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Subject: Re: repeatable panic on pageout with 945GM
To: Konstantin Belousov <kostikbel@gmail.com>, Matthew Macy <mmacy@nextbsd.org>
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 <20160604174745.GB38613@kib.kiev.ua>
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From: Michael Butler <imb@protected-networks.net>
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On 06/04/16 13:47, Konstantin Belousov wrote:

 [ .. snip .. ]

> I believe that this is a bug in amd64 pmap. Fictitious pages are not
> promoted, in particular, the pv_table array does not span over the
> dynamically registered fictitious ranges. As result, pa_to_pvh() returns
> garbage and pvh must not be accessed in the case of 'small_mappings' in
> several pmap functions.  It is typically not accessed, except in case
> when we have to drop and reacquire pv lock, to avoid LOR with pmap.
> 
> i386 does not have the issue, due to pvh_global_lock.
> 
> Below is the supposed fix (not tested).

 [ .. snip .. ]

Is this something I should test and, should it not introduce any other
issues, might get committed?

	imb