From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Walter Subject: Re: [bisected] xfrm: TCP connection initiating PMTU discovery stalls on v3. Date: Sat, 13 Dec 2014 00:47:45 +0100 Message-ID: <1500356.bBOpW4o4zG@h2o.as.studentenwerk.mhn.de> References: <1709726.jUgUSQI9sl@pikkukde.a.i2n> <548B5E6E.6010208@intra2net.com> <1418423509.13491.26.camel@edumazet-glaptop2.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Thomas Jarosch , netdev@vger.kernel.org, Eric Dumazet , Herbert Xu , Steffen Klassert To: Eric Dumazet Return-path: Received: from dresden.studentenwerk.mhn.de ([141.84.225.229]:49194 "EHLO email.studentenwerk.mhn.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752782AbaLLXrs convert rfc822-to-8bit (ORCPT ); Fri, 12 Dec 2014 18:47:48 -0500 In-Reply-To: <1418423509.13491.26.camel@edumazet-glaptop2.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: Am Freitag, 12. Dezember 2014, 14:31:49 schrieben Sie: > On Fri, 2014-12-12 at 22:30 +0100, Thomas Jarosch wrote: > > if it's any help: Disabling TX checksumming prevents the hang > > even on an unpatched 3.14.x kernel. You could check with your debug > > statements in place the path of the packets with and without TX > > checksumming. I can't disable it as the driver will not allow it: # ethtool -K eth0 tx off Cannot change tx-checksumming Could not change any device features > Disabling TX checksum automatically disables GSO. >=20 > Disabling TSO/GSO is the real 'cure' for the time being, you can keep= TX > checksums. This does not help here. With GSO disabled (for network device serving = the=20 ipsec traffic, here e.g. eth0) the hang still occurs. tcp_set_skb_tso_s= egs()=20 gets called and the else-branch for skb->len <=3D mss_now is taken. I tested this serveral times. Regards, --=20 Wolfgang Walter Studentenwerk M=FCnchen Anstalt des =F6ffentlichen Rechts