[PATCH] docs: ABI: update permission descriptions for slab page order

[<yang.yang29@zte.com.cn>]

From: Fan Yu <fan.yu9@zte.com.cn>

The page allocation order is now read-only, and cannot be 
changed by /sys/kernel/slab/<cache>/order file at run time,
see the following commit:

32a6f409b693 ("mm, slub: remove runtime allocation order changes")

But the ABI documetation have not been modified along with the code,
so they need to be updated, which will help readers better understand
the code.

Signed-off-by: Fan Yu <fan.yu9@zte.com.cn>
---
 Documentation/ABI/testing/sysfs-kernel-slab | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-kernel-slab b/Documentation/ABI/testing/sysfs-kernel-slab
index cd5fb8fa3ddf..8f0fc1cb3dc0 100644
--- a/Documentation/ABI/testing/sysfs-kernel-slab
+++ b/Documentation/ABI/testing/sysfs-kernel-slab
@@ -342,15 +342,14 @@ Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 		Christoph Lameter <cl@linux-foundation.org>
 Description:
 		The order file specifies the page order at which new slabs are
-		allocated.  It is writable and can be changed to increase the
-		number of objects per slab.  If a slab cannot be allocated
-		because of fragmentation, SLUB will retry with the minimum order
-		possible depending on its characteristics.
+		allocated. It is read-only and cannot be changed at run time.
+		If a slab cannot be allocated because of fragmentation, SLUB
+		will retry with the minimum order possible depending on
+		its characteristics.

 		When debug_guardpage_minorder=N (N > 0) parameter is specified
 		(see Documentation/admin-guide/kernel-parameters.rst), the minimum possible
-		order is used and this sysfs entry can not be used to change
-		the order at run time.
+		order is used.

 What:		/sys/kernel/slab/<cache>/order_fallback
 Date:		April 2008
-- 
2.25.1