diff --git a/Documentation/ABI/testing/sysfs-devices-memory b/Documentation/ABI/testing/sysfs-devices-memory
index 2da2b1fba2c1..16a727a611b1 100644
--- a/Documentation/ABI/testing/sysfs-devices-memory
+++ b/Documentation/ABI/testing/sysfs-devices-memory
@@ -26,8 +26,9 @@ Date:		September 2008
 Contact:	Badari Pulavarty <pbadari@us.ibm.com>
 Description:
 		The file /sys/devices/system/memory/memoryX/phys_device
-		is read-only and is designed to show the name of physical
-		memory device.  Implementation is currently incomplete.
+		is read-only;  it is a legacy interface only ever used on s390x
+		to expose the covered storage increment.
+Users:		Legacy s390-tools lsmem/chmem
 
 What:		/sys/devices/system/memory/memoryX/phys_index
 Date:		September 2008
diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst
index 5c4432c96c4b..245739f55ac7 100644
--- a/Documentation/admin-guide/mm/memory-hotplug.rst
+++ b/Documentation/admin-guide/mm/memory-hotplug.rst
@@ -160,8 +160,8 @@ Under each memory block, you can see 5 files:
 
                     "online_movable", "online", "offline" command
                     which will be performed on all sections in the block.
-``phys_device``     read-only: designed to show the name of physical memory
-                    device.  This is not well implemented now.
+``phys_device``	    read-only: legacy interface only ever used on s390x to
+		    expose the covered storage increment.
 ``removable``       read-only: contains an integer value indicating
                     whether the memory block is removable or not
                     removable.  A value of 1 indicates that the memory
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index eef4ffb6122c..de058d15b33e 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -290,20 +290,20 @@ static ssize_t state_store(struct device *dev, struct device_attribute *attr,
 }
 
 /*
- * phys_device is a bad name for this.  What I really want
- * is a way to differentiate between memory ranges that
- * are part of physical devices that constitute
- * a complete removable unit or fru.
- * i.e. do these ranges belong to the same physical device,
- * s.t. if I offline all of these sections I can then
- * remove the physical device?
+ * Legacy interface that we cannot remove: s390x exposes the storage increment
+ * covered by a memory block, allowing for identifying which memory blocks
+ * comprise a storage increment. Since a memory block spans complete
+ * storage increments nowadays, this interface is basically unused. Other
+ * archs never exposed != 0.
  */
 static ssize_t phys_device_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	struct memory_block *mem = to_memory_block(dev);
+	unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
 
-	return sysfs_emit(buf, "%d\n", mem->phys_device);
+	return sysfs_emit(buf, "%d\n",
+			  arch_get_memory_phys_device(start_pfn));
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
@@ -488,11 +488,7 @@ static DEVICE_ATTR_WO(soft_offline_page);
 static DEVICE_ATTR_WO(hard_offline_page);
 #endif
 
-/*
- * Note that phys_device is optional.  It is here to allow for
- * differentiation between which *physical* devices each
- * section belongs to...
- */
+/* See phys_device_show(). */
 int __weak arch_get_memory_phys_device(unsigned long start_pfn)
 {
 	return 0;
@@ -574,7 +570,6 @@ int register_memory(struct memory_block *memory)
 static int init_memory_block(unsigned long block_id, unsigned long state)
 {
 	struct memory_block *mem;
-	unsigned long start_pfn;
 	int ret = 0;
 
 	mem = find_memory_block_by_id(block_id);
@@ -588,8 +583,6 @@ static int init_memory_block(unsigned long block_id, unsigned long state)
 
 	mem->start_section_nr = block_id * sections_per_block;
 	mem->state = state;
-	start_pfn = section_nr_to_pfn(mem->start_section_nr);
-	mem->phys_device = arch_get_memory_phys_device(start_pfn);
 	mem->nid = NUMA_NO_NODE;
 
 	ret = register_memory(mem);
diff --git a/include/linux/memory.h b/include/linux/memory.h
index 439a89e758d8..4da95e684e20 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -27,9 +27,8 @@ struct memory_block {
 	unsigned long start_section_nr;
 	unsigned long state;		/* serialized by the dev->lock */
 	int online_type;		/* for passing data to online routine */
-	int phys_device;		/* to which fru does this belong? */
-	struct device dev;
 	int nid;			/* NID for this memory block */
+	struct device dev;
 };
 
 int arch_get_memory_phys_device(unsigned long start_pfn);