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Date:      Wed, 06 Jun 2001 09:57:09 -0700 (PDT)
From:      John Baldwin <jhb@FreeBSD.org>
To:        Andrew Gallatin <gallatin@cs.duke.edu>
Cc:        Freebsd-alpha@FreeBSD.org, alfred@FreeBSD.org, obrien@FreeBSD.org
Subject:   Re: -current kernel still considered dangerous
Message-ID:  <XFMail.010606095709.jhb@FreeBSD.org>
In-Reply-To: <15134.14841.825808.882824@grasshopper.cs.duke.edu>

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On 06-Jun-01 Andrew Gallatin wrote:
> 
> David O'Brien writes:
>  > On Tue, Jun 05, 2001 at 05:48:08PM -0700, David O'Brien wrote:
>  > > On Tue, Jun 05, 2001 at 08:19:21PM -0400, Andrew Gallatin wrote:
>  > > > Its almost certainly a module loaded after boot, since the address
>  > > > does not lie in K0SEG.  Could this be the linulator running ldconfig?
>  > 
>  > I am going to go with osf1 compat module.  Running the dnetc binary
>  > triggers the panic.  The dnetc installation that I have can be found at
>  > http://people.freebsd.org/~obrien/dnetc-axp-panics.tar.gz
>  > 
>  > Since kgdb is hitting "heuristic-fence-post", how should I proceed in
>  > debugging this?
> 
> 
> 
> I just built a kernel statically & found it. Apparently, the vm_mtx
> must be held around vm_map_find(), vm_map_findspace(), and
> vm_map_lookup_entry(), and probably others. 

For now, yes.  In theory they perhaps shouldn't require it.  *sigh*  The vm
locking isn't done yet unfortunately.

> Is there any documentation what the locking requirements of various
> vm functions are now? I tested osf1 after my initial set of commits to catch
> alpha up to x86, but an assert must have been added since then.

Not really, and it is in a state of flux right now.  On my todo list is to
change the vm_map's to be locked by a sx lock, and once that is done I will
change those mtx_assert's to simply require the sx lock rather than the vm_mtx
lock.  However, I'm still not sure how vm_page's will be locked.  vm_object's
will probably have their own mutex or sx lock though.

-- 

John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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