oom: remove deprecated oom_adj

The deprecated /proc/<pid>/oom_adj is scheduled for removal this month.

Signed-off-by: Davidlohr Bueso <[e-mail]>
Acked-by: David Rientjes <[e-mail]>
Cc: KOSAKI Motohiro <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/ABI/obsolete/proc-pid-oom_adj

···
-What:	/proc/<pid>/oom_adj
-When:	August 2012
-Why:	/proc/<pid>/oom_adj allows userspace to influence the oom killer's
-	badness heuristic used to determine which task to kill when the kernel
-	is out of memory.
-
-	The badness heuristic has since been rewritten since the introduction of
-	this tunable such that its meaning is deprecated.  The value was
-	implemented as a bitshift on a score generated by the badness()
-	function that did not have any precise units of measure.  With the
-	rewrite, the score is given as a proportion of available memory to the
-	task allocating pages, so using a bitshift which grows the score
-	exponentially is, thus, impossible to tune with fine granularity.
-
-	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
-	/proc/<pid>/oom_adj.
-
-	A warning will be emitted to the kernel log if an application uses this
-	deprecated interface.  After it is printed once, future warnings will be
-	suppressed until the kernel is rebooted.

Documentation/filesystems/proc.txt

···
   2	Modifying System Parameters
 
   3	Per-Process Parameters
-  3.1	/proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer
+  3.1	/proc/<pid>/oom_score_adj - Adjust the oom-killer
 								score
   3.2	/proc/<pid>/oom_score - Display current oom-killer score
   3.3	/proc/<pid>/io - Display the IO accounting fields
···
 CHAPTER 3: PER-PROCESS PARAMETERS
 ------------------------------------------------------------------------------
 
-3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
+3.1 /proc/<pid>/oom_score_adj- Adjust the oom-killer score
 --------------------------------------------------------------------------------
 
-These file can be used to adjust the badness heuristic used to select which
+This file can be used to adjust the badness heuristic used to select which
 process gets killed in out of memory conditions.
 
 The badness heuristic assigns a value to each candidate task ranging from 0
···
 equivalent to discounting 50% of the task's allowed memory from being considered
 as scoring against the task.
 
-For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also
-be used to tune the badness score.  Its acceptable values range from -16
-(OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
-(OOM_DISABLE) to disable oom killing entirely for that task.  Its value is
-scaled linearly with /proc/<pid>/oom_score_adj.
-
-Writing to /proc/<pid>/oom_score_adj or /proc/<pid>/oom_adj will change the
-other with its scaled value.
-
 The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last
 value set by a CAP_SYS_RESOURCE process. To reduce the value any lower
 requires CAP_SYS_RESOURCE.
-
-NOTICE: /proc/<pid>/oom_adj is deprecated and will be removed, please see
-Documentation/feature-removal-schedule.txt.
 
 Caveat: when a parent task is selected, the oom killer will sacrifice any first
 generation children with separate address spaces instead, if possible.  This
···
 -------------------------------------------------------------
 
 This file can be used to check the current score used by the oom-killer is for
-any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which
-process should be killed in an out-of-memory situation.
-
+any given <pid>.
 
 3.3  /proc/<pid>/io - Display the IO accounting fields
 -------------------------------------------------------

fs/proc/base.c

···
 	.release	= mem_release,
 };
 
-static ssize_t oom_adjust_read(struct file *file, char __user *buf,
-				size_t count, loff_t *ppos)
-{
-	struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
-	char buffer[PROC_NUMBUF];
-	size_t len;
-	int oom_adjust = OOM_DISABLE;
-	unsigned long flags;
-
-	if (!task)
-		return -ESRCH;
-
-	if (lock_task_sighand(task, &flags)) {
-		oom_adjust = task->signal->oom_adj;
-		unlock_task_sighand(task, &flags);
-	}
-
-	put_task_struct(task);
-
-	len = snprintf(buffer, sizeof(buffer), "%i\n", oom_adjust);
-
-	return simple_read_from_buffer(buf, count, ppos, buffer, len);
-}
-
-static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
-				size_t count, loff_t *ppos)
-{
-	struct task_struct *task;
-	char buffer[PROC_NUMBUF];
-	int oom_adjust;
-	unsigned long flags;
-	int err;
-
-	memset(buffer, 0, sizeof(buffer));
-	if (count > sizeof(buffer) - 1)
-		count = sizeof(buffer) - 1;
-	if (copy_from_user(buffer, buf, count)) {
-		err = -EFAULT;
-		goto out;
-	}
-
-	err = kstrtoint(strstrip(buffer), 0, &oom_adjust);
-	if (err)
-		goto out;
-	if ((oom_adjust < OOM_ADJUST_MIN || oom_adjust > OOM_ADJUST_MAX) &&
-	     oom_adjust != OOM_DISABLE) {
-		err = -EINVAL;
-		goto out;
-	}
-
-	task = get_proc_task(file->f_path.dentry->d_inode);
-	if (!task) {
-		err = -ESRCH;
-		goto out;
-	}
-
-	task_lock(task);
-	if (!task->mm) {
-		err = -EINVAL;
-		goto err_task_lock;
-	}
-
-	if (!lock_task_sighand(task, &flags)) {
-		err = -ESRCH;
-		goto err_task_lock;
-	}
-
-	if (oom_adjust < task->signal->oom_adj && !capable(CAP_SYS_RESOURCE)) {
-		err = -EACCES;
-		goto err_sighand;
-	}
-
-	/*
-	 * Warn that /proc/pid/oom_adj is deprecated, see
-	 * Documentation/feature-removal-schedule.txt.
-	 */
-	printk_once(KERN_WARNING "%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",
-		  current->comm, task_pid_nr(current), task_pid_nr(task),
-		  task_pid_nr(task));
-	task->signal->oom_adj = oom_adjust;
-	/*
-	 * Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum
-	 * value is always attainable.
-	 */
-	if (task->signal->oom_adj == OOM_ADJUST_MAX)
-		task->signal->oom_score_adj = OOM_SCORE_ADJ_MAX;
-	else
-		task->signal->oom_score_adj = (oom_adjust * OOM_SCORE_ADJ_MAX) /
-								-OOM_DISABLE;
-	trace_oom_score_adj_update(task);
-err_sighand:
-	unlock_task_sighand(task, &flags);
-err_task_lock:
-	task_unlock(task);
-	put_task_struct(task);
-out:
-	return err < 0 ? err : count;
-}
-
-static const struct file_operations proc_oom_adjust_operations = {
-	.read		= oom_adjust_read,
-	.write		= oom_adjust_write,
-	.llseek		= generic_file_llseek,
-};
-
 static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
 					size_t count, loff_t *ppos)
 {
···
 	if (has_capability_noaudit(current, CAP_SYS_RESOURCE))
 		task->signal->oom_score_adj_min = oom_score_adj;
 	trace_oom_score_adj_update(task);
-	/*
-	 * Scale /proc/pid/oom_adj appropriately ensuring that OOM_DISABLE is
-	 * always attainable.
-	 */
-	if (task->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
-		task->signal->oom_adj = OOM_DISABLE;
-	else
-		task->signal->oom_adj = (oom_score_adj * OOM_ADJUST_MAX) /
-							OOM_SCORE_ADJ_MAX;
+
 err_sighand:
 	unlock_task_sighand(task, &flags);
 err_task_lock:
···
 	REG("cgroup",  S_IRUGO, proc_cgroup_operations),
 #endif
 	INF("oom_score",  S_IRUGO, proc_oom_score),
-	REG("oom_adj",    S_IRUGO|S_IWUSR, proc_oom_adjust_operations),
 	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
 #ifdef CONFIG_AUDITSYSCALL
 	REG("loginuid",   S_IWUSR|S_IRUGO, proc_loginuid_operations),
···
 	REG("cgroup",  S_IRUGO, proc_cgroup_operations),
 #endif
 	INF("oom_score", S_IRUGO, proc_oom_score),
-	REG("oom_adj",   S_IRUGO|S_IWUSR, proc_oom_adjust_operations),
 	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
 #ifdef CONFIG_AUDITSYSCALL
 	REG("loginuid",  S_IWUSR|S_IRUGO, proc_loginuid_operations),

include/linux/oom.h

···
 #define __INCLUDE_LINUX_OOM_H
 
 /*
- * /proc/<pid>/oom_adj is deprecated, see
- * Documentation/feature-removal-schedule.txt.
- *
- * /proc/<pid>/oom_adj set to -17 protects from the oom-killer
- */
-#define OOM_DISABLE (-17)
-/* inclusive */
-#define OOM_ADJUST_MIN (-16)
-#define OOM_ADJUST_MAX 15
-
-/*
  * /proc/<pid>/oom_score_adj set to OOM_SCORE_ADJ_MIN disables oom killing for
  * pid.
  */

include/linux/sched.h

···
 	struct rw_semaphore group_rwsem;
 #endif
 
-	int oom_adj;		/* OOM kill score adjustment (bit shift) */
 	int oom_score_adj;	/* OOM kill score adjustment */
 	int oom_score_adj_min;	/* OOM kill score adjustment minimum value.
 				 * Only settable by CAP_SYS_RESOURCE. */

kernel/fork.c

···
 	init_rwsem(&sig->group_rwsem);
 #endif
 
-	sig->oom_adj = current->signal->oom_adj;
 	sig->oom_score_adj = current->signal->oom_score_adj;
 	sig->oom_score_adj_min = current->signal->oom_score_adj_min;
 

mm/oom_kill.c

···
 {
 	task_lock(current);
 	pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
-		"oom_adj=%d, oom_score_adj=%d\n",
-		current->comm, gfp_mask, order, current->signal->oom_adj,
+		"oom_score_adj=%d\n",
+		current->comm, gfp_mask, order,
 		current->signal->oom_score_adj);
 	cpuset_print_task_mems_allowed(current);
 	task_unlock(current);