oom: remove references to old badness() function

The badness() function in the oom killer was renamed to oom_badness() in
a63d83f427fb ("oom: badness heuristic rewrite") since it is a globally
exported function for clarity.

The prototype for the old function still existed in linux/oom.h, so remove
it.  There are no existing users.

Also fixes documentation and comment references to badness() and adjusts
them accordingly.

Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/ABI/obsolete/proc-pid-oom_adj

@@ -14,7 +14,7 @@ Why:	/proc/<pid>/oom_adj allows userspace to influence the oom killer's
 
 	A much more powerful interface, /proc/<pid>/oom_score_adj, was
 	introduced with the oom killer rewrite that allows users to increase or
-	decrease the badness() score linearly.  This interface will replace
+	decrease the badness score linearly.  This interface will replace
 	/proc/<pid>/oom_adj.
 
 	A warning will be emitted to the kernel log if an application uses this

Documentation/feature-removal-schedule.txt

@@ -184,7 +184,7 @@ Why:	/proc/<pid>/oom_adj allows userspace to influence the oom killer's
 
 	A much more powerful interface, /proc/<pid>/oom_score_adj, was
 	introduced with the oom killer rewrite that allows users to increase or
-	decrease the badness() score linearly.  This interface will replace
+	decrease the badness score linearly.  This interface will replace
 	/proc/<pid>/oom_adj.
 
 	A warning will be emitted to the kernel log if an application uses this

include/linux/oom.h

@@ -64,10 +64,6 @@ static inline void oom_killer_enable(void)
 	oom_killer_disabled = false;
 }
 
-/* The badness from the OOM killer */
-extern unsigned long badness(struct task_struct *p, struct mem_cgroup *mem,
-		      const nodemask_t *nodemask, unsigned long uptime);
-
 extern struct task_struct *find_lock_task_mm(struct task_struct *p);
 
 /* sysctls */

mm/oom_kill.c

@@ -487,7 +487,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 
 	/*
 	 * If any of p's children has a different mm and is eligible for kill,
-	 * the one with the highest badness() score is sacrificed for its
+	 * the one with the highest oom_badness() score is sacrificed for its
 	 * parent.  This attempts to lose the minimal amount of work done while
 	 * still freeing memory.
 	 */