kmemleak: Allow partial freeing of memory blocks
Functions like free_bootmem() are allowed to free only part of a memory
block. This patch adds support for this via the kmemleak_free_part()
callback which removes the original object and creates one or two
additional objects as a result of the memory block split.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 466d390..5aabd41 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -210,6 +210,7 @@
enum {
KMEMLEAK_ALLOC,
KMEMLEAK_FREE,
+ KMEMLEAK_FREE_PART,
KMEMLEAK_NOT_LEAK,
KMEMLEAK_IGNORE,
KMEMLEAK_SCAN_AREA,
@@ -523,27 +524,17 @@
* Remove the metadata (struct kmemleak_object) for a memory block from the
* object_list and object_tree_root and decrement its use_count.
*/
-static void delete_object(unsigned long ptr)
+static void __delete_object(struct kmemleak_object *object)
{
unsigned long flags;
- struct kmemleak_object *object;
write_lock_irqsave(&kmemleak_lock, flags);
- object = lookup_object(ptr, 0);
- if (!object) {
-#ifdef DEBUG
- kmemleak_warn("Freeing unknown object at 0x%08lx\n",
- ptr);
-#endif
- write_unlock_irqrestore(&kmemleak_lock, flags);
- return;
- }
prio_tree_remove(&object_tree_root, &object->tree_node);
list_del_rcu(&object->object_list);
write_unlock_irqrestore(&kmemleak_lock, flags);
WARN_ON(!(object->flags & OBJECT_ALLOCATED));
- WARN_ON(atomic_read(&object->use_count) < 1);
+ WARN_ON(atomic_read(&object->use_count) < 2);
/*
* Locking here also ensures that the corresponding memory block
@@ -556,6 +547,64 @@
}
/*
+ * Look up the metadata (struct kmemleak_object) corresponding to ptr and
+ * delete it.
+ */
+static void delete_object_full(unsigned long ptr)
+{
+ struct kmemleak_object *object;
+
+ object = find_and_get_object(ptr, 0);
+ if (!object) {
+#ifdef DEBUG
+ kmemleak_warn("Freeing unknown object at 0x%08lx\n",
+ ptr);
+#endif
+ return;
+ }
+ __delete_object(object);
+ put_object(object);
+}
+
+/*
+ * Look up the metadata (struct kmemleak_object) corresponding to ptr and
+ * delete it. If the memory block is partially freed, the function may create
+ * additional metadata for the remaining parts of the block.
+ */
+static void delete_object_part(unsigned long ptr, size_t size)
+{
+ struct kmemleak_object *object;
+ unsigned long start, end;
+
+ object = find_and_get_object(ptr, 1);
+ if (!object) {
+#ifdef DEBUG
+ kmemleak_warn("Partially freeing unknown object at 0x%08lx "
+ "(size %zu)\n", ptr, size);
+#endif
+ return;
+ }
+ __delete_object(object);
+
+ /*
+ * Create one or two objects that may result from the memory block
+ * split. Note that partial freeing is only done by free_bootmem() and
+ * this happens before kmemleak_init() is called. The path below is
+ * only executed during early log recording in kmemleak_init(), so
+ * GFP_KERNEL is enough.
+ */
+ start = object->pointer;
+ end = object->pointer + object->size;
+ if (ptr > start)
+ create_object(start, ptr - start, object->min_count,
+ GFP_KERNEL);
+ if (ptr + size < end)
+ create_object(ptr + size, end - ptr - size, object->min_count,
+ GFP_KERNEL);
+
+ put_object(object);
+}
+/*
* Make a object permanently as gray-colored so that it can no longer be
* reported as a leak. This is used in general to mark a false positive.
*/
@@ -719,13 +768,28 @@
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
- delete_object((unsigned long)ptr);
+ delete_object_full((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_FREE, ptr, 0, 0, 0, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_free);
/*
+ * Partial memory freeing function callback. This function is usually called
+ * from bootmem allocator when (part of) a memory block is freed.
+ */
+void kmemleak_free_part(const void *ptr, size_t size)
+{
+ pr_debug("%s(0x%p)\n", __func__, ptr);
+
+ if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
+ delete_object_part((unsigned long)ptr, size);
+ else if (atomic_read(&kmemleak_early_log))
+ log_early(KMEMLEAK_FREE_PART, ptr, size, 0, 0, 0);
+}
+EXPORT_SYMBOL_GPL(kmemleak_free_part);
+
+/*
* Mark an already allocated memory block as a false positive. This will cause
* the block to no longer be reported as leak and always be scanned.
*/
@@ -1318,7 +1382,7 @@
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list)
- delete_object(object->pointer);
+ delete_object_full(object->pointer);
rcu_read_unlock();
mutex_unlock(&scan_mutex);
@@ -1413,6 +1477,9 @@
case KMEMLEAK_FREE:
kmemleak_free(log->ptr);
break;
+ case KMEMLEAK_FREE_PART:
+ kmemleak_free_part(log->ptr, log->size);
+ break;
case KMEMLEAK_NOT_LEAK:
kmemleak_not_leak(log->ptr);
break;