On Fri, Dec 22, 2017 at 11:58:08AM +0100, Dmitry Vyukov wrote: ... > > Same with this one, perhaps related to / fixed by: > > http://patchwork.ozlabs.org/patch/850957/ > > > > > > Looking at the log, this one seems to be an infinite loop in SCTP code > with console output in it. Kernel is busy printing gazilion of: > > [ 176.491099] sctp: sctp_transport_update_pmtu: Reported pmtu 508 too > low, using default minimum of 512 > ** 110 printk messages dropped ** > [ 176.503409] sctp: sctp_transport_update_pmtu: Reported pmtu 508 too > low, using default minimum of 512 > ** 103 printk messages dropped ** > ... > [ 246.742374] sctp: sctp_transport_update_pmtu: Reported pmtu 508 too > low, using default minimum of 512 > [ 246.742484] sctp: sctp_transport_update_pmtu: Reported pmtu 508 too > low, using default minimum of 512 > [ 246.742590] sctp: sctp_transport_update_pmtu: Reported pmtu 508 too > low, using default minimum of 512 > > Looks like a different issue. >
Oh. I guess this is caused by the interface having a MTU smaller than SCTP_DEFAULT_MINSEGMENT (512), as the icmp frag needed handler (sctp_icmp_frag_needed) will trigger an instant retransmission. But as the MTU is smaller, SCTP won't update it, but will issue the retransmission anyway. I will test this soon. Should be fairly easy to trigger it. Marcelo
