mm: remove cgroup_mm_owner_callbacks

cgroup_mm_owner_callbacks() was brought in to support the memrlimit
controller, but sneaked into mainline ahead of it.  That controller has
now been shelved, and the mm_owner_changed() args were inadequate for it
anyway (they needed an mm pointer instead of a task pointer).

Remove the dead code, and restore mm_update_next_owner() locking to how it
was before: taking mmap_sem there does nothing for memcontrol.c, now the
only user of mm->owner.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 13 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 1164963c3a8..08b78c09b09 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -329,13 +329,7 @@ struct cgroup_subsys {
                         struct cgroup *cgrp);
         void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
         void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
-        /*
-         * This routine is called with the task_lock of mm->owner held
-         */
-        void (*mm_owner_changed)(struct cgroup_subsys *ss,
-                                        struct cgroup *old,
-                                        struct cgroup *new,
-                                        struct task_struct *p);
+
         int subsys_id;
         int active;
         int disabled;
@@ -400,9 +394,6 @@ void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);
 int cgroup_scan_tasks(struct cgroup_scanner *scan);
 int cgroup_attach_task(struct cgroup *, struct task_struct *);
 
-void cgroup_mm_owner_callbacks(struct task_struct *old,
-                               struct task_struct *new);
-
 #else /* !CONFIG_CGROUPS */
 
 static inline int cgroup_init_early(void) { return 0; }
@@ -420,9 +411,6 @@ static inline int cgroupstats_build(struct cgroupstats *stats,
         return -EINVAL;
 }
 
-static inline void cgroup_mm_owner_callbacks(struct task_struct *old,
-                                             struct task_struct *new) {}
-
 #endif /* !CONFIG_CGROUPS */
 
 #endif /* _LINUX_CGROUP_H */