diff --git a/fs/lustre/include/lustre_dlm.h b/fs/lustre/include/lustre_dlm.h
index fd9b0f8..3417661 100644
--- a/fs/lustre/include/lustre_dlm.h
+++ b/fs/lustre/include/lustre_dlm.h
@@ -591,11 +591,6 @@ struct ldlm_lock {
 	 */
 	struct portals_handle		l_handle;
 	/**
-	 * Internal spinlock protects l_resource.  We should hold this lock
-	 * first before taking res_lock.
-	 */
-	spinlock_t			l_lock;
-	/**
 	 * Pointer to actual resource this lock is in.
 	 * ldlm_lock_change_resource() can change this.
 	 */
diff --git a/fs/lustre/ldlm/l_lock.c b/fs/lustre/ldlm/l_lock.c
index 296259a..0ba4942 100644
--- a/fs/lustre/ldlm/l_lock.c
+++ b/fs/lustre/ldlm/l_lock.c
@@ -45,15 +45,21 @@
  * being an atomic operation.
  */
 struct ldlm_resource *lock_res_and_lock(struct ldlm_lock *lock)
-				__acquires(&lock->l_lock)
 				__acquires(&lock->l_resource->lr_lock)
 {
-	spin_lock(&lock->l_lock);
+	struct ldlm_resource *res;
 
-	lock_res(lock->l_resource);
-
-	ldlm_set_res_locked(lock);
-	return lock->l_resource;
+	rcu_read_lock();
+	while (1) {
+		res = rcu_dereference(lock->l_resource);
+		lock_res(res);
+		if (res == lock->l_resource) {
+			ldlm_set_res_locked(lock);
+			rcu_read_unlock();
+			return res;
+		}
+		unlock_res(res);
+	}
 }
 EXPORT_SYMBOL(lock_res_and_lock);
 
@@ -62,12 +68,10 @@ struct ldlm_resource *lock_res_and_lock(struct ldlm_lock *lock)
  */
 void unlock_res_and_lock(struct ldlm_lock *lock)
 		__releases(&lock->l_resource->lr_lock)
-		__releases(&lock->l_lock)
 {
 	/* on server-side resource of lock doesn't change */
 	ldlm_clear_res_locked(lock);
 
 	unlock_res(lock->l_resource);
-	spin_unlock(&lock->l_lock);
 }
 EXPORT_SYMBOL(unlock_res_and_lock);
diff --git a/fs/lustre/ldlm/ldlm_lock.c b/fs/lustre/ldlm/ldlm_lock.c
index 5ac7723..e62dad1 100644
--- a/fs/lustre/ldlm/ldlm_lock.c
+++ b/fs/lustre/ldlm/ldlm_lock.c
@@ -383,7 +383,6 @@ static struct ldlm_lock *ldlm_lock_new(struct ldlm_resource *resource)
 	if (!lock)
 		return NULL;
 
-	spin_lock_init(&lock->l_lock);
 	lock->l_resource = resource;
 	lu_ref_add(&resource->lr_reference, "lock", lock);
 
@@ -452,12 +451,13 @@ int ldlm_lock_change_resource(struct ldlm_namespace *ns, struct ldlm_lock *lock,
 
 	lu_ref_add(&newres->lr_reference, "lock", lock);
 	/*
-	 * To flip the lock from the old to the new resource, lock, oldres and
-	 * newres have to be locked. Resource spin-locks are nested within
-	 * lock->l_lock, and are taken in the memory address order to avoid
-	 * dead-locks.
+	 * To flip the lock from the old to the new resource, oldres
+	 * and newres have to be locked. Resource spin-locks are taken
+	 * in the memory address order to avoid dead-locks.
+	 * As this is the only circumstance where ->l_resource
+	 * can change, and this cannot race with itself, it is safe
+	 * to access lock->l_resource without being careful about locking.
 	 */
-	spin_lock(&lock->l_lock);
 	oldres = lock->l_resource;
 	if (oldres < newres) {
 		lock_res(oldres);
@@ -468,9 +468,9 @@ int ldlm_lock_change_resource(struct ldlm_namespace *ns, struct ldlm_lock *lock,
 	}
 	LASSERT(memcmp(new_resid, &oldres->lr_name,
 		       sizeof(oldres->lr_name)) != 0);
-	lock->l_resource = newres;
+	rcu_assign_pointer(lock->l_resource, newres);
 	unlock_res(oldres);
-	unlock_res_and_lock(lock);
+	unlock_res(newres);
 
 	/* ...and the flowers are still standing! */
 	lu_ref_del(&oldres->lr_reference, "lock", lock);
@@ -1964,11 +1964,11 @@ void _ldlm_lock_debug(struct ldlm_lock *lock,
 	va_list args;
 	struct va_format vaf;
 
-	if (spin_trylock(&lock->l_lock)) {
-		if (lock->l_resource)
-			resource = ldlm_resource_getref(lock->l_resource);
-		spin_unlock(&lock->l_lock);
-	}
+	rcu_read_lock();
+	resource = rcu_dereference(lock->l_resource);
+	if (resource && !atomic_inc_not_zero(&resource->lr_refcount))
+		resource = NULL;
+	rcu_read_unlock();
 
 	va_start(args, fmt);
 	vaf.fmt = fmt;
diff --git a/fs/lustre/ldlm/ldlm_lockd.c b/fs/lustre/ldlm/ldlm_lockd.c
index 589b89d..ea87fd6 100644
--- a/fs/lustre/ldlm/ldlm_lockd.c
+++ b/fs/lustre/ldlm/ldlm_lockd.c
@@ -1097,6 +1097,23 @@ static int ldlm_cleanup(void)
 	return 0;
 }
 
+void ldlm_resource_init_once(void *p)
+{
+	/*
+	 * It is import to initialise the spinlock only once,
+	 * as ldlm_lock_change_resource() could try to lock
+	 * the resource *after* it has been freed and possibly
+	 * reused. SLAB_TYPESAFE_BY_RCU ensures the memory won't
+	 * be freed while the lock is being taken, but we need to
+	 * ensure that it doesn't get reinitialized either.
+	 */
+	struct ldlm_resource *res = p;
+
+	memset(res, 0, sizeof(*res));
+	mutex_init(&res->lr_lvb_mutex);
+	spin_lock_init(&res->lr_lock);
+}
+
 int ldlm_init(void)
 {
 	mutex_init(&ldlm_ref_mutex);
@@ -1104,7 +1121,9 @@ int ldlm_init(void)
 	mutex_init(ldlm_namespace_lock(LDLM_NAMESPACE_CLIENT));
 	ldlm_resource_slab = kmem_cache_create("ldlm_resources",
 					       sizeof(struct ldlm_resource), 0,
-					       SLAB_HWCACHE_ALIGN, NULL);
+					       SLAB_TYPESAFE_BY_RCU |
+					       SLAB_HWCACHE_ALIGN,
+					       ldlm_resource_init_once);
 	if (!ldlm_resource_slab)
 		return -ENOMEM;
 
diff --git a/fs/lustre/ldlm/ldlm_resource.c b/fs/lustre/ldlm/ldlm_resource.c
index 45b2e97..d79f70d 100644
--- a/fs/lustre/ldlm/ldlm_resource.c
+++ b/fs/lustre/ldlm/ldlm_resource.c
@@ -994,12 +994,14 @@ static struct ldlm_resource *ldlm_resource_new(enum ldlm_type ldlm_type)
 {
 	struct ldlm_resource *res;
 
-	res = kmem_cache_zalloc(ldlm_resource_slab, GFP_NOFS);
+	res = kmem_cache_alloc(ldlm_resource_slab, GFP_NOFS);
 	if (!res)
 		return NULL;
 
 	INIT_LIST_HEAD(&res->lr_granted);
 	INIT_LIST_HEAD(&res->lr_waiting);
+	res->lr_lvb_inode = NULL;
+	res->lr_lvb_len = 0;
 
 	if (ldlm_type == LDLM_EXTENT) {
 		int idx;
@@ -1017,16 +1019,15 @@ static struct ldlm_resource *ldlm_resource_new(enum ldlm_type ldlm_type)
 			res->lr_itree[idx].lit_mode = 1 << idx;
 			res->lr_itree[idx].lit_root = RB_ROOT_CACHED;
 		}
-	}
+	} else
+		res->lr_itree = NULL;
 
 	atomic_set(&res->lr_refcount, 1);
-	spin_lock_init(&res->lr_lock);
 	lu_ref_init(&res->lr_reference);
 
 	/* The creator of the resource must unlock the mutex after LVB
 	 * initialization.
 	 */
-	mutex_init(&res->lr_lvb_mutex);
 	mutex_lock(&res->lr_lvb_mutex);
 
 	return res;
