mm: memcontrol: use "max" instead of "infinity" in control knobs

The memcg control knobs indicate the highest possible value using the
symbolic name "infinity", which is long and awkward to type.

Switch to the string "max", which is just as descriptive but shorter and
sweeter.

This changes a user interface, so do it before the release and before
the development flag is dropped from the default hierarchy.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/cgroups/unified-hierarchy.txt b/Documentation/cgroups/unified-hierarchy.txt
index 71daa35..eb102fb 100644
--- a/Documentation/cgroups/unified-hierarchy.txt
+++ b/Documentation/cgroups/unified-hierarchy.txt
@@ -404,8 +404,8 @@
   be understood as an underflow into the highest possible value, -2 or
   -10M etc. do not work, so it's not consistent.
 
-  memory.low, memory.high, and memory.max will use the string
-  "infinity" to indicate and set the highest possible value.
+  memory.low, memory.high, and memory.max will use the string "max" to
+  indicate and set the highest possible value.
 
 5. Planned Changes