Re: [PATCH v5] zram: Introduce an aged idle interface

+static void mark_idle(struct zram *zram, ktime_t cutoff)
 {
-	struct zram *zram = dev_to_zram(dev);
+	int is_idle = 1;
 	unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
 	int index;
 
-	if (!sysfs_streq(buf, "all"))
-		return -EINVAL;
-
-	down_read(&zram->init_lock);
-	if (!init_done(zram)) {
-		up_read(&zram->init_lock);
-		return -EINVAL;
-	}
-
 	for (index = 0; index < nr_pages; index++) {
 		/*
 		 * Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race.

@@ -314,14 +308,49 @@ static ssize_t idle_store(struct device *dev,
 		 */
 		zram_slot_lock(zram, index);
 		if (zram_allocated(zram, index) &&
-				!zram_test_flag(zram, index, ZRAM_UNDER_WB))
-			zram_set_flag(zram, index, ZRAM_IDLE);
+				!zram_test_flag(zram, index, ZRAM_UNDER_WB)) {
+#ifdef CONFIG_ZRAM_MEMORY_TRACKING
+				is_idle = (!cutoff || ktime_after(cutoff, zram->table[index].ac_time));

+#endif
+			if (is_idle)
+				zram_set_flag(zram, index, ZRAM_IDLE);
+		}
 		zram_slot_unlock(zram, index);
 	}
+}
 
-	up_read(&zram->init_lock);
+static ssize_t idle_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct zram *zram = dev_to_zram(dev);
+	ktime_t cutoff_time = 0;
+	ssize_t rv = -EINVAL;
 
-	return len;
+	if (!sysfs_streq(buf, "all")) {
+		/*
+		 * If it did not parse as 'all' try to treat it as an integer when
+		 * we have memory tracking enabled.
+		 */
+		u64 age_sec;

+		if (IS_ENABLED(CONFIG_ZRAM_MEMORY_TRACKING) && !kstrtoull(buf, 0, &age_sec))
+			cutoff_time = ktime_sub(ktime_get_boottime(),
+					ns_to_ktime(age_sec * NSEC_PER_SEC));
+		else
+			goto out;
+	}
+
+	down_read(&zram->init_lock);
+	if (!init_done(zram))
+		goto out_unlock;
+
+	/* A age_sec of 0 marks everything as idle, this is the "all" behavior */