diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt
index 2ec6adb..c4171e4 100644
--- a/Documentation/vm/transhuge.txt
+++ b/Documentation/vm/transhuge.txt
@@ -136,6 +136,11 @@
 echo 0 >/sys/kernel/mm/transparent_hugepage/use_zero_page
 echo 1 >/sys/kernel/mm/transparent_hugepage/use_zero_page
 
+Some userspace (such as a test program, or an optimized memory allocation
+library) may want to know the size (in bytes) of a transparent hugepage:
+
+cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size
+
 khugepaged will be automatically started when
 transparent_hugepage/enabled is set to "always" or "madvise, and it'll
 be automatically shutdown if it's set to "never".
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2b44ac1..cee42cf 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -285,6 +285,15 @@ static ssize_t use_zero_page_store(struct kobject *kobj,
 }
 static struct kobj_attribute use_zero_page_attr =
 	__ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
+
+static ssize_t hpage_pmd_size_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
+}
+static struct kobj_attribute hpage_pmd_size_attr =
+	__ATTR_RO(hpage_pmd_size);
+
 #ifdef CONFIG_DEBUG_VM
 static ssize_t debug_cow_show(struct kobject *kobj,
 				struct kobj_attribute *attr, char *buf)
@@ -307,6 +316,7 @@ static struct attribute *hugepage_attr[] = {
 	&enabled_attr.attr,
 	&defrag_attr.attr,
 	&use_zero_page_attr.attr,
+	&hpage_pmd_size_attr.attr,
 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
 	&shmem_enabled_attr.attr,
 #endif