From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?B?S3J6eXN6dG9mIE9sxJlkemtp?= Subject: Re: 2.6.34: Problem with UDP traffic on lo + poll(?) Date: Tue, 07 Sep 2010 23:51:02 +0200 Message-ID: <4C86B3C6.7040809@ans.pl> References: <1283802132.2585.4.camel@edumazet-laptop> <4C854737.5040503@ans.pl> <1283804955.2585.12.camel@edumazet-laptop> <4C8552B1.8020806@ans.pl> <4C855385.7030203@ans.pl> <4C865C21.5010803@ans.pl> <1283877391.2313.62.camel@edumazet-laptop> <1283887569.2634.95.camel@edumazet-laptop> <4C86AE96.40704@ans.pl> <1283895544.2634.256.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: David Miller , netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from bizon.gios.gov.pl ([195.187.34.71]:59519 "EHLO bizon.gios.gov.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751056Ab0IGVvJ (ORCPT ); Tue, 7 Sep 2010 17:51:09 -0400 In-Reply-To: <1283895544.2634.256.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: On 2010-09-07 23:39, Eric Dumazet wrote: > Le mardi 07 septembre 2010 =C3=A0 23:28 +0200, Krzysztof Ol=C4=99dzki= a =C3=A9crit : >=20 >> With the above patch I'm no longer able to reproduce the problem. Th= anks! >> >> Tested-by: Krzysztof Piotr Oledzki >> >=20 > Thanks a lot ! >=20 >> BTW: why it takes so long to trigger this bug and it is only possibl= e >> over a loopback interface? >=20 > Its a bit tricky : You need at least 10 sockets linked in a particula= r > hash chain. >=20 > To check this, you can : >=20 > cat /proc/net/udp >=20 > maybe you have many sockets on port 123 or 53 ? On one affected host I have 3+7 and on the other, also affacted one, I = have 3+6: root@sowa:~# egrep -cw '(53|123):' /proc/net/udp 10 root@sowa:~# egrep -w '(53|123):' /proc/net/udp 53: 3582A8C0:0035 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 6084654 2 ffff8800cc012700 0 53: 0100007F:0035 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 6084652 2 ffff8800cc010900 0 123: D683A8C0:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4911 2 ffff88012de96400 0 123: 7B85A8C0:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4910 2 ffff88012de96100 0 123: 8982A8C0:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4909 2 ffff88012de95e00 0 123: 7B82A8C0:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4908 2 ffff88012de95b00 0 123: 3582A8C0:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4907 2 ffff88012de95800 0 123: 1F7EA8C0:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4906 2 ffff88012de95500 0 123: 0100007F:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4905 2 ffff88012de95200 0 123: 00000000:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4899 2 ffff88012de94c00 0 root@cmyk:~# egrep -cw '(53|123):' /proc/net/udp 9 root@cmyk:~# egrep -w '(53|123):' /proc/net/udp 53: A2CD1253:0035 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 3774 2 eeaa9840 0 53: 0100A8C0:0035 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 3772 2 eeaa9a40 0 53: 0100007F:0035 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 3770 2 eeaa9c40 0 123: A6CD1253:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4693 2 eeacdc80 0 123: A5CD1253:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4692 2 eeaa9640 0 123: A2CD1253:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4691 2 ed201700 0 123: 0100A8C0:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4690 2 eeacd880 0 123: 0100007F:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4689 2 ec649740 0 123: 00000000:007B 00000000:0000 07 00000000:00000000 00:00000000 000= 00000 0 0 4683 2 ed201d00 0 But how 123 is related to 53? > And about loopback, I have no idea... I am pretty sure I can trigger = the > bug with other interfaces. OK. Probably it is because my other hosts have only a single IP and onl= y the problematic ones have both DNS server and multiple IP (many sockets= ). Best regards, Krzysztof Ol=C4=99dzki