netdev - Re: After a while of system running no incoming UDP any more?

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Date:   Fri, 28 Jul 2017 01:41:05 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Paolo Abeni <pabeni@...hat.com>
Cc:     Marc Haber <mh+netdev@...schlus.de>, netdev@...r.kernel.org
Subject: Re: After a while of system running no incoming UDP any more?

On Fri, 2017-07-28 at 10:15 +0200, Paolo Abeni wrote:
> Hi,
> 
> On Fri, 2017-07-28 at 01:05 -0700, Eric Dumazet wrote:

> I think that the leaked sockets are still unhashed on close() (via
> udp_lib_close() -> sk_common_release() ->sk_proto->unhash()), so they
> should not be listed there ?!? (Rush answer, subject to lack of coffee
> issues)

If the daemon is still running, sockets are not closed and we can watch
refcount being increased.

We can see this even on an UDP_RR workload (no UDP flood at all)

lpk51:~# while :
> do
> ./super_netperf 10 -H 2002:af6:b34:: -t UDP_RR -l 1 -- -N
> done


lpk52:~# cat /proc/net/udp6|grep -v " 2 "
  sl  local_address                         remote_address
st tx_queue rx_queue tr tm->when retrnsmt   uid  timeout inode ref
pointer drops
  293: F60A02200000340B0000000000000000:F0A9
F60A02200000330B0000000000000000:AB11 01 00000000:00000000 00:00000000
00000000     0        0 583763 387 ffff880ddb862c00 0
 3251: F60A02200000340B0000000000000000:FC37
F60A02200000330B0000000000000000:EA7F 01 00000000:00000000 00:00000000
00000000     0        0 586126 356 ffff880dd25a7940 0
 4043: F60A02200000340B0000000000000000:FF4F
F60A02200000330B0000000000000000:9A35 01 00000500:00000000 00:00000000
00000000     0        0 583760 409 ffff880ddb863180 0
 7832: F60A02200000340B0000000000000000:8E1C
F60A02200000330B0000000000000000:DEC1 01 00000000:00000000 00:00000000
00000000     0        0 583766 387 ffff880ddb863700 0
 8568: F60A02200000340B0000000000000000:90FC
F60A02200000330B0000000000000000:8A60 01 00000000:00000000 00:00000000
00000000     0        0 580369 379 ffff880d9e7b2700 0
13085: F60A02200000340B0000000000000000:A2A1
F60A02200000330B0000000000000000:CDB3 01 00000000:00000000 00:00000000
00000000     0        0 586915 397 ffff880e31994140 0
14975: F60A02200000340B0000000000000000:AA03
F60A02200000330B0000000000000000:9C71 01 00000000:00000000 00:00000000
00000000     0        0 586123 355 ffff880d9d1baec0 0
15155: F60A02200000340B0000000000000000:AAB7
F60A02200000330B0000000000000000:D324 01 00000000:00000000 00:00000000
00000000     0        0 583769 367 ffff880dd88141c0 0
25421: F60A02200000340B0000000000000000:D2D1
F60A02200000330B0000000000000000:CA33 01 00000000:00000000 00:00000000
00000000     0        0 586120 424 ffff880dfda4b0c0 0
28774: F60A02200000340B0000000000000000:DFEA
F60A02200000330B0000000000000000:DD05 01 00000500:00000000 00:00000000
00000000     0        0 583757 411 ffff880ddb862680 0