Re: [gentoo-amd64] Hanging after a few days - 2.6.15-r7

[Brett Johnson]

On Mon, Mar 13, 2006 at 03:01:15PM +0800, P.V.Anthony wrote:
>
> With kernel 2.6.14 it works fine.
>
> Starting from 2.6.15 upto 2.6.15-r7, it will hang after a few days.
>
I have noticed a similar problem that appears to be a kind of memory
leak. I had upgraded both my desktop (amd64) and laptop (x86) from
2.6.14 to 2.6.15 a few weeks ago. After the upgrade, I started noticing
that first thing in the morning or after long periods of the system being
idle, the memory usage would climb to around 550MB. This seemed odd, as
my normal memory usage is around 120MB (using conky as my system monitor).

I tried to identify what process was consuming all that ram, but nothing
looked out of the ordinary. As I started wokring on the machine, the
memory usage would slowly go down over the course of a few hours, and
level off around 200MB (which is still more than normal).

I have noticed this behavior on both my AMD64 box and my x86 laptop,
using 2.6.15 from both ck-sources and gentoo-sources. I did read the
release notes in gentoo-sources and over the life of 2.6.15 there have
been a couple memory leak fixes introduced (one for the mouse dev and one
for SCSI). Neither of these fixes seemed to make a difference (I first
noticed the issue with 2.6.15-r1, then 2.6.15-r5 and still in 2.6.15-r7).

Some of the steps I took to identify the root cause were to close all
applications, shutdown X, stop all non essitinal services and checking
the memory usage after each change. I did see small drops in memory, but
even with everything shutdown, the system would still be consuming 350MB+
of ram. And again, after starting everything back up, I would still see
375MB+ or ram usage, but as I used the system it would tail off to around
200MB.

I'm not sure this is a true memory leak, as most of the memory is
reclaimed after a period of system usage. Most memory leaks I have run
across just consume ram until there is nothing left and the system hangs,
which sounds similar to what you are seeing.

You did not specify what types of errors, dmesg output or anything else
about your crash, so it could likely be something completely different.
I was planning on posting about my expirence with 2.6.15 anyways, and
your issue at a very high level sounded like it might be related. Maybe
you could check your ram usage after the system has been up (and
possibly idle) for a long time (I have seen the memory climb after
about 8 hours or so of being idle).

This weekend I went back to 2.6.14 on both systems, and I have not seen the
strange memory usage issue yet.

I am not sure how to go about isolating this issue any further to be able
to file a proper bug report. I don't think I have enough information at this
time, and I can't seem to find any method of identifying what is using the
large chunks of ram when idle, and then freeing as the system is used.

Regards,
Brett
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