Re: memory leak in 2.6.11-rc2

[Andrea Arcangeli <andrea@suse.de>]

On Mon, Jan 24, 2005 at 10:45:47PM -0500, Dave Jones wrote:
> On Tue, Jan 25, 2005 at 02:19:24PM +1100, Andrew Tridgell wrote:
>  > The problem I've hit now is a severe memory leak. I have applied the
>  > patch from Linus for the leak in free_pipe_info(), and still I'm
>  > leaking memory at the rate of about 100Mbyte/minute.
>  > I've tested with both 2.6.11-rc2 and with 2.6.11-rc1-mm2, both with
>  > the pipe leak fix. The setup is:
> 
> That's a little more extreme than what I'm seeing, so it may be
> something else, but my firewall box needs rebooting every
> few days. It leaks around 50MB a day for some reason.
> Given it's not got a lot of ram, after 4-5 days or so, it's
> completely exhausted its swap too.
> 
> It's currently on a 2.6.10-ac kernel, so it's entirely possible that
> we're not looking at the same issue, though it could be something
> thats been there for a while if your workload makes it appear
> quicker than a firewall/ipsec gateway would.
> Do you see the same leaks with an earlier kernel ?
> 
> post OOM (when there was about 2K free after named got oom-killed)
> this is what slabinfo looked like..
> 
> dentry_cache        1502   3775    160   25    1 : tunables  120   60    0 : slabdata    151    151      0
> vm_area_struct      1599   2021     84   47    1 : tunables  120   60    0 : slabdata     43     43      0
> size-128            3431   6262    128   31    1 : tunables  120   60    0 : slabdata    202    202      0
> size-64             4352   4575     64   61    1 : tunables  120   60    0 : slabdata     75     75      0
> avtab_node          7073   7140     32  119    1 : tunables  120   60    0 : slabdata     60     60      0
> size-32             7256   7616     32  119    1 : tunables  120   60    0 : slabdata     64     64      0

What is avtab_node? there's no such thing in my kernel. But the above
can be ok. Can you show meminfo too after oom kill?

Just another datapoint my firewall runs a kernel based on 2.6.11-rc1-bk8 with
all the needed oom fixes and I've no problems on it yet. I run it oom
and this is what I get after the oom:

athlon:/home/andrea # free
             total       used       free     shared    buffers     cached
Mem:        511136      50852     460284          0        572      15764
-/+ buffers/cache:      34516     476620
Swap:      1052248          0    1052248
athlon:/home/andrea # 

The above is sane, 34M is very reasonable for what's loaded there
(there's the X server running, named too, and various other non standard
daemons, one even has a virtual size of >100m so it's not a tiny thing),
so I'm quite sure I'm not hitting a memleak, at least not on the
firewal. No ipsec on it btw, and it's a pure IDE without anything
special, just quite a few nics and USB usermode running all the time.

athlon:/home/andrea # uptime
  1:34pm  up 2 days 12:08,  1 user,  load average: 0.98, 1.13, 0.54
athlon:/home/andrea # iptables -L -v |grep -A2 FORWARD
Chain FORWARD (policy ACCEPT 65 packets, 9264 bytes)
 pkts bytes target     prot opt in     out     source               destination         
3690K 2321M block      all  --  any    any     anywhere             anywhere            
athlon:/home/andrea # 

So if there's a memleak in rc1-bk8, it's probably not in the core of the
kernel, but in some driver or things like ipsec. Either that or it broke
after 2.6.11-rc1-bk8. The kernel I'm running is quite heavily patched
too, but I'm not aware of any memleak fix in the additional patches.

Anyway I'll try again in a few days to verify it goes back down again to
exactly 34M of anonymous/random and 15M of cache.

No apparent problem on my desktop system either, it's running the same
kernel with different config.

If somebody could fix the kernel CVS I could have a look at the
interesting changesets between 2.6.11-rc1-bk8 and 2.6.11-rc2.