[PATCH] idea

[Lorenzo Stoakes (Oracle)]

Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@xxxxxxxxxx>
---
 mm/huge_memory.c | 74 ++++++++++++++++++++++++++++++------------------
 1 file changed, 46 insertions(+), 28 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 0df1f4a17430..97dabbeb9112 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -515,46 +515,64 @@ static ssize_t anon_enabled_show(struct kobject *kobj,
 	return sysfs_emit(buf, "%s\n", output);
 }

+enum huge_mode {
+	HUGE_ALWAYS,
+	HUGE_INHERIT,
+	HUGE_MADVISE,
+	HUGE_NUM_MODES,
+	HUGE_NEVER,
+};
+
+static bool change_anon_orders(int order, enum huge_mode mode)
+{
+	static unsigned long *orders[] = {
+		&huge_anon_orders_always,
+		&huge_anon_orders_inherit,
+		&huge_anon_orders_madvise,
+	};
+	bool changed = false;
+	int i;
+
+	spin_lock(&huge_anon_orders_lock);
+	for (i = 0; i < HUGE_NUM_MODES; i++) {
+		if (i == mode)
+			changed |= !test_and_set_bit(order, orders[mode]);
+		else
+			changed |= test_and_clear_bit(order, orders[mode]);
+	}
+	spin_unlock(&huge_anon_orders_lock);
+
+	return changed;
+}
+
 static ssize_t anon_enabled_store(struct kobject *kobj,
 				 struct kobj_attribute *attr,
 				 const char *buf, size_t count)
 {
 	int order = to_thpsize(kobj)->order;
 	ssize_t ret = count;
+	bool changed;
+
+	if (sysfs_streq(buf, "always"))
+		changed = change_anon_orders(order, HUGE_ALWAYS);
+	else if (sysfs_streq(buf, "inherit"))
+		changed = change_anon_orders(order, HUGE_INHERIT);
+	else if (sysfs_streq(buf, "madvise"))
+		changed = change_anon_orders(order, HUGE_MADVISE);
+	else if (sysfs_streq(buf, "never"))
+		changed = change_anon_orders(order, HUGE_NEVER);
+	else
+		return -EINVAL;

-	if (sysfs_streq(buf, "always")) {
-		spin_lock(&huge_anon_orders_lock);
-		clear_bit(order, &huge_anon_orders_inherit);
-		clear_bit(order, &huge_anon_orders_madvise);
-		set_bit(order, &huge_anon_orders_always);
-		spin_unlock(&huge_anon_orders_lock);
-	} else if (sysfs_streq(buf, "inherit")) {
-		spin_lock(&huge_anon_orders_lock);
-		clear_bit(order, &huge_anon_orders_always);
-		clear_bit(order, &huge_anon_orders_madvise);
-		set_bit(order, &huge_anon_orders_inherit);
-		spin_unlock(&huge_anon_orders_lock);
-	} else if (sysfs_streq(buf, "madvise")) {
-		spin_lock(&huge_anon_orders_lock);
-		clear_bit(order, &huge_anon_orders_always);
-		clear_bit(order, &huge_anon_orders_inherit);
-		set_bit(order, &huge_anon_orders_madvise);
-		spin_unlock(&huge_anon_orders_lock);
-	} else if (sysfs_streq(buf, "never")) {
-		spin_lock(&huge_anon_orders_lock);
-		clear_bit(order, &huge_anon_orders_always);
-		clear_bit(order, &huge_anon_orders_inherit);
-		clear_bit(order, &huge_anon_orders_madvise);
-		spin_unlock(&huge_anon_orders_lock);
-	} else
-		ret = -EINVAL;
-
-	if (ret > 0) {
+	if (changed) {
 		int err;

 		err = start_stop_khugepaged();
 		if (err)
 			ret = err;
+	} else {
+		/* Users expect this even if unchanged. TODO: Put in header... */
+		//set_recommended_min_free_kbytes();
 	}
 	return ret;
 }
--
2.53.0