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Date:      Tue, 2 Mar 1999 18:16:50 -0500 (EST)
From:      Brian Feldman <green@unixhelp.org>
To:        Alan Cox <alc@cs.rice.edu>
Cc:        Bruce Evans <bde@zeta.org.au>, current@FreeBSD.ORG
Subject:   Re: lockmgr panic with mmap()
Message-ID:  <Pine.BSF.4.05.9903021816130.9317-100000@janus.syracuse.net>
In-Reply-To: <19990302113704.B90473@nonpc.cs.rice.edu>

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On Tue, 2 Mar 1999, Alan Cox wrote:

> On Tue, Mar 02, 1999 at 10:41:46PM +1100, Bruce Evans wrote:
> > 
> > Doesn't it modify the map indirectly vi subyte()?  I think it wants
> > to prevent modifications, but this is impossible.
> > 
> 
> Bear with me, I'll have to split some hairs...
> 
> We're only interested in whether mincore directly changes the vm_map,
> literally modifying a vm_map_entry, etc.  subyte is writing to memory,
> not a vm_map_entry.  subyte is only indirectly changing the map
> because a page fault occurs.  That page fault *is* (frequently) changing
> the map, and we're deadlocking when it attempts to acquire the write lock
> on the map.
> 
> Basically, what I believe that you suggested yesterday, that mincore
> release the lock around the subyte is correct.  Code will
> appear shortly...

Where exactly does thrd_sleep come in, since that's where the program locks
up now? Can't be killed, of course...

> 
> Alan
> 
> 
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