On 2016/5/5 16:32, Michal Hocko wrote:

On Thu 05-05-16 16:15:01, Qiang Huang wrote:

quoted

We don't have this restriction for a long time, docs should
be fixed.

Signed-off-by: Qiang Huang <redacted>
---
 Documentation/cgroup-v1/memory.txt | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/Documentation/cgroup-v1/memory.txt b/Documentation/cgroup-v1/memory.txt
index ff71e16..d45b201 100644
--- a/Documentation/cgroup-v1/memory.txt
+++ b/Documentation/cgroup-v1/memory.txt

@@ -281,11 +281,9 @@ different than user memory, since it can't be swapped out, which makes it
 possible to DoS the system by consuming too much of this precious resource.
 
 Kernel memory won't be accounted at all until limit on a group is set. This
-allows for existing setups to continue working without disruption.  The limit
-cannot be set if the cgroup have children, or if there are already tasks in the
-cgroup. Attempting to set the limit under those conditions will return -EBUSY.
-When use_hierarchy == 1 and a group is accounted, its children will
-automatically be accounted regardless of their limit value.
+allows for existing setups to continue working without disruption. When
+use_hierarchy == 1 and a group is accounted, its children will automatically
+be accounted regardless of their limit value.

The restriction is not there anymore because the accounting is enabled
by default even in the cgroup v1 - see b313aeee2509 ("mm: memcontrol:
enable kmem accounting for all cgroups in the legacy hierarchy"). So
this _whole_ paragraph could see some update.

Sorry for the delay.
Thanks for the hint, I'll sent a new patch soon.