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To: starkhome!gene@sbstark.cs.sunysb.edu (Gene Stark)
cc: current@FreeBSD.org, dyson@Root.COM
Subject: Re: Page fault panics during make world in -current 
In-reply-to: Your message of "Mon, 06 Mar 95 08:46:58 EST."
             <199503061346.IAA03940@starkhome.cs.sunysb.edu> 
From: David Greenman <davidg@Root.COM>
Reply-To: davidg@Root.COM
Date: Mon, 06 Mar 1995 07:20:22 -0800
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>In vfs_bio.c, line 758:
>
>	for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
>		int mask;
>
>-->		m = vm_page_lookup(obj, trunc_page(toff + off));
>		if (!m)
>			return 0;
>		if (vm_page_is_valid(m, toff + off, tinc) == 0)
>			return 0;
>	}
>
>The VM object obj is not locked, contrary to the comment preceding
>the definition of vm_page_lookup().  Potentially a problem?

   Object locking in uniprocessor systems is a NOP. If you look at the
definition of vm_object_lock, you'll see that it is defined as "simple_lock".
If you look at the definition of simple_lock, you'll see that it is nothing.
The missing object locks are an oversight...but not a problem.

-DG