Re: Memory leak in 2.6.11-rc1?

On Sun, Jan 23, 2005 at 02:32:48AM -0800, Andrew Morton wrote:

Jens Axboe [off-list ref] wrote:

quoted

But I'm still stuck with all of my ram gone after a
 600MB fillmem, half of it is just in swap.

Well.  Half of it has gone so far ;)

quoted

 Attaching meminfo and sysrq-m after fillmem.

(I meant a really big fillmem: a couple of 2GB ones.  Not to worry.)

It's not in slab and the pagecache and anonymous memory stuff seems to be
working OK.  So it has to be something else, which does a bare
__alloc_pages().  Low-level block stuff, networking, arch code, perhaps.

I don't think I've ever really seen code to diagnose this.

A simplistic approach would be to add eight or so ulongs into struct page,
populate them with builtin_return_address(0...7) at allocation time, then
modify sysrq-m to walk mem_map[] printing it all out for pages which have
page_count() > 0.  That'd find the culprit.

I think I may be seeing something odd here, maybe a possible memory leak.
The only problem I have is wondering whether I'm actually comparing like
with like.  Maybe some networking people can provide a hint?

Below is gathered from 2.6.11-rc1.

bash-2.05a# head -n2 /proc/slabinfo
slabinfo - version: 2.1
# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>
bash-2.05a# cat /proc/net/rt_cache | wc -l; grep ip_dst /proc/slabinfo
115
ip_dst_cache         759    885    256   15    1
bash-2.05a# cat /proc/net/rt_cache | wc -l; grep ip_dst /proc/slabinfo
117
ip_dst_cache         770    885    256   15    1
bash-2.05a# cat /proc/net/rt_cache | wc -l; grep ip_dst /proc/slabinfo
133
ip_dst_cache         775    885    256   15    1
bash-2.05a# cat /proc/net/rt_cache | wc -l; grep ip_dst /proc/slabinfo
18
ip_dst_cache         664    885    256   15    1
bash-2.05a# cat /proc/net/rt_cache | wc -l; grep ip_dst /proc/slabinfo
20
ip_dst_cache         664    885    256   15    1
bash-2.05a# cat /proc/net/rt_cache | wc -l; grep ip_dst /proc/slabinfo
22
ip_dst_cache         673    885    256   15    1
bash-2.05a# cat /proc/net/rt_cache | wc -l; grep ip_dst /proc/slabinfo
23
ip_dst_cache         670    885    256   15    1
bash-2.05a# cat /proc/net/rt_cache | wc -l; grep ip_dst /proc/slabinfo
24
ip_dst_cache         675    885    256   15    1
bash-2.05a# cat /proc/net/rt_cache | wc -l; grep ip_dst /proc/slabinfo
24
ip_dst_cache         669    885    256   15    1

I'm fairly positive when I rebooted the machine a couple of days ago,
ip_dst_cache was significantly smaller for the same number of lines in
/proc/net/rt_cache.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core