From owner-freebsd-current  Tue Sep 17 10:20:10 2002
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Date: Tue, 17 Sep 2002 10:20:03 -0700 (PDT)
From: Nate Lawson <nate@root.org>
To: Martin Blapp <mb@imp.ch>
Cc: current@freebsd.org, peter@freebsd.org
Subject: Re: Crashdumps available for download ... please help
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On Tue, 17 Sep 2002, Martin Blapp wrote:
> Hope this helps people. After I've disabled the secondlevel
> CPU cache, the panic is now always at the same place:
> 
> 0xc02fd315 is in pmap_remove_pages (/usr/src/sys/i386/i386/pmap.c:2941).
> 2936    #ifdef PMAP_REMOVE_PAGES_CURPROC_ONLY
> 2937                    pte = vtopte(pv->pv_va);
> 2938    #else
> 2939                    pte = pmap_pte_quick(pv->pv_pmap, pv->pv_va);
> 2940    #endif
> 2941                    tpte = *pte;
> 2942
> 2943                    if (tpte == 0) {
> 2944                            printf("TPTE at %p  IS ZERO @ VA %08x\n",
> 2945                                    pte, pv->pv_va);

Try building your kernel with "options PMAP_REMOVE_PAGES_CURPROC_ONLY" and
see if the panic goes away.  If that works, the problem is
pmap_pte_quick().

In looking at pmap_pte_quick, either it is wrong or line 2941 is wrong in
always dereferencing pte.  pmap_pte_quick can return NULL (well 0).  It
seems like pmap_pte_quick is wrong because vtopte() never returns NULL,
just (PTmap + i386_btop(va)) i.e. a valid base plus some offset.

-Nate
 
> Kernelfile:
> 
> http://people.freebsd.org/~mbr/crashes/kernel.debug.bz2 (8 Mb)
> 
> Kernelconfig:
> 
> http://people.freebsd.org/~mbr/crashes/kernel.CONFIG
> 
> Cores:
> 
> http://people.freebsd.org/~mbr/crashes/vmcore.1.bz2 (5 Mb)
> http://people.freebsd.org/~mbr/crashes/vmcore.2.bz2 (7 Mb)
> http://people.freebsd.org/~mbr/crashes/vmcore.3.bz2 (26 Mb)
> 
> Descriptions:
> 
> http://people.freebsd.org/~mbr/crashes/vmcore.1.txt
> http://people.freebsd.org/~mbr/crashes/vmcore.2.txt
> http://people.freebsd.org/~mbr/crashes/vmcore.3.txt
> 
> Martin
> 
> 
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