1 files changed, 26 insertions, 0 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 58251ba63e4a..b7c6a40e436a 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1597,6 +1597,32 @@ void kzfree(const void *p)
 }
 EXPORT_SYMBOL(kzfree);
 
+/**
+ * ksize - get the actual amount of memory allocated for a given object
+ * @objp: Pointer to the object
+ *
+ * kmalloc may internally round up allocations and return more memory
+ * than requested. ksize() can be used to determine the actual amount of
+ * memory allocated. The caller may use this additional memory, even though
+ * a smaller amount of memory was initially specified with the kmalloc call.
+ * The caller must guarantee that objp points to a valid object previously
+ * allocated with either kmalloc() or kmem_cache_alloc(). The object
+ * must not be freed during the duration of the call.
+ *
+ * Return: size of the actual memory used by @objp in bytes
+ */
+size_t ksize(const void *objp)
+{
+	size_t size = __ksize(objp);
+	/*
+	 * We assume that ksize callers could use whole allocated area,
+	 * so we need to unpoison this area.
+	 */
+	kasan_unpoison_shadow(objp, size);
+	return size;
+}
+EXPORT_SYMBOL(ksize);
+
 /* Tracepoints definitions. */
 EXPORT_TRACEPOINT_SYMBOL(kmalloc);
 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);