mm: memcontrol: rein in the CONFIG space madness

What CONFIG_INET and CONFIG_LEGACY_KMEM guard inside the memory
controller code is insignificant, having these conditionals is not
worth the complication and fragility that comes with them.

[akpm@linux-foundation.org: rework mem_cgroup_css_free() statement ordering]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

init/Kconfig

@@ -964,20 +964,6 @@ config MEMCG_SWAP_ENABLED
 	  For those who want to have the feature enabled by default should
 	  select this option (if, for some reason, they need to disable it
 	  then swapaccount=0 does the trick).
-config MEMCG_LEGACY_KMEM
-       bool
-config MEMCG_KMEM
-	bool "Legacy Memory Resource Controller Kernel Memory accounting"
-	depends on MEMCG
-	depends on SLUB || SLAB
-	select MEMCG_LEGACY_KMEM
-	help
-	  The Kernel Memory extension for Memory Resource Controller can limit
-	  the amount of memory used by kernel objects in the system. Those are
-	  fundamentally different from the entities handled by the standard
-	  Memory Controller, which are page-based, and can be swapped. Users of
-	  the kmem extension can use it to guarantee that no group of processes
-	  will ever exhaust kernel resources alone.
 
 config BLK_CGROUP
 	bool "IO controller"
@@ -1190,10 +1176,9 @@ config USER_NS
 	  to provide different user info for different servers.
 
 	  When user namespaces are enabled in the kernel it is
-	  recommended that the MEMCG and MEMCG_KMEM options also be
-	  enabled and that user-space use the memory control groups to
-	  limit the amount of memory a memory unprivileged users can
-	  use.
+	  recommended that the MEMCG option also be enabled and that
+	  user-space use the memory control groups to limit the amount
+	  of memory a memory unprivileged users can use.
 
 	  If unsure, say N.