HEAD in dubious state after 254141

I'm in the process of reverting 254150 and 254141.  I think the changes in 
254141 were from an old tree that wasn't updated for the changes in 254138 and 
I don't seen an obvious way to fix 254141, so until Attilio can redo 254141 
I'm going to revert these.

-- 
John Baldwin

attached mail follows:

On Friday, August 09, 2013 12:43:50 pm David E. O'Brien wrote:
> Author: obrien
> Date: Fri Aug  9 16:43:50 2013
> New Revision: 254150
> URL: http://svnweb.freebsd.org/changeset/base/254150
> 
> Log:
>   Add missing 'VPO_BUSY' from r254141 to fix kernel build break.
> 
> Modified:
>   head/sys/vm/vm_page.h

This can't possibly be correct as r254138 just removed this flag.  If it isn't 
obvious how to fix the uses added back in r254141, then r254141 should be 
reverted instead.

Hmm, looking at the relevant bits of r254141, it doesn't look obvious:

+       /* Detach the old page from the resident tailq. */
+       TAILQ_REMOVE(&object->memq, mold, listq);
+       vm_page_lock(mold);
+       if (mold->oflags & VPO_BUSY) {
+               mold->oflags &= ~VPO_BUSY;
+               vm_page_flash(mold);
+       }

Since nothing is setting this flag, this can't possibly work correctly 
currently.  I wouldn't boot a top-of-tree kernel right now. :(

-- 
John Baldwin