Remove the unused loan_count field and the related uvm logic. Most of

the page loaning code is already in the Attic.

ok kettenis@, beck@

11 files changed, 56 insertions, 394 deletions

diff --git a/sys/uvm/uvm_amap.c b/sys/uvm/uvm_amap.c
index 25f5ae1d86b..ef8e5058bf1 100644
--- a/sys/uvm/uvm_amap.c
+++ b/sys/uvm/uvm_amap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_amap.c,v 1.58 2014/12/23 04:56:47 tedu Exp $	*/
+/*	$OpenBSD: uvm_amap.c,v 1.59 2015/08/21 16:04:35 visa Exp $	*/
 /*	$NetBSD: uvm_amap.c,v 1.27 2000/11/25 06:27:59 chs Exp $	*/
 
 /*
@@ -613,8 +613,6 @@ amap_copy(struct vm_map *map, struct vm_map_entry *entry, int waitf,
  *	so we resolve the COW here.
  *
  * => assume parent's entry was wired, thus all pages are resident.
- * => assume pages that are loaned out (loan_count) are already mapped
- *	read-only in all maps, and thus no need for us to worry about them
  * => caller passes child's map/entry in to us
  * => XXXCDC: out of memory should cause fork to fail, but there is
  *	currently no easy way to do this (needs fix)
@@ -646,15 +644,10 @@ ReStart:
 			    " in anon %p", anon);
 
 		/*
-		 * if the anon ref count is one and the page is not loaned,
-		 * then we are safe (the child has exclusive access to the
-		 * page).  if the page is loaned, then it must already be
-		 * mapped read-only.
-		 *
-		 * we only need to get involved when these are not true.
-		 * [note: if loan_count == 0, then the anon must own the page]
+		 * if the anon ref count is one, we are safe (the child has
+		 * exclusive access to the page).
 		 */
-		if (anon->an_ref > 1 && pg->loan_count == 0) {
+		if (anon->an_ref > 1) {
 			/*
 			 * if the page is busy then we have to wait for
 			 * it and then restart.
diff --git a/sys/uvm/uvm_anon.c b/sys/uvm/uvm_anon.c
index 4cea58096f9..2b17264b6ee 100644
--- a/sys/uvm/uvm_anon.c
+++ b/sys/uvm/uvm_anon.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_anon.c,v 1.43 2014/12/23 04:56:47 tedu Exp $	*/
+/*	$OpenBSD: uvm_anon.c,v 1.44 2015/08/21 16:04:35 visa Exp $	*/
 /*	$NetBSD: uvm_anon.c,v 1.10 2000/11/25 06:27:59 chs Exp $	*/
 
 /*
@@ -86,47 +86,24 @@ uvm_anfree(struct vm_anon *anon)
 	pg = anon->an_page;
 
 	/*
-	 * if there is a resident page and it is loaned, then anon may not
-	 * own it.   call out to uvm_anon_lockpage() to ensure the real owner
- 	 * of the page has been identified and locked.
-	 */
-	if (pg && pg->loan_count)
-		pg = uvm_anon_lockloanpg(anon);
-
-	/*
 	 * if we have a resident page, we must dispose of it before freeing
 	 * the anon.
 	 */
 	if (pg) {
 		/*
-		 * if the page is owned by a uobject, then we must 
-		 * kill the loan on the page rather than free it.
+		 * if page is busy then we just mark it as released (who ever
+		 * has it busy must check for this when they wake up). if the
+		 * page is not busy then we can free it now.
 		 */
-		if (pg->uobject) {
-			uvm_lock_pageq();
-			KASSERT(pg->loan_count > 0);
-			pg->loan_count--;
-			pg->uanon = NULL;
-			uvm_unlock_pageq();
-		} else {
-			/*
-			 * page has no uobject, so we must be the owner of it.
-			 *
-			 * if page is busy then we just mark it as released
-			 * (who ever has it busy must check for this when they
-			 * wake up).    if the page is not busy then we can
-			 * free it now.
-			 */
-			if ((pg->pg_flags & PG_BUSY) != 0) {
-				/* tell them to dump it when done */
-				atomic_setbits_int(&pg->pg_flags, PG_RELEASED);
-				return;
-			} 
-			pmap_page_protect(pg, PROT_NONE);
-			uvm_lock_pageq();	/* lock out pagedaemon */
-			uvm_pagefree(pg);	/* bye bye */
-			uvm_unlock_pageq();	/* free the daemon */
-		}
+		if ((pg->pg_flags & PG_BUSY) != 0) {
+			/* tell them to dump it when done */
+			atomic_setbits_int(&pg->pg_flags, PG_RELEASED);
+			return;
+		} 
+		pmap_page_protect(pg, PROT_NONE);
+		uvm_lock_pageq();	/* lock out pagedaemon */
+		uvm_pagefree(pg);	/* bye bye */
+		uvm_unlock_pageq();	/* free the daemon */
 	}
 	if (pg == NULL && anon->an_swslot != 0) {
 		/* this page is no longer only in swap. */
@@ -162,50 +139,6 @@ uvm_anon_dropswap(struct vm_anon *anon)
 }
 
 /*
- * uvm_anon_lockloanpg: given a locked anon, lock its resident page
- *
- * => on return:
- *		 if there is a resident page:
- *			if it is ownerless, we take over as owner
- *		 we return the resident page (it can change during
- *		 this function)
- * => note that the only time an anon has an ownerless resident page
- *	is if the page was loaned from a uvm_object and the uvm_object
- *	disowned it
- * => this only needs to be called when you want to do an operation
- *	on an anon's resident page and that page has a non-zero loan
- *	count.
- */
-struct vm_page *
-uvm_anon_lockloanpg(struct vm_anon *anon)
-{
-	struct vm_page *pg;
-
-	/*
-	 * loop while we have a resident page that has a non-zero loan count.
-	 * if we successfully get our lock, we will "break" the loop.
-	 * note that the test for pg->loan_count is not protected -- this
-	 * may produce false positive results.   note that a false positive
-	 * result may cause us to do more work than we need to, but it will
-	 * not produce an incorrect result.
-	 */
-	while (((pg = anon->an_page) != NULL) && pg->loan_count != 0) {
-		/*
-		 * if page is un-owned [i.e. the object dropped its ownership],
-		 * then we can take over as owner!
-		 */
-		if (pg->uobject == NULL && (pg->pg_flags & PQ_ANON) == 0) {
-			uvm_lock_pageq();
-			atomic_setbits_int(&pg->pg_flags, PQ_ANON);
-			pg->loan_count--;	/* ... and drop our loan */
-			uvm_unlock_pageq();
-		}
-		break;
-	}
-	return(pg);
-}
-
-/*
  * fetch an anon's page.
  *
  * => returns TRUE if pagein was aborted due to lack of memory.
diff --git a/sys/uvm/uvm_anon.h b/sys/uvm/uvm_anon.h
index f0a5800f0df..894f5031dec 100644
--- a/sys/uvm/uvm_anon.h
+++ b/sys/uvm/uvm_anon.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_anon.h,v 1.18 2014/07/11 16:35:40 jsg Exp $	*/
+/*	$OpenBSD: uvm_anon.h,v 1.19 2015/08/21 16:04:35 visa Exp $	*/
 /*	$NetBSD: uvm_anon.h,v 1.13 2000/12/27 09:17:04 chs Exp $	*/
 
 /*
@@ -80,7 +80,6 @@ struct vm_aref {
 struct vm_anon	*uvm_analloc(void);
 void		 uvm_anfree(struct vm_anon *);
 void		 uvm_anon_init(void);
-struct vm_page	*uvm_anon_lockloanpg(struct vm_anon *);
 void		 uvm_anon_dropswap(struct vm_anon *);
 boolean_t	 uvm_anon_pagein(struct vm_anon *);
 #endif /* _KERNEL */
diff --git a/sys/uvm/uvm_aobj.c b/sys/uvm/uvm_aobj.c
index 09871fdcb34..0a6371048ce 100644
--- a/sys/uvm/uvm_aobj.c
+++ b/sys/uvm/uvm_aobj.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_aobj.c,v 1.79 2015/05/07 01:55:44 jsg Exp $	*/
+/*	$OpenBSD: uvm_aobj.c,v 1.80 2015/08/21 16:04:35 visa Exp $	*/
 /*	$NetBSD: uvm_aobj.c,v 1.39 2001/02/18 21:19:08 chs Exp $	*/
 
 /*
@@ -960,9 +960,8 @@ uao_flush(struct uvm_object *uobj, voff_t start, voff_t stop, int flags)
 			/* FALLTHROUGH */
 		case PGO_DEACTIVATE:
  deactivate_it:
-			/* skip the page if it's loaned or wired */
-			if (pp->loan_count != 0 ||
-			    pp->wire_count != 0)
+			/* skip the page if it's wired */
+			if (pp->wire_count != 0)
 				continue;
 
 			uvm_lock_pageq();
@@ -982,9 +981,8 @@ uao_flush(struct uvm_object *uobj, voff_t start, voff_t stop, int flags)
 			if (uobj->uo_refs > 1)
 				goto deactivate_it;
 
-			/* XXX skip the page if it's loaned or wired */
-			if (pp->loan_count != 0 ||
-			    pp->wire_count != 0)
+			/* XXX skip the page if it's wired */
+			if (pp->wire_count != 0)
 				continue;
 
 			/* zap all mappings for the page. */
diff --git a/sys/uvm/uvm_fault.c b/sys/uvm/uvm_fault.c
index 2e6807ab553..a9bf2889fb2 100644
--- a/sys/uvm/uvm_fault.c
+++ b/sys/uvm/uvm_fault.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_fault.c,v 1.84 2015/03/14 03:38:53 jsg Exp $	*/
+/*	$OpenBSD: uvm_fault.c,v 1.85 2015/08/21 16:04:35 visa Exp $	*/
 /*	$NetBSD: uvm_fault.c,v 1.51 2000/08/06 00:22:53 thorpej Exp $	*/
 
 /*
@@ -180,7 +180,7 @@ uvmfault_anonflush(struct vm_anon **anons, int n)
 		if (anons[lcv] == NULL)
 			continue;
 		pg = anons[lcv]->an_page;
-		if (pg && (pg->pg_flags & PG_BUSY) == 0 && pg->loan_count == 0) {
+		if (pg && (pg->pg_flags & PG_BUSY) == 0) {
 			uvm_lock_pageq();
 			if (pg->wire_count == 0) {
 				pmap_page_protect(pg, PROT_NONE);
@@ -258,8 +258,6 @@ uvmfault_amapcopy(struct uvm_faultinfo *ufi)
  * => we don't move the page on the queues [gets moved later]
  * => if we allocate a new page [we_own], it gets put on the queues.
  *    either way, the result is that the page is on the queues at return time
- * => for pages which are on loan from a uvm_object (and thus are not
- *    owned by the anon): if successful, we return with the owning object
  */
 int
 uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap,
@@ -283,25 +281,17 @@ uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap,
 		we_own = FALSE;		/* TRUE if we set PG_BUSY on a page */
 		pg = anon->an_page;
 
-		/*
-		 * if there is a resident page and it is loaned, then anon
-		 * may not own it.   call out to uvm_anon_lockpage() to ensure
-		 * the real owner of the page has been identified.
-		 */
-		if (pg && pg->loan_count)
-			pg = uvm_anon_lockloanpg(anon);
-
 		/* page there?   make sure it is not busy/released. */
 		if (pg) {
+			KASSERT(pg->pg_flags & PQ_ANON);
+			KASSERT(pg->uanon == anon);
+			
 			/*
-			 * at this point, if the page has a uobject [meaning
-			 * we have it on loan], then that uobject is locked
-			 * by us!   if the page is busy, we drop all the
-			 * locks (including uobject) and try again.
+			 * if the page is busy, we drop all the locks and
+			 * try again.
 			 */
-			if ((pg->pg_flags & (PG_BUSY|PG_RELEASED)) == 0) {
+			if ((pg->pg_flags & (PG_BUSY|PG_RELEASED)) == 0)
 				return (VM_PAGER_OK);
-			}
 			atomic_setbits_int(&pg->pg_flags, PG_WANTED);
 			uvmexp.fltpgwait++;
 
@@ -309,14 +299,8 @@ uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap,
 			 * the last unlock must be an atomic unlock+wait on
 			 * the owner of page
 			 */
-			if (pg->uobject) {	/* owner is uobject ? */
-				uvmfault_unlockall(ufi, amap, NULL, anon);
-				UVM_WAIT(pg, FALSE, "anonget1",0);
-			} else {
-				/* anon owns page */
-				uvmfault_unlockall(ufi, amap, NULL, NULL);
-				UVM_WAIT(pg, 0, "anonget2", 0);
-			}
+			uvmfault_unlockall(ufi, amap, NULL, NULL);
+			UVM_WAIT(pg, 0, "anonget2", 0);
 			/* ready to relock and try again */
 		} else {
 			/* no page, we must try and bring it in. */
@@ -694,8 +678,7 @@ ReFault:
 			continue;
 		}
 		anon = anons[lcv];
-		/* ignore loaned pages */
-		if (anon->an_page && anon->an_page->loan_count == 0 &&
+		if (anon->an_page &&
 		    (anon->an_page->pg_flags & (PG_RELEASED|PG_BUSY)) == 0) {
 			uvm_lock_pageq();
 			uvm_pageactivate(anon->an_page);	/* reactivate */
@@ -881,73 +864,6 @@ ReFault:
 #endif
 	}
 
-	/* uobj is non null if the page is on loan from an object (i.e. uobj) */
-	uobj = anon->an_page->uobject;
-
-	/* special handling for loaned pages */
-	if (anon->an_page->loan_count) {
-		if ((access_type & PROT_WRITE) == 0) {
-			/*
-			 * for read faults on loaned pages we just cap the
-			 * protection at read-only.
-			 */
-			enter_prot = enter_prot & ~PROT_WRITE;
-		} else {
-			/*
-			 * note that we can't allow writes into a loaned page!
-			 *
-			 * if we have a write fault on a loaned page in an
-			 * anon then we need to look at the anon's ref count.
-			 * if it is greater than one then we are going to do
-			 * a normal copy-on-write fault into a new anon (this
-			 * is not a problem).  however, if the reference count
-			 * is one (a case where we would normally allow a
-			 * write directly to the page) then we need to kill
-			 * the loan before we continue.
-			 */
-
-			/* >1 case is already ok */
-			if (anon->an_ref == 1) {
-				/* get new un-owned replacement page */
-				pg = uvm_pagealloc(NULL, 0, NULL, 0);
-				if (pg == NULL) {
-					uvmfault_unlockall(&ufi, amap, uobj,
-					    anon);
-					uvm_wait("flt_noram2");
-					goto ReFault;
-				}
-
-				/* copy data, kill loan */
-				/* copy old -> new */
-				uvm_pagecopy(anon->an_page, pg);
-
-				/* force reload */
-				pmap_page_protect(anon->an_page, PROT_NONE);
-				uvm_lock_pageq();	  /* KILL loan */
-				if (uobj)
-					/* if we were loaning */
-					anon->an_page->loan_count--;
-				anon->an_page->uanon = NULL;
-				/* in case we owned */
-				atomic_clearbits_int(
-				    &anon->an_page->pg_flags, PQ_ANON);
-				uvm_pageactivate(pg);
-				uvm_unlock_pageq();
-				if (uobj) {
-					uobj = NULL;
-				}
-
-				/* install new page in anon */
-				anon->an_page = pg;
-				pg->uanon = anon;
-				atomic_setbits_int(&pg->pg_flags, PQ_ANON);
-				atomic_clearbits_int(&pg->pg_flags,
-				    PG_BUSY|PG_FAKE);
-				UVM_PAGE_OWN(pg, NULL);
-			}     /* ref == 1 */
-		}       /* write fault */
-	}         /* loan count */
-
 	/*
 	 * if we are case 1B then we will need to allocate a new blank
 	 * anon to transfer the data into.   note that we have a lock
@@ -973,7 +889,7 @@ ReFault:
 		if (anon == NULL || pg == NULL) {
 			if (anon)
 				uvm_anfree(anon);
-			uvmfault_unlockall(&ufi, amap, uobj, oanon);
+			uvmfault_unlockall(&ufi, amap, NULL, oanon);
 			KASSERT(uvmexp.swpgonly <= uvmexp.swpages);
 			if (anon == NULL || uvmexp.swpgonly == uvmexp.swpages) {
 				uvmexp.fltnoanon++;
@@ -1025,7 +941,7 @@ ReFault:
 		 * We do, however, have to go through the ReFault path,
 		 * as the map may change while we're asleep.
 		 */
-		uvmfault_unlockall(&ufi, amap, uobj, oanon);
+		uvmfault_unlockall(&ufi, amap, NULL, oanon);
 		KASSERT(uvmexp.swpgonly <= uvmexp.swpages);
 		if (uvmexp.swpgonly == uvmexp.swpages) {
 			/* XXX instrumentation */
@@ -1057,7 +973,7 @@ ReFault:
 	uvm_unlock_pageq();
 
 	/* done case 1!  finish up by unlocking everything and returning success */
-	uvmfault_unlockall(&ufi, amap, uobj, oanon);
+	uvmfault_unlockall(&ufi, amap, NULL, oanon);
 	pmap_update(ufi.orig_map->pmap);
 	return (0);
 
@@ -1176,84 +1092,8 @@ Case2:
 		/* assert(uobjpage != PGO_DONTCARE) */
 
 		/*
-		 * we are faulting directly on the page.   be careful
-		 * about writing to loaned pages...
+		 * we are faulting directly on the page.
 		 */
-		if (uobjpage->loan_count) {
-
-			if ((access_type & PROT_WRITE) == 0) {
-				/* read fault: cap the protection at readonly */
-				/* cap! */
-				enter_prot = enter_prot & ~PROT_WRITE;
-			} else {
-				/* write fault: must break the loan here */
-				/* alloc new un-owned page */
-				pg = uvm_pagealloc(NULL, 0, NULL, 0);
-
-				if (pg == NULL) {
-					/*
-					 * drop ownership of page, it can't
-					 * be released
-					 */
-					if (uobjpage->pg_flags & PG_WANTED)
-						wakeup(uobjpage);
-					atomic_clearbits_int(
-					    &uobjpage->pg_flags,
-					    PG_BUSY|PG_WANTED);
-					UVM_PAGE_OWN(uobjpage, NULL);
-
-					uvm_lock_pageq();
-					/* activate: we will need it later */
-					uvm_pageactivate(uobjpage);
-
-					uvm_unlock_pageq();
-					uvmfault_unlockall(&ufi, amap, uobj,
-					  NULL);
-					uvmexp.fltnoram++;
-					uvm_wait("flt_noram4");
-					goto ReFault;
-				}
-
-				/*
-				 * copy the data from the old page to the new
-				 * one and clear the fake/clean flags on the
-				 * new page (keep it busy).  force a reload
-				 * of the old page by clearing it from all
-				 * pmaps.  then lock the page queues to
-				 * rename the pages.
-				 */
-				uvm_pagecopy(uobjpage, pg);	/* old -> new */
-				atomic_clearbits_int(&pg->pg_flags,
-				    PG_FAKE|PG_CLEAN);
-				pmap_page_protect(uobjpage, PROT_NONE);
-				if (uobjpage->pg_flags & PG_WANTED)
-					wakeup(uobjpage);
-				atomic_clearbits_int(&uobjpage->pg_flags,
-				    PG_BUSY|PG_WANTED);
-				UVM_PAGE_OWN(uobjpage, NULL);
-
-				uvm_lock_pageq();
-				uoff = uobjpage->offset;
-				/* remove old page */
-				uvm_pagerealloc(uobjpage, NULL, 0);
-
-				/*
-				 * at this point we have absolutely no
-				 * control over uobjpage
-				 */
-				/* install new page */
-				uvm_pagerealloc(pg, uobj, uoff);
-				uvm_unlock_pageq();
-
-				/*
-				 * done!  loan is broken and "pg" is
-				 * PG_BUSY.   it can now replace uobjpage.
-				 */
-
-				uobjpage = pg;
-
-			}		/* write fault case */
-		}		/* if loan_count */
 	} else {
 		/*
 		 * if we are going to promote the data to an anon we
diff --git a/sys/uvm/uvm_map.c b/sys/uvm/uvm_map.c
index 15ad44a21c9..c83a303febd 100644
--- a/sys/uvm/uvm_map.c
+++ b/sys/uvm/uvm_map.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_map.c,v 1.193 2015/08/19 12:23:25 visa Exp $	*/
+/*	$OpenBSD: uvm_map.c,v 1.194 2015/08/21 16:04:35 visa Exp $	*/
 /*	$NetBSD: uvm_map.c,v 1.86 2000/11/27 08:40:03 chs Exp $	*/
 
 /*
@@ -2940,8 +2940,8 @@ uvm_page_printit(pg, full, pr)
 	(*pr)("  flags=%b, vers=%d, wire_count=%d, pa=0x%llx\n",
 	    pg->pg_flags, page_flagbits, pg->pg_version, pg->wire_count,
 	    (long long)pg->phys_addr);
-	(*pr)("  uobject=%p, uanon=%p, offset=0x%llx loan_count=%d\n",
-	    pg->uobject, pg->uanon, (long long)pg->offset, pg->loan_count);
+	(*pr)("  uobject=%p, uanon=%p, offset=0x%llx\n",
+	    pg->uobject, pg->uanon, (long long)pg->offset);
 #if defined(UVM_PAGE_TRKOWN)
 	if (pg->pg_flags & PG_BUSY)
 		(*pr)("  owning process = %d, tag=%s",
@@ -4232,6 +4232,7 @@ uvm_map_clean(struct vm_map *map, vaddr_t start, vaddr_t end, int flags)
 			if (pg == NULL) {
 				continue;
 			}
+			KASSERT(pg->pg_flags & PQ_ANON);
 
 			switch (flags & (PGO_CLEANIT|PGO_FREE|PGO_DEACTIVATE)) {
 			/*
@@ -4244,24 +4245,12 @@ uvm_map_clean(struct vm_map *map, vaddr_t start, vaddr_t end, int flags)
 			case PGO_CLEANIT|PGO_DEACTIVATE:
 			case PGO_DEACTIVATE:
 deactivate_it:
-				/* skip the page if it's loaned or wired */
-				if (pg->loan_count != 0 ||
-				    pg->wire_count != 0) {
+				/* skip the page if it's wired */
+				if (pg->wire_count != 0)
 					break;
-				}
 
 				uvm_lock_pageq();
 
-				/*
-				 * skip the page if it's not actually owned
-				 * by the anon (may simply be loaned to the
-				 * anon).
-				 */
-				if ((pg->pg_flags & PQ_ANON) == 0) {
-					KASSERT(pg->uobject == NULL);
-					uvm_unlock_pageq();
-					break;
-				}
 				KASSERT(pg->uanon == anon);
 
 				/* zap all mappings for the page. */
diff --git a/sys/uvm/uvm_object.c b/sys/uvm/uvm_object.c
index cd0abfa74d4..6a666f15965 100644
--- a/sys/uvm/uvm_object.c
+++ b/sys/uvm/uvm_object.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_object.c,v 1.12 2014/12/17 19:42:15 tedu Exp $	*/
+/*	$OpenBSD: uvm_object.c,v 1.13 2015/08/21 16:04:35 visa Exp $	*/
 
 /*
  * Copyright (c) 2006 The NetBSD Foundation, Inc.
@@ -92,22 +92,6 @@ uvm_objwire(struct uvm_object *uobj, voff_t start, voff_t end,
 			KASSERT(pgs[i] != NULL);
 			KASSERT(!(pgs[i]->pg_flags & PG_RELEASED));
 
-#if 0
-			/*
-			 * Loan break
-			 */
-			if (pgs[i]->loan_count) {
-				while (pgs[i]->loan_count) {
-					pg = uvm_loanbreak(pgs[i]);
-					if (!pg) {
-						uvm_wait("uobjwirepg");
-						continue;
-					}
-				}
-				pgs[i] = pg;
-			}
-#endif
-
 			if (pgs[i]->pg_flags & PQ_AOBJ) {
 				atomic_clearbits_int(&pgs[i]->pg_flags,
 				    PG_CLEAN);
diff --git a/sys/uvm/uvm_page.c b/sys/uvm/uvm_page.c
index 4534980aaa9..4f9eabf7be7 100644
--- a/sys/uvm/uvm_page.c
+++ b/sys/uvm/uvm_page.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_page.c,v 1.140 2015/07/19 22:52:30 beck Exp $	*/
+/*	$OpenBSD: uvm_page.c,v 1.141 2015/08/21 16:04:35 visa Exp $	*/
 /*	$NetBSD: uvm_page.c,v 1.44 2000/11/27 08:40:04 chs Exp $	*/
 
 /*
@@ -967,7 +967,6 @@ uvm_pagerealloc(struct vm_page *pg, struct uvm_object *newobj, voff_t newoff)
 void
 uvm_pagefree(struct vm_page *pg)
 {
-	int saved_loan_count = pg->loan_count;
 	u_int flags_to_clear = 0;
 
 #ifdef DEBUG
@@ -983,45 +982,9 @@ uvm_pagefree(struct vm_page *pg)
 	 * if the page was an object page (and thus "TABLED"), remove it
 	 * from the object.
 	 */
-	if (pg->pg_flags & PG_TABLED) {
-		/*
-		 * if the object page is on loan we are going to drop ownership.
-		 * it is possible that an anon will take over as owner for this
-		 * page later on.   the anon will want a !PG_CLEAN page so that
-		 * it knows it needs to allocate swap if it wants to page the
-		 * page out.
-		 */
-
-		/* in case an anon takes over */
-		if (saved_loan_count)
-			atomic_clearbits_int(&pg->pg_flags, PG_CLEAN);
+	if (pg->pg_flags & PG_TABLED)
 		uvm_pageremove(pg);
 
-		/*
-		 * if our page was on loan, then we just lost control over it
-		 * (in fact, if it was loaned to an anon, the anon may have
-		 * already taken over ownership of the page by now and thus
-		 * changed the loan_count [e.g. in uvmfault_anonget()]) we just
-		 * return (when the last loan is dropped, then the page can be
-		 * freed by whatever was holding the last loan).
-		 */
-		if (saved_loan_count)
-			return;
-	} else if (saved_loan_count && pg->uanon) {
-		/*
-		 * if our page is owned by an anon and is loaned out to the
-		 * kernel then we just want to drop ownership and return.
-		 * the kernel must free the page when all its loans clear ...
-		 * note that the kernel can't change the loan status of our
-		 * page as long as we are holding PQ lock.
-		 */
-		atomic_clearbits_int(&pg->pg_flags, PQ_ANON);
-		pg->uanon->an_page = NULL;
-		pg->uanon = NULL;
-		return;
-	}
-	KASSERT(saved_loan_count == 0);
-
 	/* now remove the page from the queues */
 	if (pg->pg_flags & PQ_ACTIVE) {
 		TAILQ_REMOVE(&uvm.page_active, pg, pageq);
diff --git a/sys/uvm/uvm_page.h b/sys/uvm/uvm_page.h
index 32119e7f597..aaf03181c81 100644
--- a/sys/uvm/uvm_page.h
+++ b/sys/uvm/uvm_page.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_page.h,v 1.58 2015/04/22 03:48:52 dlg Exp $	*/
+/*	$OpenBSD: uvm_page.h,v 1.59 2015/08/21 16:04:35 visa Exp $	*/
 /*	$NetBSD: uvm_page.h,v 1.19 2000/12/28 08:24:55 chs Exp $	*/
 
 /* 
@@ -105,9 +105,6 @@ struct vm_page {
 	u_int			pg_version;	/* version count */
 	u_int			wire_count;	/* wired down map refs [P] */
 
-	u_int			loan_count;	/* number of active loans
-						 * to read: [P]
-						 * to modify: [P] */
 	paddr_t			phys_addr;	/* physical address of page */
 	psize_t			fpgsz;		/* free page range size */
 
diff --git a/sys/uvm/uvm_pdaemon.c b/sys/uvm/uvm_pdaemon.c
index 1e661a04e19..ea8961703e0 100644
--- a/sys/uvm/uvm_pdaemon.c
+++ b/sys/uvm/uvm_pdaemon.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_pdaemon.c,v 1.75 2014/12/17 19:42:15 tedu Exp $	*/
+/*	$OpenBSD: uvm_pdaemon.c,v 1.76 2015/08/21 16:04:35 visa Exp $	*/
 /*	$NetBSD: uvm_pdaemon.c,v 1.23 2000/08/20 10:24:14 bjh21 Exp $	*/
 
 /* 
@@ -419,31 +419,9 @@ uvmpd_scan_inactive(struct pglist *pglst)
 				continue;
 			}
 
-			/*
-			 * the only time we expect to see an ownerless page
-			 * (i.e. a page with no uobject and !PQ_ANON) is if an
-			 * anon has loaned a page from a uvm_object and the
-			 * uvm_object has dropped the ownership.  in that
-			 * case, the anon can "take over" the loaned page
-			 * and make it its own.
-			 */
-
-			/* is page part of an anon or ownerless ? */
-			if ((p->pg_flags & PQ_ANON) || p->uobject == NULL) {
+			if (p->pg_flags & PQ_ANON) {
 				anon = p->uanon;
 				KASSERT(anon != NULL);
-
-				/*
-				 * if the page is ownerless, claim it in the
-				 * name of "anon"!
-				 */
-				if ((p->pg_flags & PQ_ANON) == 0) {
-					KASSERT(p->loan_count > 0);
-					p->loan_count--;
-					atomic_setbits_int(&p->pg_flags,
-					    PQ_ANON);
-					/* anon now owns it */
-				}
 				if (p->pg_flags & PG_BUSY) {
 					uvmexp.pdbusy++;
 					/* someone else owns page, skip it */
@@ -872,25 +850,15 @@ uvmpd_scan(void)
 	     p != NULL && (inactive_shortage > 0 || swap_shortage > 0);
 	     p = nextpg) {
 		nextpg = TAILQ_NEXT(p, pageq);
+
+		/* skip this page if it's busy. */
 		if (p->pg_flags & PG_BUSY)
 			continue;
 
-		/* is page anon owned or ownerless? */
-		if ((p->pg_flags & PQ_ANON) || p->uobject == NULL) {
+		if (p->pg_flags & PQ_ANON)
 			KASSERT(p->uanon != NULL);
-
-			/* take over the page? */
-			if ((p->pg_flags & PQ_ANON) == 0) {
-				KASSERT(p->loan_count > 0);
-				p->loan_count--;
-				atomic_setbits_int(&p->pg_flags, PQ_ANON);
-			}
-		}
-
-		/* skip this page if it's busy. */
-		if ((p->pg_flags & PG_BUSY) != 0) {
-			continue;
-		}
+		else
+			KASSERT(p->uobject != NULL);
 
 		/*
 		 * if there's a shortage of swap, free any swap allocated
diff --git a/sys/uvm/uvm_pmemrange.c b/sys/uvm/uvm_pmemrange.c
index cee67c0a721..f4a86c9936d 100644
--- a/sys/uvm/uvm_pmemrange.c
+++ b/sys/uvm/uvm_pmemrange.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_pmemrange.c,v 1.47 2015/08/19 12:24:30 visa Exp $	*/
+/*	$OpenBSD: uvm_pmemrange.c,v 1.48 2015/08/21 16:04:35 visa Exp $	*/
 
 /*
  * Copyright (c) 2009, 2010 Ariane van der Steldt <ariane@stack.nl>
@@ -1244,12 +1244,10 @@ uvm_pmr_assertvalid(struct uvm_pmemrange *pmr)
 			/*
 			 * Free pages are:
 			 * - not wired
-			 * - not loaned
 			 * - have no vm_anon
 			 * - have no uvm_object
 			 */
 			KASSERT(i[lcv].wire_count == 0);
-			KASSERT(i[lcv].loan_count == 0);
 			KASSERT(i[lcv].uanon == (void*)0xdeadbeef ||
 			    i[lcv].uanon == NULL);
 			KASSERT(i[lcv].uobject == (void*)0xdeadbeef ||