memcg: kill CONFIG_MM_OWNER

CONFIG_MM_OWNER makes no sense.  It is not user-selectable, it is only
selected by CONFIG_MEMCG automatically.  So we can kill this option in
init/Kconfig and do s/CONFIG_MM_OWNER/CONFIG_MEMCG/ globally.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm_types.h

@@ -406,7 +406,7 @@ struct mm_struct {
 	spinlock_t			ioctx_lock;
 	struct kioctx_table __rcu	*ioctx_table;
 #endif
-#ifdef CONFIG_MM_OWNER
+#ifdef CONFIG_MEMCG
 	/*
 	 * "owner" points to a task that is regarded as the canonical
 	 * user/owner of this mm. All of the following must be true in

include/linux/sched.h

@@ -2967,7 +2967,7 @@ static inline void inc_syscw(struct task_struct *tsk)
 #define TASK_SIZE_OF(tsk)	TASK_SIZE
 #endif
 
-#ifdef CONFIG_MM_OWNER
+#ifdef CONFIG_MEMCG
 extern void mm_update_next_owner(struct mm_struct *mm);
 extern void mm_init_owner(struct mm_struct *mm, struct task_struct *p);
 #else
@@ -2978,7 +2978,7 @@ static inline void mm_update_next_owner(struct mm_struct *mm)
 static inline void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
 {
 }
-#endif /* CONFIG_MM_OWNER */
+#endif /* CONFIG_MEMCG */
 
 static inline unsigned long task_rlimit(const struct task_struct *tsk,
 		unsigned int limit)

init/Kconfig

@@ -933,7 +933,6 @@ config RESOURCE_COUNTERS
 config MEMCG
 	bool "Memory Resource Controller for Control Groups"
 	depends on RESOURCE_COUNTERS
-	select MM_OWNER
 	select EVENTFD
 	help
 	  Provides a memory resource controller that manages both anonymous
@@ -951,9 +950,6 @@ config MEMCG
 	  disable memory resource controller and you can avoid overheads.
 	  (and lose benefits of memory resource controller)
 
-	  This config option also selects MM_OWNER config option, which
-	  could in turn add some fork/exit overhead.
-
 config MEMCG_SWAP
 	bool "Memory Resource Controller Swap Extension"
 	depends on MEMCG && SWAP
@@ -1179,9 +1175,6 @@ config SCHED_AUTOGROUP
 	  desktop applications.  Task group autogeneration is currently based
 	  upon task session.
 
-config MM_OWNER
-	bool
-
 config SYSFS_DEPRECATED
 	bool "Enable deprecated sysfs features to support old userspace tools"
 	depends on SYSFS

kernel/exit.c

@@ -352,7 +352,7 @@ int disallow_signal(int sig)
 
 EXPORT_SYMBOL(disallow_signal);
 
-#ifdef CONFIG_MM_OWNER
+#ifdef CONFIG_MEMCG
 /*
  * A task is exiting.   If it owned this mm, find a new owner for the mm.
  */
@@ -434,7 +434,7 @@ void mm_update_next_owner(struct mm_struct *mm)
 	task_unlock(c);
 	put_task_struct(c);
 }
-#endif /* CONFIG_MM_OWNER */
+#endif /* CONFIG_MEMCG */
 
 /*
  * Turn us into a lazy TLB process if we

kernel/fork.c

@@ -1099,12 +1099,12 @@ static void rt_mutex_init_task(struct task_struct *p)
 #endif
 }
 
-#ifdef CONFIG_MM_OWNER
+#ifdef CONFIG_MEMCG
 void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
 {
 	mm->owner = p;
 }
-#endif /* CONFIG_MM_OWNER */
+#endif /* CONFIG_MEMCG */
 
 /*
  * Initialize POSIX timer handling for a single task.