Merge branch 'akpm' (patches from Andrew)

Merge more fixes from Andrew Morton: "Three fixes" * emailed patches from Andrew Morton <[email protected]>: include/linux/property.h: fix typo/compile error ocfs2: fix deadlock on mmapped page in ocfs2_write_begin_nolock() mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()
josf · Sep 30, 2016 · dbd8805 · dbd8805
2 parents 9a2172a + 37aa727
commit dbd8805
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Showing 5 changed files with 74 additions and 64 deletions.
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
@@ -1842,6 +1842,16 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
 	ocfs2_commit_trans(osb, handle);
 
 out:
+	/*
+	 * The mmapped page won't be unlocked in ocfs2_free_write_ctxt(),
+	 * even in case of error here like ENOSPC and ENOMEM. So, we need
+	 * to unlock the target page manually to prevent deadlocks when
+	 * retrying again on ENOSPC, or when returning non-VM_FAULT_LOCKED
+	 * to VM code.
+	 */
+	if (wc->w_target_locked)
+		unlock_page(mmap_page);
+
 	ocfs2_free_write_ctxt(inode, wc);
 
 	if (data_ac) {

diff --git a/include/linux/property.h b/include/linux/property.h
@@ -190,7 +190,7 @@ struct property_entry {
 	.length = ARRAY_SIZE(_val_) * sizeof(_type_),		\
 	.is_array = true,					\
 	.is_string = false,					\
-	{ .pointer = { _type_##_data = _val_ } },		\
+	{ .pointer = { ._type_##_data = _val_ } },		\
 }
 
 #define PROPERTY_ENTRY_U8_ARRAY(_name_, _val_)			\

diff --git a/include/linux/swap.h b/include/linux/swap.h
@@ -257,6 +257,7 @@ static inline void workingset_node_pages_inc(struct radix_tree_node *node)
 
 static inline void workingset_node_pages_dec(struct radix_tree_node *node)
 {
+	VM_BUG_ON(!workingset_node_pages(node));
 	node->count--;
 }
 
@@ -272,6 +273,7 @@ static inline void workingset_node_shadows_inc(struct radix_tree_node *node)
 
 static inline void workingset_node_shadows_dec(struct radix_tree_node *node)
 {
+	VM_BUG_ON(!workingset_node_shadows(node));
 	node->count -= 1U << RADIX_TREE_COUNT_SHIFT;
 }
 

diff --git a/mm/filemap.c b/mm/filemap.c
@@ -110,6 +110,62 @@
  *   ->tasklist_lock            (memory_failure, collect_procs_ao)
  */
 
+static int page_cache_tree_insert(struct address_space *mapping,
+				  struct page *page, void **shadowp)
+{
+	struct radix_tree_node *node;
+	void **slot;
+	int error;
+
+	error = __radix_tree_create(&mapping->page_tree, page->index, 0,
+				    &node, &slot);
+	if (error)
+		return error;
+	if (*slot) {
+		void *p;
+
+		p = radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
+		if (!radix_tree_exceptional_entry(p))
+			return -EEXIST;
+
+		mapping->nrexceptional--;
+		if (!dax_mapping(mapping)) {
+			if (shadowp)
+				*shadowp = p;
+			if (node)
+				workingset_node_shadows_dec(node);
+		} else {
+			/* DAX can replace empty locked entry with a hole */
+			WARN_ON_ONCE(p !=
+				(void *)(RADIX_TREE_EXCEPTIONAL_ENTRY |
+					 RADIX_DAX_ENTRY_LOCK));
+			/* DAX accounts exceptional entries as normal pages */
+			if (node)
+				workingset_node_pages_dec(node);
+			/* Wakeup waiters for exceptional entry lock */
+			dax_wake_mapping_entry_waiter(mapping, page->index,
+						      false);
+		}
+	}
+	radix_tree_replace_slot(slot, page);
+	mapping->nrpages++;
+	if (node) {
+		workingset_node_pages_inc(node);
+		/*
+		 * Don't track node that contains actual pages.
+		 *
+		 * Avoid acquiring the list_lru lock if already
+		 * untracked.  The list_empty() test is safe as
+		 * node->private_list is protected by
+		 * mapping->tree_lock.
+		 */
+		if (!list_empty(&node->private_list))
+			list_lru_del(&workingset_shadow_nodes,
+				     &node->private_list);
+	}
+	return 0;
+}
+
 static void page_cache_tree_delete(struct address_space *mapping,
 				   struct page *page, void *shadow)
 {
@@ -561,7 +617,7 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
 
 		spin_lock_irqsave(&mapping->tree_lock, flags);
 		__delete_from_page_cache(old, NULL);
-		error = radix_tree_insert(&mapping->page_tree, offset, new);
+		error = page_cache_tree_insert(mapping, new, NULL);
 		BUG_ON(error);
 		mapping->nrpages++;
 
@@ -584,62 +640,6 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
 }
 EXPORT_SYMBOL_GPL(replace_page_cache_page);
 
-static int page_cache_tree_insert(struct address_space *mapping,
-				  struct page *page, void **shadowp)
-{
-	struct radix_tree_node *node;
-	void **slot;
-	int error;
-
-	error = __radix_tree_create(&mapping->page_tree, page->index, 0,
-				    &node, &slot);
-	if (error)
-		return error;
-	if (*slot) {
-		void *p;
-
-		p = radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
-		if (!radix_tree_exceptional_entry(p))
-			return -EEXIST;
-
-		mapping->nrexceptional--;
-		if (!dax_mapping(mapping)) {
-			if (shadowp)
-				*shadowp = p;
-			if (node)
-				workingset_node_shadows_dec(node);
-		} else {
-			/* DAX can replace empty locked entry with a hole */
-			WARN_ON_ONCE(p !=
-				(void *)(RADIX_TREE_EXCEPTIONAL_ENTRY |
-					 RADIX_DAX_ENTRY_LOCK));
-			/* DAX accounts exceptional entries as normal pages */
-			if (node)
-				workingset_node_pages_dec(node);
-			/* Wakeup waiters for exceptional entry lock */
-			dax_wake_mapping_entry_waiter(mapping, page->index,
-						      false);
-		}
-	}
-	radix_tree_replace_slot(slot, page);
-	mapping->nrpages++;
-	if (node) {
-		workingset_node_pages_inc(node);
-		/*
-		 * Don't track node that contains actual pages.
-		 *
-		 * Avoid acquiring the list_lru lock if already
-		 * untracked.  The list_empty() test is safe as
-		 * node->private_list is protected by
-		 * mapping->tree_lock.
-		 */
-		if (!list_empty(&node->private_list))
-			list_lru_del(&workingset_shadow_nodes,
-				     &node->private_list);
-	}
-	return 0;
-}
-
 static int __add_to_page_cache_locked(struct page *page,
 				      struct address_space *mapping,
 				      pgoff_t offset, gfp_t gfp_mask,

diff --git a/mm/workingset.c b/mm/workingset.c
@@ -418,21 +418,19 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 	 * no pages, so we expect to be able to remove them all and
 	 * delete and free the empty node afterwards.
 	 */
-
-	BUG_ON(!node->count);
-	BUG_ON(node->count & RADIX_TREE_COUNT_MASK);
+	BUG_ON(!workingset_node_shadows(node));
+	BUG_ON(workingset_node_pages(node));
 
 	for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
 		if (node->slots[i]) {
 			BUG_ON(!radix_tree_exceptional_entry(node->slots[i]));
 			node->slots[i] = NULL;
-			BUG_ON(node->count < (1U << RADIX_TREE_COUNT_SHIFT));
-			node->count -= 1U << RADIX_TREE_COUNT_SHIFT;
+			workingset_node_shadows_dec(node);
 			BUG_ON(!mapping->nrexceptional);
 			mapping->nrexceptional--;
 		}
 	}
-	BUG_ON(node->count);
+	BUG_ON(workingset_node_shadows(node));
 	inc_node_state(page_pgdat(virt_to_page(node)), WORKINGSET_NODERECLAIM);
 	if (!__radix_tree_delete_node(&mapping->page_tree, node))
 		BUG();