linux-kernel - [PATCH] thermal: sysfs: Fall back to vmalloc() for cooling device's statistics

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Message-Id: <20200821024406.10404-1-zbestahu@gmail.com>
Date:   Fri, 21 Aug 2020 10:44:05 +0800
From:   Yue Hu <zbestahu@...il.com>
To:     rui.zhang@...el.com, daniel.lezcano@...aro.org,
        amit.kucheria@...durent.com, viresh.kumar@...aro.org
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        huyue2@...ong.com, zhangwen@...ong.com
Subject: [PATCH] thermal: sysfs: Fall back to vmalloc() for cooling device's statistics

From: Yue Hu <huyue2@...ong.com>

We observed warning about kzalloc() when register thermal cooling device
in backlight_device_register(). backlight display can be a cooling device
since reducing screen brightness will can help reduce temperature.

However, ->get_max_state of backlight will assign max brightness of 1024
to states. The memory size can be getting 1MB+ due to states * states.
That is so large to trigger kmalloc() warning.

So, let's use kvzalloc() to avoid the issue, also change kfree -> kvfree.

Suggested-by: Amit Kucheria <amitk@...nel.org>
Signed-off-by: Yue Hu <huyue2@...ong.com>
---
 drivers/thermal/thermal_sysfs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index aa99edb..d1703ee 100644
--- a/drivers/thermal/thermal_sysfs.c
+++ b/drivers/thermal/thermal_sysfs.c
@@ -16,6 +16,7 @@
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/slab.h>
+#include <linux/mm.h>
 #include <linux/string.h>
 #include <linux/jiffies.h>
 
@@ -919,7 +920,7 @@ static void cooling_device_stats_setup(struct thermal_cooling_device *cdev)
 	var += sizeof(*stats->time_in_state) * states;
 	var += sizeof(*stats->trans_table) * states * states;
 
-	stats = kzalloc(var, GFP_KERNEL);
+	stats = kvzalloc(var, GFP_KERNEL);
 	if (!stats)
 		return;
 
@@ -938,7 +939,7 @@ static void cooling_device_stats_setup(struct thermal_cooling_device *cdev)
 
 static void cooling_device_stats_destroy(struct thermal_cooling_device *cdev)
 {
-	kfree(cdev->stats);
+	kvfree(cdev->stats);
 	cdev->stats = NULL;
 }
 
-- 
1.9.1