XArray/IDA updates for 6.6

- Fix a bug encountered by people using bittorrent where they'd get
    NULL pointer dereferences on page cache lookups when using XFS
 
  - Two documentation fixes
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Merge tag 'xarray-6.6' of git://git.infradead.org/users/willy/xarray

Pull xarray fixes from Matthew Wilcox:

 - Fix a bug encountered by people using bittorrent where they'd get
   NULL pointer dereferences on page cache lookups when using XFS

 - Two documentation fixes

* tag 'xarray-6.6' of git://git.infradead.org/users/willy/xarray:
  idr: fix param name in idr_alloc_cyclic() doc
  xarray: Document necessary flag in alloc functions
  XArray: Do not return sibling entries from xa_load()

include/linux/xarray.h

@@ -856,6 +856,9 @@ static inline int __must_check xa_insert_irq(struct xarray *xa,
  * stores the index into the @id pointer, then stores the entry at
  * that index.  A concurrent lookup will not see an uninitialised @id.
  *
+ * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
+ * in xa_init_flags().
+ *
  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
  * the @gfp flags permit.
  * Return: 0 on success, -ENOMEM if memory could not be allocated or
@@ -886,6 +889,9 @@ static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
  * stores the index into the @id pointer, then stores the entry at
  * that index.  A concurrent lookup will not see an uninitialised @id.
  *
+ * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
+ * in xa_init_flags().
+ *
  * Context: Any context.  Takes and releases the xa_lock while
  * disabling softirqs.  May sleep if the @gfp flags permit.
  * Return: 0 on success, -ENOMEM if memory could not be allocated or
@@ -916,6 +922,9 @@ static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
  * stores the index into the @id pointer, then stores the entry at
  * that index.  A concurrent lookup will not see an uninitialised @id.
  *
+ * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
+ * in xa_init_flags().
+ *
  * Context: Process context.  Takes and releases the xa_lock while
  * disabling interrupts.  May sleep if the @gfp flags permit.
  * Return: 0 on success, -ENOMEM if memory could not be allocated or
@@ -949,6 +958,9 @@ static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
  * The search for an empty entry will start at @next and will wrap
  * around if necessary.
  *
+ * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
+ * in xa_init_flags().
+ *
  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
  * the @gfp flags permit.
  * Return: 0 if the allocation succeeded without wrapping.  1 if the
@@ -983,6 +995,9 @@ static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
  * The search for an empty entry will start at @next and will wrap
  * around if necessary.
  *
+ * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
+ * in xa_init_flags().
+ *
  * Context: Any context.  Takes and releases the xa_lock while
  * disabling softirqs.  May sleep if the @gfp flags permit.
  * Return: 0 if the allocation succeeded without wrapping.  1 if the
@@ -1017,6 +1032,9 @@ static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry,
  * The search for an empty entry will start at @next and will wrap
  * around if necessary.
  *
+ * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
+ * in xa_init_flags().
+ *
  * Context: Process context.  Takes and releases the xa_lock while
  * disabling interrupts.  May sleep if the @gfp flags permit.
  * Return: 0 if the allocation succeeded without wrapping.  1 if the

lib/idr.c

@@ -100,7 +100,7 @@ EXPORT_SYMBOL_GPL(idr_alloc);
  * @end: The maximum ID (exclusive).
  * @gfp: Memory allocation flags.
  *
- * Allocates an unused ID in the range specified by @nextid and @end.  If
+ * Allocates an unused ID in the range specified by @start and @end.  If
  * @end is <= 0, it is treated as one larger than %INT_MAX.  This allows
  * callers to use @start + N as @end as long as N is within integer range.
  * The search for an unused ID will start at the last ID allocated and will

lib/xarray.c

@@ -206,7 +206,7 @@ static void *xas_descend(struct xa_state *xas, struct xa_node *node)
 	void *entry = xa_entry(xas->xa, node, offset);
 
 	xas->xa_node = node;
-	if (xa_is_sibling(entry)) {
+	while (xa_is_sibling(entry)) {
 		offset = xa_to_sibling(entry);
 		entry = xa_entry(xas->xa, node, offset);
 		if (node->shift && xa_is_node(entry))
@@ -1802,6 +1802,9 @@ EXPORT_SYMBOL(xa_get_order);
  * stores the index into the @id pointer, then stores the entry at
  * that index.  A concurrent lookup will not see an uninitialised @id.
  *
+ * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
+ * in xa_init_flags().
+ *
  * Context: Any context.  Expects xa_lock to be held on entry.  May
  * release and reacquire xa_lock if @gfp flags permit.
  * Return: 0 on success, -ENOMEM if memory could not be allocated or
@@ -1850,6 +1853,9 @@ EXPORT_SYMBOL(__xa_alloc);
  * The search for an empty entry will start at @next and will wrap
  * around if necessary.
  *
+ * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
+ * in xa_init_flags().
+ *
  * Context: Any context.  Expects xa_lock to be held on entry.  May
  * release and reacquire xa_lock if @gfp flags permit.
  * Return: 0 if the allocation succeeded without wrapping.  1 if the

tools/testing/radix-tree/multiorder.c

@@ -159,7 +159,7 @@ void multiorder_tagged_iteration(struct xarray *xa)
 	item_kill_tree(xa);
 }
 
-bool stop_iteration = false;
+bool stop_iteration;
 
 static void *creator_func(void *ptr)
 {
@@ -201,6 +201,7 @@ static void multiorder_iteration_race(struct xarray *xa)
 	pthread_t worker_thread[num_threads];
 	int i;
 
+	stop_iteration = false;
 	pthread_create(&worker_thread[0], NULL, &creator_func, xa);
 	for (i = 1; i < num_threads; i++)
 		pthread_create(&worker_thread[i], NULL, &iterator_func, xa);
@@ -211,6 +212,61 @@ static void multiorder_iteration_race(struct xarray *xa)
 	item_kill_tree(xa);
 }
 
+static void *load_creator(void *ptr)
+{
+	/* 'order' is set up to ensure we have sibling entries */
+	unsigned int order;
+	struct radix_tree_root *tree = ptr;
+	int i;
+
+	rcu_register_thread();
+	item_insert_order(tree, 3 << RADIX_TREE_MAP_SHIFT, 0);
+	item_insert_order(tree, 2 << RADIX_TREE_MAP_SHIFT, 0);
+	for (i = 0; i < 10000; i++) {
+		for (order = 1; order < RADIX_TREE_MAP_SHIFT; order++) {
+			unsigned long index = (3 << RADIX_TREE_MAP_SHIFT) -
+						(1 << order);
+			item_insert_order(tree, index, order);
+			item_delete_rcu(tree, index);
+		}
+	}
+	rcu_unregister_thread();
+
+	stop_iteration = true;
+	return NULL;
+}
+
+static void *load_worker(void *ptr)
+{
+	unsigned long index = (3 << RADIX_TREE_MAP_SHIFT) - 1;
+
+	rcu_register_thread();
+	while (!stop_iteration) {
+		struct item *item = xa_load(ptr, index);
+		assert(!xa_is_internal(item));
+	}
+	rcu_unregister_thread();
+
+	return NULL;
+}
+
+static void load_race(struct xarray *xa)
+{
+	const int num_threads = sysconf(_SC_NPROCESSORS_ONLN) * 4;
+	pthread_t worker_thread[num_threads];
+	int i;
+
+	stop_iteration = false;
+	pthread_create(&worker_thread[0], NULL, &load_creator, xa);
+	for (i = 1; i < num_threads; i++)
+		pthread_create(&worker_thread[i], NULL, &load_worker, xa);
+
+	for (i = 0; i < num_threads; i++)
+		pthread_join(worker_thread[i], NULL);
+
+	item_kill_tree(xa);
+}
+
 static DEFINE_XARRAY(array);
 
 void multiorder_checks(void)
@@ -218,12 +274,20 @@ void multiorder_checks(void)
 	multiorder_iteration(&array);
 	multiorder_tagged_iteration(&array);
 	multiorder_iteration_race(&array);
+	load_race(&array);
 
 	radix_tree_cpu_dead(0);
 }
 
-int __weak main(void)
+int __weak main(int argc, char **argv)
 {
+	int opt;
+
+	while ((opt = getopt(argc, argv, "ls:v")) != -1) {
+		if (opt == 'v')
+			test_verbose++;
+	}
+
 	rcu_register_thread();
 	radix_tree_init();
 	multiorder_checks();