[PATCH] mm: clarify COMPACTION Kconfig text

[Michal Hocko]

The current wording of the COMPACTION Kconfig help text doesn't
emphasise that disabling COMPACTION might cripple the page allocator
which relies on the compaction quite heavily for high order requests and
an unexpected OOM can happen with the lack of compaction. Make sure
we are vocal about that.

Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
---
 mm/Kconfig | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index 78a23c5c302d..be0ee11fa0d9 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -262,7 +262,14 @@ config COMPACTION
 	select MIGRATION
 	depends on MMU
 	help
-	  Allows the compaction of memory for the allocation of huge pages.
+          Compaction is the only memory management component to form
+          high order (larger physically contiguous) memory blocks
+          reliably. The page allocator relies on compaction heavily and
+          the lack of the feature can lead to unexpected OOM killer
+          invocations for high order memory requests. You shouldn't
+          disable this option unless there really is a strong reason for
+          it and then we would be really interested to hear about that at
+          linux-mm@xxxxxxxxxx
 
 #
 # support for page migration
-- 
2.8.1

-- 
Michal Hocko
SUSE Labs