linux-kernel - Re: tracking memory usage/leak in "inactive" field in /proc/meminfo?

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Date:	Thu, 11 Feb 2010 09:45:42 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Chris Friesen <cfriesen@...tel.com>
Cc:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Rik van Riel <riel@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-mm@...ck.org, Balbir Singh <balbir@...ux.vnet.ibm.com>
Subject: Re: tracking memory usage/leak in "inactive" field in /proc/meminfo?

Hi, Chris.

On Thu, Feb 11, 2010 at 2:05 AM, Chris Friesen <cfriesen@...tel.com> wrote:
> On 02/09/2010 06:32 PM, KOSAKI Motohiro wrote:
>
>> can you please post your /proc/meminfo?
>
>
> On 02/09/2010 09:50 PM, Balbir Singh wrote:
>> Do you have swap enabled? Can you help with the OOM killed dmesg log?
>> Does the situation get better after OOM killing.
>
>
> On 02/09/2010 10:09 PM, KOSAKI Motohiro wrote:
>
>> Chris, 2.6.27 is a bit old. plese test it on latest kernel. and please
> don't use
>> any proprietary drivers.
>
>
> Thanks for the replies.
>
> Swap is enabled in the kernel, but there is no swap configured.  ipcs
> shows little consumption there.
>
> The test load relies on a number of kernel modifications, making it
> difficult to use newer kernels. (This is an embedded system.)  There are
> no closed-source drivers loaded, though there are some that are not in
> vanilla kernels.  I haven't yet tried to reproduce the problem with a
> minimal load--I've been more focused on trying to understand what's
> going on in the code first.  It's on my list to try though.
>
> Here are some /proc/meminfo outputs from a test run where we
> artificially chewed most of the free memory to try and force the oom
> killer to fire sooner (otherwise it takes days for the problem to trigger).
>
> It's spaced with tabs so I'm not sure if it'll stay aligned.  The first
> row is the sample number.  All the HugePages entries were 0.  The
> DirectMap entries were constant. SwapTotal/SwapFree/SwapCached were 0,
> as were Writeback/NFS_Unstable/Bounce/WritebackTmp.
>
> Samples were taken 10 minutes apart.  Between samples 49 and 50 the
> oom-killer fired.
>
>                13              49              50
> MemTotal        4042848         4042848         4042848
> MemFree         113512          52668           69536
> Buffers         20              24              76
> Cached          1285588         1287456         1295128
> Active          2883224         3369440         2850172
> Inactive        913756          487944          990152
> Dirty           36              216             252
> AnonPages       2274756         2305448         2279216
> Mapped          10804           12772           15760
> Slab            62324           62568           63608
> SReclaimable    24092           23912           24848
> SUnreclaim      38232           38656           38760
> PageTables      11960           12144           11848
> CommitLimit     2021424         2021424         2021424
> Committed_AS    12666508        12745200        7700484
> VmallocUsed     23256           23256           23256
>
> It's hard to get a good picture from just a few samples, so I've
> attached an ooffice spreadsheet showing three separate runs.  The
> samples above are from sheet 3 in the document.
>
> In those spreadsheets I notice that
> memfree+active+inactive+slab+pagetables is basically a constant.
> However, if I don't use active+inactive then I can't make the numbers
> add up.  And the difference between active+inactive and
> buffers+cached+anonpages+dirty+mapped+pagetables+vmallocused grows
> almost monotonically.

Such comparison is not right. That's because code pages of program account
with cached and mapped but they account just one in lru list(active +
inactive).
Also, if you use mmap on any file, above is applied.

I can't find any clue with your attachment.
You said you used kernel with some modification and non-vanilla drivers.
So I suspect that. Maybe kernel memory leak?

Now kernel don't account kernel memory allocations except SLAB.
I think this patch can help you find the kernel memory leak.
(It isn't merged with mainline by somewhy but it is useful to you :)

http://marc.info/?l=linux-mm&m=123782029809850&w=2


>
> Thanks,
>
> Chris
>



-- 
Kind regards,
Minchan Kim
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