From: Greg KH <greg@kroah.com>
To: Jacek Anaszewski <j.anaszewski@samsung.com>
Cc: Daniel Gorsulowski <daniel.gorsulowski@esd.eu>,
"linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [ISSUE] Memleak in LED sysfs on heavy usage
Date: Fri, 16 Sep 2016 16:39:51 +0200 [thread overview]
Message-ID: <20160916143951.GA20908@kroah.com> (raw)
In-Reply-To: <aa2f963b-0d48-6746-4795-0033994814cd@samsung.com>
On Fri, Sep 16, 2016 at 04:32:39PM +0200, Jacek Anaszewski wrote:
> On 09/16/2016 04:06 PM, Greg KH wrote:
> > On Fri, Sep 16, 2016 at 03:41:09PM +0200, Jacek Anaszewski wrote:
> > > 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.
> >
> > Really? Where in kobject_uevent_env() is the memory leak?
>
> I'll chase it down when and will let you know. This may be
> non-trivial issue as it suffices to add "sleep 0.1" between
> brightness setting operations to prevent it.
Why are you abusing uevents for flashing an LED? Please don't do that,
it's not what that interface is for at all.
greg k-h
next prev parent reply other threads:[~2016-09-16 14:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20160912085832eucas1p1e7332f761e5e0cb764a6831b9a519b70@eucas1p1.samsung.com>
2016-09-12 8:50 ` [ISSUE] Memleak in LED sysfs on heavy usage Daniel Gorsulowski
2016-09-13 7:16 ` Jacek Anaszewski
2016-09-16 7:31 ` Jacek Anaszewski
2016-09-16 8:15 ` Daniel Gorsulowski
2016-09-16 11:25 ` Jacek Anaszewski
2016-09-16 12:08 ` Daniel Gorsulowski
2016-09-16 13:41 ` Jacek Anaszewski
2016-09-16 14:06 ` Greg KH
2016-09-16 14:32 ` Jacek Anaszewski
2016-09-16 14:39 ` Greg KH [this message]
2016-09-16 18:49 ` Jacek Anaszewski
2016-09-16 19:44 ` Greg KH
2016-09-16 21:08 ` Jacek Anaszewski
2016-09-19 8:35 ` Jacek Anaszewski
2016-09-19 4:35 ` Daniel Gorsulowski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160916143951.GA20908@kroah.com \
--to=greg@kroah.com \
--cc=daniel.gorsulowski@esd.eu \
--cc=j.anaszewski@samsung.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-leds@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).