mm-memcontrol-remove-hierarchy-restrictions-for-swappiness-and-oom_control-fix

Update Documentation/cgroups/memory.txt

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 2622115276aa028266ae376ff9116401409f433a..1829c65f83714a63d04aeb66752941295601146e 100644 (file)
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -535,17 +535,15 @@ Note:
 
 5.3 swappiness
 
-Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.
+Similar to /proc/sys/vm/swappiness, but only affecting reclaim that is
+triggered by this cgroup's hard limit.  The tunable in the root cgroup
+corresponds to the global swappiness setting.
+
 Please note that unlike the global swappiness, memcg knob set to 0
 really prevents from any swapping even if there is a swap storage
 available. This might lead to memcg OOM killer if there are no file
 pages to reclaim.
 
-Following cgroups' swappiness can't be changed.
-- root cgroup (uses /proc/sys/vm/swappiness).
-- a cgroup which uses hierarchy and it has other cgroup(s) below it.
-- a cgroup which uses hierarchy and not the root of hierarchy.
-
 5.4 failcnt
 
 A memory cgroup provides memory.failcnt and memory.memsw.failcnt files.
@@ -754,7 +752,6 @@ You can disable the OOM-killer by writing "1" to memory.oom_control file, as:
 
        #echo 1 > memory.oom_control
 
-This operation is only allowed to the top cgroup of a sub-hierarchy.
 If OOM-killer is disabled, tasks under cgroup will hang/sleep
 in memory cgroup's OOM-waitqueue when they request accountable memory.