From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [bisected] xfrm: TCP connection initiating PMTU discovery
 stalls on v3.
Date: Fri, 12 Dec 2014 14:31:49 -0800
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Cc: Wolfgang Walter <linux@stwm.de>, netdev@vger.kernel.org,
	Eric Dumazet <edumazet@google.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Steffen Klassert <steffen.klassert@secunet.com>
To: Thomas Jarosch <thomas.jarosch@intra2net.com>
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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.

Disabling TX checksum automatically disables GSO.

Disabling TSO/GSO is the real 'cure' for the time being, you can keep TX
checksums.