From e35395ce217e8a12afa0c45d694be4575016ea31 Mon Sep 17 00:00:00 2001
From: Alan Cox <alc@FreeBSD.org>
Date: Thu, 20 Dec 2007 22:45:54 +0000
Subject: [PATCH] Modify vm_phys_unfree_page() so that it no longer requires
 the given page to be in the free lists.  Instead, it now returns TRUE if it
 removed the page from the free lists and FALSE if the page was not in the
 free lists.

This change is required to support superpage reservations.  Specifically,
once reservations are introduced, a cached page can either be in the
free lists or a reservation.
---
 sys/vm/vm_page.c |  7 +++++--
 sys/vm/vm_phys.c | 17 ++++++++++-------
 sys/vm/vm_phys.h |  5 ++++-
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index 4e684102d414..622f5fdee9ab 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -1026,8 +1026,11 @@ vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req)
 				mtx_unlock(&vm_page_queue_free_mtx);
 				return (NULL);
 			}
-			vm_phys_unfree_page(m);
-			vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m, 0);
+			if (vm_phys_unfree_page(m))
+				vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m, 0);
+			else
+				panic("vm_page_alloc: cache page %p is missing"
+				    " from the free queue", m);
 		} else if ((req & VM_ALLOC_IFCACHED) != 0) {
 			mtx_unlock(&vm_page_queue_free_mtx);
 			return (NULL);
diff --git a/sys/vm/vm_phys.c b/sys/vm/vm_phys.c
index 0fb685eb237d..a57304b46460 100644
--- a/sys/vm/vm_phys.c
+++ b/sys/vm/vm_phys.c
@@ -468,7 +468,7 @@ vm_phys_set_pool(int pool, vm_page_t m, int order)
  *
  * The free page queues must be locked.
  */
-void
+boolean_t
 vm_phys_unfree_page(vm_page_t m)
 {
 	struct vm_freelist *fl;
@@ -489,13 +489,15 @@ vm_phys_unfree_page(vm_page_t m)
 	    order < VM_NFREEORDER - 1; ) {
 		order++;
 		pa = m->phys_addr & (~(vm_paddr_t)0 << (PAGE_SHIFT + order));
-		KASSERT(pa >= seg->start && pa < seg->end,
-		    ("vm_phys_unfree_page: paddr %#jx is not within segment %p",
-		    (uintmax_t)pa, seg));
-		m_set = &seg->first_page[atop(pa - seg->start)];
+		if (pa >= seg->start && pa < seg->end)
+			m_set = &seg->first_page[atop(pa - seg->start)];
+		else
+			return (FALSE);
 	}
-	KASSERT(m_set->order >= order, ("vm_phys_unfree_page: page %p's order"
-	    " (%d) is less than expected (%d)", m_set, m_set->order, order));
+	if (m_set->order < order)
+		return (FALSE);
+	if (m_set->order == VM_NFREEORDER)
+		return (FALSE);
 	KASSERT(m_set->order < VM_NFREEORDER,
 	    ("vm_phys_unfree_page: page %p has unexpected order %d",
 	    m_set, m_set->order));
@@ -525,6 +527,7 @@ vm_phys_unfree_page(vm_page_t m)
 		fl[order].lcnt++;
 	}
 	KASSERT(m_set == m, ("vm_phys_unfree_page: fatal inconsistency"));
+	return (TRUE);
 }
 
 /*
diff --git a/sys/vm/vm_phys.h b/sys/vm/vm_phys.h
index 3e35f9b2cb18..0e012c322973 100644
--- a/sys/vm/vm_phys.h
+++ b/sys/vm/vm_phys.h
@@ -38,6 +38,8 @@
 #ifndef	_VM_PHYS_H_
 #define	_VM_PHYS_H_
 
+#ifdef _KERNEL
+
 void vm_phys_add_page(vm_paddr_t pa);
 vm_page_t vm_phys_alloc_contig(unsigned long npages,
     vm_paddr_t low, vm_paddr_t high,
@@ -47,7 +49,8 @@ vm_paddr_t vm_phys_bootstrap_alloc(vm_size_t size, unsigned long alignment);
 void vm_phys_free_pages(vm_page_t m, int order);
 void vm_phys_init(void);
 void vm_phys_set_pool(int pool, vm_page_t m, int order);
-void vm_phys_unfree_page(vm_page_t m);
+boolean_t vm_phys_unfree_page(vm_page_t m);
 boolean_t vm_phys_zero_pages_idle(void);
 
+#endif	/* _KERNEL */
 #endif	/* !_VM_PHYS_H_ */