The patch titled
Subject: mm: clarify COMPACTION Kconfig text
has been added to the -mm tree. Its filename is
mm-clarify-compaction-kconfig-text.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-clarify-compaction-kconfig-text.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-clarify-compaction-kconfig-text.patch
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------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxx>
Subject: mm: clarify COMPACTION Kconfig text
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.
Link: http://lkml.kernel.org/r/20160823091726.GK23577@xxxxxxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Joonsoo Kim <js1304@xxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/Kconfig | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff -puN mm/Kconfig~mm-clarify-compaction-kconfig-text mm/Kconfig
--- a/mm/Kconfig~mm-clarify-compaction-kconfig-text
+++ a/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@xxxxxxxxx.
#
# support for page migration
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
mm-clarify-compaction-kconfig-text.patch
mm-vmscan-get-rid-of-throttle_vm_writeout.patch
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