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Date:      Thu, 4 Feb 1999 09:49:50 -0800 (PST)
From:      Matthew Dillon <dillon@apollo.backplane.com>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        Stephen McKay <syssgm@detir.qld.gov.au>, freebsd-current@FreeBSD.ORG, syssgm@detir.qld.gov.au
Subject:   Re: panic: vm_object_qcollapse(): object mismatch
Message-ID:  <199902041749.JAA89484@apollo.backplane.com>
References:  <199902041300.XAA10590@nymph.detir.qld.gov.au> <199902041726.JAA88650@apollo.backplane.com>

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    I introduced this bug in 1.139 when I added the KASSERT().  Bleh.
    However, the code still needs to be protected at splbio().  And so I've
    committed.

					    -Matt
	
:    Hmmm.  This looks like an out-an-out bug to me.  The assertion is wrong.
:    It's scanning the backing_object and asserting that the pages in the
:    backing object are associated with object rather then backing_object.
:
:    This section of code only runs when paging is in progress on a 
:    collapseable object AND there are also idle pages in that object.
:    The collapse condition is probably due to an exiting process ( typical
:    in a buildworld ).
:
:    ( from vm/vm_object.c )
:                /*
:                 * busy the page and move it from the backing store to the
:                 * parent object.
:                 */
:
:                vm_page_busy(p);
:
:                KASSERT(p->object == object, ("vm_object_qcollapse(): object mismatch"));
:		                    ^^^^^^^^^^
:					should be 'backing_object'
:
:    There is also an interrupt race.  Since paging can be in progress,
:    pages in the object can be ripped out from under it so we have to
:    run at splbio() in the loop.


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