1 files changed, 29 insertions, 3 deletions

diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt
index 6eb1a97e88ce..455d4e6d346d 100644
--- a/Documentation/cgroups/cgroups.txt
+++ b/Documentation/cgroups/cgroups.txt
@@ -408,6 +408,26 @@ You can attach the current shell task by echoing 0:
 
 # echo 0 > tasks
 
+2.3 Mounting hierarchies by name
+--------------------------------
+
+Passing the name=<x> option when mounting a cgroups hierarchy
+associates the given name with the hierarchy.  This can be used when
+mounting a pre-existing hierarchy, in order to refer to it by name
+rather than by its set of active subsystems.  Each hierarchy is either
+nameless, or has a unique name.
+
+The name should match [\w.-]+
+
+When passing a name=<x> option for a new hierarchy, you need to
+specify subsystems manually; the legacy behaviour of mounting all
+subsystems when none are explicitly specified is not supported when
+you give a subsystem a name.
+
+The name of the subsystem appears as part of the hierarchy description
+in /proc/mounts and /proc/<pid>/cgroups.
+
+
 3. Kernel API
 =============
 
@@ -501,7 +521,7 @@ rmdir() will fail with it. From this behavior, pre_destroy() can be
 called multiple times against a cgroup.
 
 int can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-               struct task_struct *task)
+               struct task_struct *task, bool threadgroup)
 (cgroup_mutex held by caller)
 
 Called prior to moving a task into a cgroup; if the subsystem
@@ -509,14 +529,20 @@ returns an error, this will abort the attach operation.  If a NULL
 task is passed, then a successful result indicates that *any*
 unspecified task can be moved into the cgroup. Note that this isn't
 called on a fork. If this method returns 0 (success) then this should
-remain valid while the caller holds cgroup_mutex.
+remain valid while the caller holds cgroup_mutex. If threadgroup is
+true, then a successful result indicates that all threads in the given
+thread's threadgroup can be moved together.
 
 void attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-            struct cgroup *old_cgrp, struct task_struct *task)
+            struct cgroup *old_cgrp, struct task_struct *task,
+            bool threadgroup)
 (cgroup_mutex held by caller)
 
 Called after the task has been attached to the cgroup, to allow any
 post-attachment activity that requires memory allocations or blocking.
+If threadgroup is true, the subsystem should take care of all threads
+in the specified thread's threadgroup. Currently does not support any
+subsystem that might need the old_cgrp for every thread in the group.
 
 void fork(struct cgroup_subsy *ss, struct task_struct *task)