[PATCH 2/2] mm: Fix documentation of min_unmapped_ratio

[Mel Gorman <mel@csn.ul.ie>]

Kosaki Motohiro pointed out that the documentation for
min_unmapped_ratio no longer matches the implementation. This patch
updates the documentation.

This patch can be merged with
vmscan-properly-account-for-the-number-of-page-cache-pages-zone_reclaim-can-re
claim.patch .

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
---
 Documentation/sysctl/vm.txt |   12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 0ea5adb..c4de635 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -315,10 +315,14 @@ min_unmapped_ratio:
 
 This is available only on NUMA kernels.
 
-A percentage of the total pages in each zone.  Zone reclaim will only
-occur if more than this percentage of pages are file backed and unmapped.
-This is to insure that a minimal amount of local pages is still available for
-file I/O even if the node is overallocated.
+This is a percentage of the total pages in each zone. Zone reclaim will
+only occur if more than this percentage of pages are in a state that
+zone_reclaim_mode allows to be reclaimed.
+
+If zone_reclaim_mode has the value 4 OR'd, then the percentage is compared
+against all file-backed unmapped pages including swapcache pages and tmpfs
+files. Otherwise, only unmapped pages backed by normal files but not tmpfs
+files and similar are considered.
 
 The default is 1 percent.
 
-- 
1.5.6.5

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