Re: kmemleak reports in kernel 3.9.5+

From: Ben Greear
Date: Mon Jun 17 2013 - 18:45:50 EST

On 06/13/2013 08:50 AM, Catalin Marinas wrote:
On Wed, Jun 12, 2013 at 01:28:13AM +0100, Ben Greear wrote:
On 06/11/2013 12:52 PM, Ben Greear wrote:
On 06/10/2013 03:32 PM, Catalin Marinas wrote:
On 10 June 2013 19:22, Ben Greear <greearb@xxxxxxxxxxxxxxx> wrote:
We had a system go OOM while doing lots of wireless
stations. (System had 8GB of RAM, so I suspect a leak).

I enabled kmemleak in a 3.9.5 (plus some local patches) and
I see the entries below. Any idea if these are real or not?

Most of this went away when I disabled SLUB debugging and other
kernel hacking options. The wifi cfg80211_inform_bss_frame
remains, however. I'll go dig some more on that tomorrow...didn't
see anything obvious at first glance.

But, perhaps there could be some improvements to
kmemleak to make it deal better with the various kernel
debugging features?

That's unrelated to the debugging features. Kmemleak cannot find
pointers to the allocated objects. They could be real leaks or it simply
doesn't scan the right memory where such pointers are stored. The debug
objects are stored in a list with the head as static memory, so it
should be scanned.

I re-ran a similar test just now, but I had added an explicit reference
for each of the items that I know this test causes to leak (I add them
to a global list.)

This means that memleak would no longer show them as leaked, and that
also cleaned up all of the strange leaks reported before.

So, I think kmemleak is at least mostly working properly, even with lots
of debugging options.


Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc

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