Fwd: TCP fragmentation broken in 3.6-rc ?

Hi,

It seems somehow something was broken in 3.6-rc.
I'm not sure exactly what though. The symptoms are:

 - TCP connection get "stuck" with data in send queue when doing
"large" transfers ( like typing 'ps ax' on a ssh connection )
 - Only happens on path where the PMTU is lower than the MTU of the interface
 - Is not present right after boot, it only appears 10-20min after
boot or so. (and that's inside the _same_ TCP connection, it works
fine at first and then in the same ssh session, it'll get stuck)
 - Definitely seems related to fragments somehow since I see a router
sending ICMP message saying fragmentation is needed.
 - Exact same setup works fine with kernel 3.5.1

Cheers,

    Sylvain