mm/rmap: Convert the struct anon_vma::mutex to an rwsem

[karo-tx-linux.git] / mm / rmap.c

diff --git a/mm/rmap.c b/mm/rmap.c
index 2ee1ef0f317b7487bfb21b7a6717b1e12d1f7ef4..6e3ee3b82798f3fa59a1daa18321ba86a15afb97 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -24,7 +24,7 @@
  *   mm->mmap_sem
  *     page->flags PG_locked (lock_page)
  *       mapping->i_mmap_mutex
- *         anon_vma->mutex
+ *         anon_vma->rwsem
  *           mm->page_table_lock or pte_lock
  *             zone->lru_lock (in mark_page_accessed, isolate_lru_page)
  *             swap_lock (in swap_duplicate, swap_info_get)
@@ -37,7 +37,7 @@
  *                           in arch-dependent flush_dcache_mmap_lock,
  *                           within bdi.wb->list_lock in __sync_single_inode)
  *
- * anon_vma->mutex,mapping->i_mutex      (memory_failure, collect_procs_anon)
+ * anon_vma->rwsem,mapping->i_mutex      (memory_failure, collect_procs_anon)
  *   ->tasklist_lock
  *     pte map lock
  */
@@ -103,7 +103,7 @@ static inline void anon_vma_free(struct anon_vma *anon_vma)
         * LOCK should suffice since the actual taking of the lock must
         * happen _before_ what follows.
         */
-       if (mutex_is_locked(&anon_vma->root->mutex)) {
+       if (rwsem_is_locked(&anon_vma->root->rwsem)) {
                anon_vma_lock(anon_vma);
                anon_vma_unlock(anon_vma);
        }
@@ -219,9 +219,9 @@ static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct
        struct anon_vma *new_root = anon_vma->root;
        if (new_root != root) {
                if (WARN_ON_ONCE(root))
-                       mutex_unlock(&root->mutex);
+                       up_write(&root->rwsem);
                root = new_root;
-               mutex_lock(&root->mutex);
+               down_write(&root->rwsem);
        }
        return root;
 }
@@ -229,7 +229,7 @@ static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct
 static inline void unlock_anon_vma_root(struct anon_vma *root)
 {
        if (root)
-               mutex_unlock(&root->mutex);
+               up_write(&root->rwsem);
 }
 
 /*
@@ -349,7 +349,7 @@ void unlink_anon_vmas(struct vm_area_struct *vma)
        /*
         * Iterate the list once more, it now only contains empty and unlinked
         * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
-        * needing to acquire the anon_vma->root->mutex.
+        * needing to write-acquire the anon_vma->root->rwsem.
         */
        list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
                struct anon_vma *anon_vma = avc->anon_vma;
@@ -365,7 +365,7 @@ static void anon_vma_ctor(void *data)
 {
        struct anon_vma *anon_vma = data;
 
-       mutex_init(&anon_vma->mutex);
+       init_rwsem(&anon_vma->rwsem);
        atomic_set(&anon_vma->refcount, 0);
        anon_vma->rb_root = RB_ROOT;
 }
@@ -457,14 +457,14 @@ struct anon_vma *page_lock_anon_vma(struct page *page)
 
        anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
        root_anon_vma = ACCESS_ONCE(anon_vma->root);
-       if (mutex_trylock(&root_anon_vma->mutex)) {
+       if (down_write_trylock(&root_anon_vma->rwsem)) {
                /*
                 * If the page is still mapped, then this anon_vma is still
                 * its anon_vma, and holding the mutex ensures that it will
                 * not go away, see anon_vma_free().
                 */
                if (!page_mapped(page)) {
-                       mutex_unlock(&root_anon_vma->mutex);
+                       up_write(&root_anon_vma->rwsem);
                        anon_vma = NULL;
                }
                goto out;
@@ -1299,7 +1299,7 @@ out_mlock:
        /*
         * We need mmap_sem locking, Otherwise VM_LOCKED check makes
         * unstable result and race. Plus, We can't wait here because
-        * we now hold anon_vma->mutex or mapping->i_mmap_mutex.
+        * we now hold anon_vma->rwsem or mapping->i_mmap_mutex.
         * if trylock failed, the page remain in evictable lru and later
         * vmscan could retry to move the page to unevictable lru if the
         * page is actually mlocked.