From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacek Anaszewski Subject: Re: [ISSUE] Memleak in LED sysfs on heavy usage Date: Fri, 16 Sep 2016 15:41:09 +0200 Message-ID: <7bb9a00e-0927-2fdc-5733-64bf922ebed6@samsung.com> References: <37b949b3-6a9a-b8e3-c164-5ac2d44c9b3c@samsung.com> <4d51014d-c8fa-4687-cae8-1a8dd0f79beb@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:56571 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755809AbcIPNlQ (ORCPT ); Fri, 16 Sep 2016 09:41:16 -0400 In-reply-to: Sender: linux-leds-owner@vger.kernel.org List-Id: linux-leds@vger.kernel.org To: Daniel Gorsulowski , "linux-leds@vger.kernel.org" Cc: "linux-kernel@vger.kernel.org" , Greg KH 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 -- Best regards, Jacek Anaszewski