mm, oom: change type of oom_score_adj to short

The maximum oom_score_adj is 1000 and the minimum oom_score_adj is -1000,
so this range can be represented by the signed short type with no
functional change.  The extra space this frees up in struct signal_struct
will be used for per-thread oom kill flags in the next patch.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/staging/android/lowmemorykiller.c

@@ -40,7 +40,7 @@
 #include <linux/notifier.h>
 
 static uint32_t lowmem_debug_level = 2;
-static int lowmem_adj[6] = {
+static short lowmem_adj[6] = {
 	0,
 	1,
 	6,
@@ -70,9 +70,9 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
 	int rem = 0;
 	int tasksize;
 	int i;
-	int min_score_adj = OOM_SCORE_ADJ_MAX + 1;
+	short min_score_adj = OOM_SCORE_ADJ_MAX + 1;
 	int selected_tasksize = 0;
-	int selected_oom_score_adj;
+	short selected_oom_score_adj;
 	int array_size = ARRAY_SIZE(lowmem_adj);
 	int other_free = global_page_state(NR_FREE_PAGES);
 	int other_file = global_page_state(NR_FILE_PAGES) -
@@ -90,7 +90,7 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
 		}
 	}
 	if (sc->nr_to_scan > 0)
-		lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %d\n",
+		lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %hd\n",
 				sc->nr_to_scan, sc->gfp_mask, other_free,
 				other_file, min_score_adj);
 	rem = global_page_state(NR_ACTIVE_ANON) +
@@ -107,7 +107,7 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
 	rcu_read_lock();
 	for_each_process(tsk) {
 		struct task_struct *p;
-		int oom_score_adj;
+		short oom_score_adj;
 
 		if (tsk->flags & PF_KTHREAD)
 			continue;
@@ -141,11 +141,11 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
 		selected = p;
 		selected_tasksize = tasksize;
 		selected_oom_score_adj = oom_score_adj;
-		lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
+		lowmem_print(2, "select %d (%s), adj %hd, size %d, to kill\n",
 			     p->pid, p->comm, oom_score_adj, tasksize);
 	}
 	if (selected) {
-		lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
+		lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n",
 			     selected->pid, selected->comm,
 			     selected_oom_score_adj, selected_tasksize);
 		lowmem_deathpending_timeout = jiffies + HZ;
@@ -176,7 +176,7 @@ static void __exit lowmem_exit(void)
 }
 
 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
-module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
+module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size,
 			 S_IRUGO | S_IWUSR);
 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 			 S_IRUGO | S_IWUSR);

fs/proc/base.c

@@ -985,7 +985,7 @@ static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
 {
 	struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
 	char buffer[PROC_NUMBUF];
-	int oom_score_adj = OOM_SCORE_ADJ_MIN;
+	short oom_score_adj = OOM_SCORE_ADJ_MIN;
 	unsigned long flags;
 	size_t len;
 
@@ -996,7 +996,7 @@ static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
 		unlock_task_sighand(task, &flags);
 	}
 	put_task_struct(task);
-	len = snprintf(buffer, sizeof(buffer), "%d\n", oom_score_adj);
+	len = snprintf(buffer, sizeof(buffer), "%hd\n", oom_score_adj);
 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
 }
 
@@ -1043,15 +1043,15 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
 		goto err_task_lock;
 	}
 
-	if (oom_score_adj < task->signal->oom_score_adj_min &&
+	if ((short)oom_score_adj < task->signal->oom_score_adj_min &&
 			!capable(CAP_SYS_RESOURCE)) {
 		err = -EACCES;
 		goto err_sighand;
 	}
 
-	task->signal->oom_score_adj = oom_score_adj;
+	task->signal->oom_score_adj = (short)oom_score_adj;
 	if (has_capability_noaudit(current, CAP_SYS_RESOURCE))
-		task->signal->oom_score_adj_min = oom_score_adj;
+		task->signal->oom_score_adj_min = (short)oom_score_adj;
 	trace_oom_score_adj_update(task);
 
 err_sighand:

include/linux/oom.h

@@ -29,8 +29,8 @@ enum oom_scan_t {
 	OOM_SCAN_SELECT,	/* always select this thread first */
 };
 
-extern void compare_swap_oom_score_adj(int old_val, int new_val);
-extern int test_set_oom_score_adj(int new_val);
+extern void compare_swap_oom_score_adj(short old_val, short new_val);
+extern short test_set_oom_score_adj(short new_val);
 
 extern unsigned long oom_badness(struct task_struct *p,
 		struct mem_cgroup *memcg, const nodemask_t *nodemask,

include/linux/sched.h

@@ -631,9 +631,9 @@ struct signal_struct {
 	struct rw_semaphore group_rwsem;
 #endif
 
-	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. */
+	short oom_score_adj;		/* OOM kill score adjustment */
+	short oom_score_adj_min;	/* OOM kill score adjustment min value.
+					 * Only settable by CAP_SYS_RESOURCE. */
 
 	struct mutex cred_guard_mutex;	/* guard against foreign influences on
 					 * credential calculations

include/trace/events/oom.h

@@ -14,7 +14,7 @@ TRACE_EVENT(oom_score_adj_update,
 	TP_STRUCT__entry(
 		__field(	pid_t,	pid)
 		__array(	char,	comm,	TASK_COMM_LEN )
-		__field(	 int,	oom_score_adj)
+		__field(	short,	oom_score_adj)
 	),
 
 	TP_fast_assign(
@@ -23,7 +23,7 @@ TRACE_EVENT(oom_score_adj_update,
 		__entry->oom_score_adj = task->signal->oom_score_adj;
 	),
 
-	TP_printk("pid=%d comm=%s oom_score_adj=%d",
+	TP_printk("pid=%d comm=%s oom_score_adj=%hd",
 		__entry->pid, __entry->comm, __entry->oom_score_adj)
 );
 

include/trace/events/task.h

@@ -15,7 +15,7 @@ TRACE_EVENT(task_newtask,
 		__field(	pid_t,	pid)
 		__array(	char,	comm, TASK_COMM_LEN)
 		__field( unsigned long, clone_flags)
-		__field(	int,    oom_score_adj)
+		__field(	short,	oom_score_adj)
 	),
 
 	TP_fast_assign(
@@ -25,7 +25,7 @@ TRACE_EVENT(task_newtask,
 		__entry->oom_score_adj = task->signal->oom_score_adj;
 	),
 
-	TP_printk("pid=%d comm=%s clone_flags=%lx oom_score_adj=%d",
+	TP_printk("pid=%d comm=%s clone_flags=%lx oom_score_adj=%hd",
 		__entry->pid, __entry->comm,
 		__entry->clone_flags, __entry->oom_score_adj)
 );
@@ -40,7 +40,7 @@ TRACE_EVENT(task_rename,
 		__field(	pid_t,	pid)
 		__array(	char, oldcomm,  TASK_COMM_LEN)
 		__array(	char, newcomm,  TASK_COMM_LEN)
-		__field(	int, oom_score_adj)
+		__field(	short,	oom_score_adj)
 	),
 
 	TP_fast_assign(
@@ -50,7 +50,7 @@ TRACE_EVENT(task_rename,
 		__entry->oom_score_adj = task->signal->oom_score_adj;
 	),
 
-	TP_printk("pid=%d oldcomm=%s newcomm=%s oom_score_adj=%d",
+	TP_printk("pid=%d oldcomm=%s newcomm=%s oom_score_adj=%hd",
 		__entry->pid, __entry->oldcomm,
 		__entry->newcomm, __entry->oom_score_adj)
 );

mm/ksm.c

@@ -1919,7 +1919,7 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr,
 	if (ksm_run != flags) {
 		ksm_run = flags;
 		if (flags & KSM_RUN_UNMERGE) {
-			int oom_score_adj;
+			short oom_score_adj;
 
 			oom_score_adj = test_set_oom_score_adj(OOM_SCORE_ADJ_MAX);
 			err = unmerge_and_remove_all_rmap_items();

mm/oom_kill.c

@@ -53,7 +53,7 @@ static DEFINE_SPINLOCK(zone_scan_lock);
  * @old_val.  Usually used to reinstate a previous value to prevent racing with
  * userspacing tuning the value in the interim.
  */
-void compare_swap_oom_score_adj(int old_val, int new_val)
+void compare_swap_oom_score_adj(short old_val, short new_val)
 {
 	struct sighand_struct *sighand = current->sighand;
 
@@ -72,7 +72,7 @@ void compare_swap_oom_score_adj(int old_val, int new_val)
  * synchronization and returns the old value.  Usually used to temporarily
  * set a value, save the old value in the caller, and then reinstate it later.
  */
-int test_set_oom_score_adj(int new_val)
+short test_set_oom_score_adj(short new_val)
 {
 	struct sighand_struct *sighand = current->sighand;
 	int old_val;
@@ -193,7 +193,7 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
 	if (!p)
 		return 0;
 
-	adj = p->signal->oom_score_adj;
+	adj = (long)p->signal->oom_score_adj;
 	if (adj == OOM_SCORE_ADJ_MIN) {
 		task_unlock(p);
 		return 0;
@@ -399,7 +399,7 @@ static void dump_tasks(const struct mem_cgroup *memcg, const nodemask_t *nodemas
 			continue;
 		}
 
-		pr_info("[%5d] %5d %5d %8lu %8lu %7lu %8lu         %5d %s\n",
+		pr_info("[%5d] %5d %5d %8lu %8lu %7lu %8lu         %5hd %s\n",
 			task->pid, from_kuid(&init_user_ns, task_uid(task)),
 			task->tgid, task->mm->total_vm, get_mm_rss(task->mm),
 			task->mm->nr_ptes,
@@ -415,7 +415,7 @@ static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
 {
 	task_lock(current);
 	pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
-		"oom_score_adj=%d\n",
+		"oom_score_adj=%hd\n",
 		current->comm, gfp_mask, order,
 		current->signal->oom_score_adj);
 	cpuset_print_task_mems_allowed(current);

mm/swapfile.c

@@ -1498,7 +1498,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	struct address_space *mapping;
 	struct inode *inode;
 	struct filename *pathname;
-	int oom_score_adj;
+	short oom_score_adj;
 	int i, type, prev;
 	int err;