On Tue, Aug 18, 2020 at 12:00 PM Yue Hu <zbest...@gmail.com> wrote:
>
> From: Yue Hu <huy...@yulong.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 remove it and try vzalloc() if kzalloc() fails.
If we can do with vzalloc()'ed memory i.e. we don't need contiguous
physical memory, why even attempt kzalloc?
>
> Signed-off-by: Yue Hu <huy...@yulong.com>
> ---
> drivers/thermal/thermal_sysfs.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
> index aa99edb..9bae0b6 100644
> --- a/drivers/thermal/thermal_sysfs.c
> +++ b/drivers/thermal/thermal_sysfs.c
> @@ -16,6 +16,8 @@
> #include <linux/device.h>
> #include <linux/err.h>
> #include <linux/slab.h>
> +#include <linux/vmalloc.h>
> +#include <linux/mm.h>
> #include <linux/string.h>
> #include <linux/jiffies.h>
>
> @@ -919,7 +921,9 @@ 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 = kzalloc(var, GFP_KERNEL | __GFP_NOWARN);
> + if (!stats)
> + stats = vzalloc(var);
> if (!stats)
> return;
>
> @@ -938,7 +942,7 @@ 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
>
