Subject: mm_take_all_locks-rwsem

From: Andrea Arcangeli <andrea@qumranet.com>

Converts mm_take_all_locks to use semaphores after i_mmap_lock and
anon_vma_lock conversions.

Signed-off-by: Andrea Arcangeli <andrea@qumranet.com>
---

diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -134,7 +134,7 @@ struct mmu_notifier_ops {
  * Therefore notifier chains can only be traversed when either
  *
  * 1. mmap_sem is held.
- * 2. One of the reverse map locks is held (i_mmap_lock or anon_vma->lock).
+ * 2. One of the reverse map locks is held (i_mmap_sem or anon_vma->sem).
  * 3. No other concurrent thread can access the list (release)
  */
 struct mmu_notifier {
diff --git a/mm/mmap.c b/mm/mmap.c
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2266,15 +2266,15 @@ static void vm_lock_anon_vma(struct anon
 		 * The LSB of head.next can't change from under us
 		 * because we hold the mm_all_locks_mutex.
 		 */
-		spin_lock(&anon_vma->lock);
+		down_write(&anon_vma->sem);
 		/*
 		 * We can safely modify head.next after taking the
-		 * anon_vma->lock. If some other vma in this mm shares
+		 * anon_vma->sem. If some other vma in this mm shares
 		 * the same anon_vma we won't take it again.
 		 *
 		 * No need of atomic instructions here, head.next
 		 * can't change from under us thanks to the
-		 * anon_vma->lock.
+		 * anon_vma->sem.
 		 */
 		if (__test_and_set_bit(0, (unsigned long *)
 				       &anon_vma->head.next))
@@ -2296,7 +2296,7 @@ static void vm_lock_mapping(struct addre
 		 */
 		if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
 			BUG();
-		spin_lock(&mapping->i_mmap_lock);
+		down_write(&mapping->i_mmap_sem);
 	}
 }
 
@@ -2323,7 +2323,7 @@ static void vm_lock_mapping(struct addre
  * vma in this mm is backed by the same anon_vma or address_space.
  *
  * We can take all the locks in random order because the VM code
- * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
+ * taking i_mmap_sem or anon_vma->sem outside the mmap_sem never
  * takes more than one of them in a row. Secondly we're protected
  * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
  *
@@ -2371,12 +2371,12 @@ static void vm_unlock_anon_vma(struct an
 		 *
 		 * No need of atomic instructions here, head.next
 		 * can't change from under us until we release the
-		 * anon_vma->lock.
+		 * anon_vma->sem.
 		 */
 		if (!__test_and_clear_bit(0, (unsigned long *)
 					  &anon_vma->head.next))
 			BUG();
-		spin_unlock(&anon_vma->lock);
+		up_write(&anon_vma->sem);
 	}
 }
 
@@ -2387,7 +2387,7 @@ static void vm_unlock_mapping(struct add
 		 * AS_MM_ALL_LOCKS can't change to 0 from under us
 		 * because we hold the mm_all_locks_mutex.
 		 */
-		spin_unlock(&mapping->i_mmap_lock);
+		up_write(&mapping->i_mmap_sem);
 		if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
 					&mapping->flags))
 			BUG();