[PATCH] memcg: mark CONFIG_MEMCG broken for !CONFIG_MMU

[Michal Hocko]

CONFIG_MEMCG might be currently enabled also for !MMU architectures
which was probably an omission because Balbir had this on the TODO
list section (https://lkml.org/lkml/2008/3/16/59)
"
Only when CONFIG_MMU is enabled, is the virtual address space control
enabled. Should we do this for nommu cases as well? My suspicion is
that we don't have to.
"
I do not see any traces for !MMU requests after then. The code compiles
with !MMU but I haven't heard about anybody using it in the real life
so it is not clear to me whether it works and it is usable at all. At
least anonymous mmaps do not try to charge the memory and who knows what
else is broken.

Let's make CONFIG_MEMCG depend on BROKEN for !CONFIG_MMU to make the
current status explicit for somebody who might be interested in using
MEMCG and report it to us so that we can help with fixing it up.

Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
---
 init/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/init/Kconfig b/init/Kconfig
index 9afb971497f4..f5373c4188c0 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -979,6 +979,7 @@ config MEMCG
 	bool "Memory Resource Controller for Control Groups"
 	select PAGE_COUNTER
 	select EVENTFD
+	depends on MMU || BROKEN
 	help
 	  Provides a memory resource controller that manages both anonymous
 	  memory and page cache. (See Documentation/cgroups/memory.txt)
-- 
2.1.4

-- 
Michal Hocko
SUSE Labs
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