From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Gorsulowski Subject: Re: [ISSUE] Memleak in LED sysfs on heavy usage Date: Mon, 19 Sep 2016 06:35:30 +0200 Message-ID: References: <37b949b3-6a9a-b8e3-c164-5ac2d44c9b3c@samsung.com> <7bb9a00e-0927-2fdc-5733-64bf922ebed6@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mxu02.htp-tel.de ([81.14.242.9]:38154 "EHLO mxuout02.htp-tel.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750786AbcISEfr (ORCPT ); Mon, 19 Sep 2016 00:35:47 -0400 In-Reply-To: <7bb9a00e-0927-2fdc-5733-64bf922ebed6@samsung.com> Sender: linux-leds-owner@vger.kernel.org List-Id: linux-leds@vger.kernel.org To: Jacek Anaszewski , "linux-leds@vger.kernel.org" Cc: "linux-kernel@vger.kernel.org" , Greg KH Hi Jacek, Am 16.09.2016 um 15:41 schrieb Jacek Anaszewski: > On 09/16/2016 02:08 PM, Daniel Gorsulowski wrote: >> Hi Jacek, >> >> Am 16.09.2016 um 13:25 schrieb Jacek Anaszewski: >>> On 09/16/2016 10:15 AM, Daniel Gorsulowski wrote: >>>> 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 >>>> >>> >>> Unfortunately I am still unable to reproduce the problem with leds-gpio. >>> I'm not observing any heavy usage with your test case: >>> >>> ~#free >>> total used free shared buffers >>> cached >>> Mem: 1028092 61364 966728 0 8416 22396 >>> -/+ buffers/cache: 30552 997540 >>> Swap: 0 0 0 >>> >>> >>> Actually you didn't give any numbers. What kernel version are you using? >>> >> As I wrote, the problems occurred in vanilla 4.6 kernel, but also in 4.4 >> kernel (with PREEMPT-RT Patchset). > > Heh, funny coincidence. I was testing this on recent linux-leds.git, > for-next branch and was not able to detect the issue. It started to > appear after resetting HEAD to 4.8-rc2 base. Finally it turned out > that what fixes the issue is the most recent commit [1]. > > Further investigation revealed that this is kobject_uevent_env(), > called from led_trigger_set(), which causes memory leaks when called > with high frequency. > > CC GregKH. > > [1] > https://git.kernel.org/cgit/linux/kernel/git/j.anaszewski/linux-leds.git/commit/?h=for-next&id=f3f624941be0fafb29fff5c1411fa433feca792c > Nice to hear about the Fix, thanks for your investigation! Kind regards, Daniel