Re: [ISSUE] Memleak in LED sysfs on heavy usage

[Daniel Gorsulowski]

Hi Jacek,

Am 16.09.2016 um 09:31 schrieb Jacek Anaszewski:
> Hi Daniel,
>
> On 09/12/2016 10:50 AM, Daniel Gorsulowski wrote:
> > Hello!
> >
> > Please consider if I made something wrong, sending this issue. This is
> > my first contact to the LKML.
> > By mistake, I accessed an LED via /sys/class/leds subsystem very fast in
> > an user application. I figured out, that the free user memory decreased
> > constantly. So I tried to analyze the Problem and wrote a litte script:
> >
> > #!/bin/sh
> > while [ 1 ]; do
> >         echo 1 > /sys/class/leds/2a_service_yellow/brightness
> >         echo 0 > /sys/class/leds/2a_service_yellow/brightness
> > done
> >
> > And voila, I was able to reproduce the problem.
> > So I add a bit more debugging:
> >
> > #!/bin/sh
> > cnt=0
> > while [ 1 ]; do
> >         if [ `expr $cnt % 1000` -eq 0 ]; then
> >                 free | grep Mem: | cut -d' ' -f25
> >         fi
> >         echo 1 > /sys/class/leds/2a_service_yellow/brightness
> >         echo 0 > /sys/class/leds/2a_service_yellow/brightness
> >         let "cnt++"
> > done
> >
> > And huh? No memory is eaten anymore. So it looks like, the problem only
> > occours on heavy (fast) usage of /sys/class/leds subsystem.
> >
> > I rewrote the script and toggled a GPIO pin, but there was no problem
> > recognizable.
>
> I've been unable to reproduce the problem with leds-aat1290 driver
> and Samsung M0 board. It must be driver specific issue.
> What driver did you use?
I defined LEDS_GPIO and so I'm using leds-gpio driver.
danielg@debby:~/opt/prj/ti-linux-kernel$ cat .config | grep LEDS | grep 
-v "^# "
CONFIG_INPUT_LEDS=y
CONFIG_NEW_LEDS=y
CONFIG_LEDS_CLASS=y
CONFIG_LEDS_GPIO=y
CONFIG_LEDS_TRIGGERS=y
CONFIG_LEDS_TRIGGER_TIMER=y
CONFIG_LEDS_TRIGGER_ONESHOT=y
CONFIG_LEDS_TRIGGER_HEARTBEAT=y
CONFIG_LEDS_TRIGGER_GPIO=y
CONFIG_LEDS_TRIGGER_DEFAULT_ON=y
CONFIG_LEDS_TRIGGER_TRANSIENT=y

> > Some details about my test environment:
> > Hardware: Ti Sitara AM3357ZCZ with 128MiB memory
> > Kernel: vanilla 4.6
> >
> > The relevant part of my .dts:
> > #include "am33xx.dtsi"
> >
> > / {
> > ...
> >     cpus {
> >         cpu@0 {
> >             cpu0-supply = <&dcdc2_reg>;
> >             operating-points = <
> >                 /* kHz    uV */
> >                 800000  1300000
> >                 600000  1112000
> >                 300000   969000
> >             >;
> >         };
> >     };
> >
> >     memory {
> >         device_type = "memory";
> >         reg = <0x80000000 0x08000000>; /* 128 Mib */
> >     };
> > ...
> >
> >     leds {
> >         pinctrl-names = "default";
> >         pinctrl-0 = <&user_leds_s0>;
> >
> >         compatible = "gpio-leds";
> >
> > ...
> >         led2 {
> >             label = "2a_service_yellow";
> >             gpios = <&gpio1 2 GPIO_ACTIVE_HIGH>;
> >             linux,default-trigger = "2a_service_yellow";
> >             default-state = "off";
> >         };
> >
> > ...
> >     };
> > ...
> > };
> >
> > &am33xx_pinmux {
> >     pinctrl-names = "default";
> >     pinctrl-0 = <&gpio_misc_pins>;
> >
> > ...
> >     user_leds_s0: user_leds_s0 {
> >         pinctrl-single,pins = <
> > ...
> >             0x24 (PIN_OUTPUT_PULLDOWN | MUX_MODE7) /* (T10)
> > gpmc_ad9.gpio0[23] */
> >         >;
> >     };
> > ...
> > };
> > ...
> >
> > Kind regards
> > Daniel
> > --
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