Merge tag 'mfd-for-linus-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/lee...

[cascardo/linux.git] / Documentation / cgroups / memory.txt

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 2622115..4937e6f 100644 (file)
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -270,6 +270,11 @@ When oom event notifier is registered, event will be delivered.
 
 2.7 Kernel Memory Extension (CONFIG_MEMCG_KMEM)
 
+WARNING: Current implementation lacks reclaim support. That means allocation
+        attempts will fail when close to the limit even if there are plenty of
+        kmem available for reclaim. That makes this option unusable in real
+        life so DO NOT SELECT IT unless for development purposes.
+
 With the Kernel memory extension, the Memory Controller is able to limit
 the amount of kernel memory used by the system. Kernel memory is fundamentally
 different than user memory, since it can't be swapped out, which makes it
@@ -535,17 +540,15 @@ 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 +757,6 @@ 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.