From bbf4b0c0bf425448cec9b0e1e4f1898f7f07fd38 Mon Sep 17 00:00:00 2001
From: kmacy <kmacy@FreeBSD.org>
Date: Fri, 30 Apr 2010 21:20:14 +0000
Subject: [PATCH] - acquire the page lock in vm_contig_launder_page before
 checking page fields - release page queue lock before calling
 vm_pageout_flush

---
 sys/vm/vm_contig.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/sys/vm/vm_contig.c b/sys/vm/vm_contig.c
index 7220055cd259..2c8b8b11c251 100644
--- a/sys/vm/vm_contig.c
+++ b/sys/vm/vm_contig.c
@@ -96,30 +96,33 @@ vm_contig_launder_page(vm_page_t m, vm_page_t *next)
 	vm_page_t m_tmp;
 	struct vnode *vp;
 	struct mount *mp;
-	int vfslocked;
+	int vfslocked, dirty;
 
-	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
+	vm_page_lock(m);
+	vm_page_lock_queues();
 	object = m->object;
 	if (!VM_OBJECT_TRYLOCK(object) &&
 	    !vm_pageout_fallback_object_lock(m, next)) {
 		VM_OBJECT_UNLOCK(object);
+		vm_page_unlock_queues();
+		vm_page_unlock(m);
 		return (EAGAIN);
 	}
 	if (vm_page_sleep_if_busy(m, TRUE, "vpctw0")) {
 		VM_OBJECT_UNLOCK(object);
-		vm_page_lock_queues();
 		return (EBUSY);
 	}
 	vm_page_test_dirty(m);
 	if (m->dirty == 0 && m->hold_count == 0)
 		pmap_remove_all(m);
-	if (m->dirty) {
+	if ((dirty = m->dirty) != 0) {
+		vm_page_unlock_queues();
+		vm_page_unlock(m);
 		if ((object->flags & OBJ_DEAD) != 0) {
 			VM_OBJECT_UNLOCK(object);
 			return (EAGAIN);
 		}
 		if (object->type == OBJT_VNODE) {
-			vm_page_unlock_queues();
 			vp = object->handle;
 			vm_object_reference_locked(object);
 			VM_OBJECT_UNLOCK(object);
@@ -133,7 +136,6 @@ vm_contig_launder_page(vm_page_t m, vm_page_t *next)
 			VFS_UNLOCK_GIANT(vfslocked);
 			vm_object_deallocate(object);
 			vn_finished_write(mp);
-			vm_page_lock_queues();
 			return (0);
 		} else if (object->type == OBJT_SWAP ||
 			   object->type == OBJT_DEFAULT) {
@@ -144,6 +146,11 @@ vm_contig_launder_page(vm_page_t m, vm_page_t *next)
 		}
 	} else if (m->hold_count == 0)
 		vm_page_cache(m);
+
+	if (dirty == 0) {
+		vm_page_unlock_queues();
+		vm_page_unlock(m);
+	}
 	VM_OBJECT_UNLOCK(object);
 	return (0);
 }
@@ -162,7 +169,9 @@ vm_contig_launder(int queue)
 
 		KASSERT(VM_PAGE_INQUEUE2(m, queue),
 		    ("vm_contig_launder: page %p's queue is not %d", m, queue));
+		vm_page_unlock_queues();
 		error = vm_contig_launder_page(m, &next);
+		vm_page_lock_queues();
 		if (error == 0)
 			return (TRUE);
 		if (error == EBUSY)