Replace the page hold queue, PQ_HOLD, by a new page flag, PG_UNHOLDFREE,

because the queue itself serves no purpose.  When a held page is freed,
inserting the page into the hold queue has the side effect of setting the
page's "queue" field to PQ_HOLD.  Later, when the page is unheld, it will
be freed because the "queue" field is PQ_HOLD.  In other words, PQ_HOLD is
used as a flag, not a queue.  So, this change replaces it with a flag.

To accomodate the new page flag, make the page's "flags" field wider and
"oflags" field narrower.

Reviewed by:	kib

1 files changed, 4 insertions, 5 deletions

diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index 8f5182f..d3c797d 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -308,7 +308,6 @@ vm_page_startup(vm_offset_t vaddr)
 		TAILQ_INIT(&vm_page_queues[i].pl);
 	vm_page_queues[PQ_INACTIVE].cnt = &cnt.v_inactive_count;
 	vm_page_queues[PQ_ACTIVE].cnt = &cnt.v_active_count;
-	vm_page_queues[PQ_HOLD].cnt = &cnt.v_active_count;
 
 	/*
 	 * Allocate memory for use when boot strapping the kernel memory
@@ -540,7 +539,7 @@ vm_page_unhold(vm_page_t mem)
 	vm_page_lock_assert(mem, MA_OWNED);
 	--mem->hold_count;
 	KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!"));
-	if (mem->hold_count == 0 && mem->queue == PQ_HOLD)
+	if (mem->hold_count == 0 && (mem->flags & PG_UNHOLDFREE) != 0)
 		vm_page_free_toq(mem);
 }
 
@@ -2042,9 +2041,9 @@ vm_page_free_toq(vm_page_t m)
 		panic("vm_page_free: freeing wired page %p", m);
 	if (m->hold_count != 0) {
 		m->flags &= ~PG_ZERO;
-		vm_page_lock_queues();
-		vm_page_enqueue(PQ_HOLD, m);
-		vm_page_unlock_queues();
+		KASSERT((m->flags & PG_UNHOLDFREE) == 0,
+		    ("vm_page_free: freeing PG_UNHOLDFREE page %p", m));
+		m->flags |= PG_UNHOLDFREE;
 	} else {
 		/*
 		 * Restore the default memory attribute to the page.