Documentation: sysfs/memory: clarify some memory block device properties

In commit 53cdc1cb29e8 ("drivers/base/memory.c: indicate all memory blocks
as removable") we changed the output of the "removable" property of memory
devices to return "1" if and only if the kernel supports memory offlining.

Let's update documentation, stating that the interface is legacy.  Also
update documentation of the "state" property and "valid_zones" properties.

Link: https://lkml.kernel.org/r/20210201181347.13262-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 8 deletions

diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst
index 245739f55ac7..5307f90738aa 100644
--- a/Documentation/admin-guide/mm/memory-hotplug.rst
+++ b/Documentation/admin-guide/mm/memory-hotplug.rst
@@ -162,14 +162,14 @@ Under each memory block, you can see 5 files:
                     which will be performed on all sections in the block.
 ``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
-                    block is removable and a value of 0 indicates that
-                    it is not removable. A memory block is removable only if
-                    every section in the block is removable.
-``valid_zones``     read-only: designed to show which zones this memory block
-		    can be onlined to.
+``removable``	    read-only: legacy interface that indicated whether a memory
+		    block was likely to be offlineable or not.  Newer kernel
+		    versions return "1" if and only if the kernel supports
+		    memory offlining.
+``valid_zones``     read-only: designed to show by which zone memory provided by
+		    a memory block is managed, and to show by which zone memory
+		    provided by an offline memory block could be managed when
+		    onlining.
 
 		    The first column shows it`s default zone.