Merge branch 'for-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup updates from Tejun Heo:
 "A lot of activities on the cgroup front.  Most changes aren't visible
  to userland at all at this point and are laying foundation for the
  planned unified hierarchy.

   - The biggest change is decoupling the lifetime management of css
     (cgroup_subsys_state) from that of cgroup's.  Because controllers
     (cpu, memory, block and so on) will need to be dynamically enabled
     and disabled, css which is the association point between a cgroup
     and a controller may come and go dynamically across the lifetime of
     a cgroup.  Till now, css's were created when the associated cgroup
     was created and stayed till the cgroup got destroyed.

     Assumptions around this tight coupling permeated through cgroup
     core and controllers.  These assumptions are gradually removed,
     which consists bulk of patches, and css destruction path is
     completely decoupled from cgroup destruction path.  Note that
     decoupling of creation path is relatively easy on top of these
     changes and the patchset is pending for the next window.

   - cgroup has its own event mechanism cgroup.event_control, which is
     only used by memcg.  It is overly complex trying to achieve high
     flexibility whose benefits seem dubious at best.  Going forward,
     new events will simply generate file modified event and the
     existing mechanism is being made specific to memcg.  This pull
     request contains prepatory patches for such change.

   - Various fixes and cleanups"

Fixed up conflict in kernel/cgroup.c as per Tejun.

* 'for-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (69 commits)
  cgroup: fix cgroup_css() invocation in css_from_id()
  cgroup: make cgroup_write_event_control() use css_from_dir() instead of __d_cgrp()
  cgroup: make cgroup_event hold onto cgroup_subsys_state instead of cgroup
  cgroup: implement CFTYPE_NO_PREFIX
  cgroup: make cgroup_css() take cgroup_subsys * instead and allow NULL subsys
  cgroup: rename cgroup_css_from_dir() to css_from_dir() and update its syntax
  cgroup: fix cgroup_write_event_control()
  cgroup: fix subsystem file accesses on the root cgroup
  cgroup: change cgroup_from_id() to css_from_id()
  cgroup: use css_get() in cgroup_create() to check CSS_ROOT
  cpuset: remove an unncessary forward declaration
  cgroup: RCU protect each cgroup_subsys_state release
  cgroup: move subsys file removal to kill_css()
  cgroup: factor out kill_css()
  cgroup: decouple cgroup_subsys_state destruction from cgroup destruction
  cgroup: replace cgroup->css_kill_cnt with ->nr_css
  cgroup: bounce cgroup_subsys_state ref kill confirmation to a work item
  cgroup: move cgroup->subsys[] assignment to online_css()
  cgroup: reorganize css init / exit paths
  cgroup: add __rcu modifier to cgroup->subsys[]
  ...

1 files changed, 11 insertions, 14 deletions

diff --git a/mm/vmpressure.c b/mm/vmpressure.c
index 0c1e37d..e0f6283 100644
--- a/mm/vmpressure.c
+++ b/mm/vmpressure.c
@@ -74,15 +74,10 @@ static struct vmpressure *work_to_vmpressure(struct work_struct *work)
 	return container_of(work, struct vmpressure, work);
 }
 
-static struct vmpressure *cg_to_vmpressure(struct cgroup *cg)
-{
-	return css_to_vmpressure(cgroup_subsys_state(cg, mem_cgroup_subsys_id));
-}
-
 static struct vmpressure *vmpressure_parent(struct vmpressure *vmpr)
 {
-	struct cgroup *cg = vmpressure_to_css(vmpr)->cgroup;
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cg);
+	struct cgroup_subsys_state *css = vmpressure_to_css(vmpr);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 
 	memcg = parent_mem_cgroup(memcg);
 	if (!memcg)
@@ -283,7 +278,7 @@ void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio)
 
 /**
  * vmpressure_register_event() - Bind vmpressure notifications to an eventfd
- * @cg:		cgroup that is interested in vmpressure notifications
+ * @css:	css that is interested in vmpressure notifications
  * @cft:	cgroup control files handle
  * @eventfd:	eventfd context to link notifications with
  * @args:	event arguments (used to set up a pressure level threshold)
@@ -298,10 +293,11 @@ void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio)
  * cftype).register_event, and then cgroup core will handle everything by
  * itself.
  */
-int vmpressure_register_event(struct cgroup *cg, struct cftype *cft,
-			      struct eventfd_ctx *eventfd, const char *args)
+int vmpressure_register_event(struct cgroup_subsys_state *css,
+			      struct cftype *cft, struct eventfd_ctx *eventfd,
+			      const char *args)
 {
-	struct vmpressure *vmpr = cg_to_vmpressure(cg);
+	struct vmpressure *vmpr = css_to_vmpressure(css);
 	struct vmpressure_event *ev;
 	int level;
 
@@ -329,7 +325,7 @@ int vmpressure_register_event(struct cgroup *cg, struct cftype *cft,
 
 /**
  * vmpressure_unregister_event() - Unbind eventfd from vmpressure
- * @cg:		cgroup handle
+ * @css:	css handle
  * @cft:	cgroup control files handle
  * @eventfd:	eventfd context that was used to link vmpressure with the @cg
  *
@@ -341,10 +337,11 @@ int vmpressure_register_event(struct cgroup *cg, struct cftype *cft,
  * cftype).unregister_event, and then cgroup core will handle everything
  * by itself.
  */
-void vmpressure_unregister_event(struct cgroup *cg, struct cftype *cft,
+void vmpressure_unregister_event(struct cgroup_subsys_state *css,
+				 struct cftype *cft,
 				 struct eventfd_ctx *eventfd)
 {
-	struct vmpressure *vmpr = cg_to_vmpressure(cg);
+	struct vmpressure *vmpr = css_to_vmpressure(css);
 	struct vmpressure_event *ev;
 
 	mutex_lock(&vmpr->events_lock);