week, but I can give no

Hmm.  im not deep enough inside the vm code to take a guess whether
it may be related or not but, i just made a new -stable kernel again
(now ctm-cvs-cur 2130) and the hold count problem (kern/1195) is
still there.  system just booted, otherwise completely idle except for
a few xterms and a xperfmon:  after having written stables /usr/obj this
time i have 21 of those (DIAGNOSTIC-panic-patched-into-printf, see PR)
messages on the xconsole...

find obj | afio -G 2 -o -v -f -b 5120 -c 1000 -s 100000x -Z /dev/nrst0
(this was the test.  CPU 486dx100, tape Wangtek 525ES, PCI NCR SCSI.)

 ATB and sorry if this is old news and of no use
	Juergen

PS: is the Root.COM a real address?  i cant nslookup right now
(still no flat rates in germany), therefore cc'd to the list...