> On Jun 13, 2024, at 6:44 PM, Chris Friesen <cbf123@xxxxxxxx> wrote: > > Hi all, > > I'm not subscribed to the list so please CC me on replies. I'm seeing some odd behaviour and I'm not sure what's going on. > > The short version is that I can mount NFS exports from this server (including mounting on the server itself) via TCP but not via UDP. > > rpcinfo on the server gives the following: > > root@controller-0:/var/home/sysadmin# rpcinfo -s > program version(s) netid(s) service owner > 100000 2,3,4 local,udp,tcp,udp6,tcp6 portmapper superuser > 100024 1 tcp6,udp6,tcp,udp status 116 > 100003 4,3 udp6,tcp6,udp,tcp nfs superuser > 100227 3 udp6,tcp6,udp,tcp - superuser > 100021 4,3,1 tcp6,udp6,tcp,udp nlockmgr superuser > 100005 3,2,1 tcp6,udp6,tcp,udp mountd superuser > > root@controller-0:/var/home/sysadmin# rpcinfo -p > program vers proto port service > 100000 4 tcp 111 portmapper > 100000 3 tcp 111 portmapper > 100000 2 tcp 111 portmapper > 100000 4 udp 111 portmapper > 100000 3 udp 111 portmapper > 100000 2 udp 111 portmapper > 100024 1 udp 44993 status > 100024 1 tcp 60561 status > 100003 3 tcp 2049 nfs > 100003 4 tcp 2049 nfs > 100227 3 tcp 2049 > 100003 3 udp 2049 nfs > 100227 3 udp 2049 > 100021 1 udp 36993 nlockmgr > 100021 3 udp 36993 nlockmgr > 100021 4 udp 36993 nlockmgr > 100021 1 tcp 33239 nlockmgr > 100021 3 tcp 33239 nlockmgr > 100021 4 tcp 33239 nlockmgr > 100005 1 udp 43636 mountd > 100005 1 tcp 49357 mountd > 100005 2 udp 39783 mountd > 100005 2 tcp 54527 mountd > 100005 3 udp 40970 mountd > 100005 3 tcp 41761 mountd > > > So it *looks* okay to me, but if I probe it I get the expected response for TCP but not for UDP: > > root@controller-0:/var/home/sysadmin# rpcinfo -T tcp localhost 100003 4 > program 100003 version 4 ready and waiting > root@controller-0:/var/home/sysadmin# rpcinfo -T tcp localhost 100003 3 > program 100003 version 3 ready and waiting > root@controller-0:/var/home/sysadmin# rpcinfo -T udp localhost 100003 3 > rpcinfo: RPC: Timed out > program 100003 version 3 is not available > > > Oddly the last command returns immediately so it's not actually timing out, the error message is a bit misleading. If I sniff the network traffic while running that last command, I see this: > > root@controller-0:/var/home/sysadmin# tcpdump -vvv -i lo port 2049 > tcpdump: listening on lo, link-type EN10MB (Ethernet), snapshot length 262144 bytes > 20:20:53.159743 IP (tos 0x0, ttl 64, id 58251, offset 0, flags [DF], proto UDP (17), length 68) > localhost.887 > localhost.nfs: NFS request xid 1717614110 40 null > 20:20:53.160016 IP (tos 0x0, ttl 64, id 58252, offset 0, flags [DF], proto UDP (17), length 28) > localhost.nfs > localhost.887: [bad udp cksum 0xfe1b -> 0xf663!] UDP, length 0 > > > Ignoring the checksums, I get this: > > root@controller-0:/var/home/sysadmin# tcpdump -vvv -K -i lo port 2049 > tcpdump: listening on lo, link-type EN10MB (Ethernet), snapshot length 262144 bytes > 20:21:49.642588 IP (tos 0x0, ttl 64, id 22026, offset 0, flags [DF], proto UDP (17), length 68) > localhost.934 > localhost.nfs: NFS request xid 1718297876 40 null > 20:21:49.642697 IP (tos 0x0, ttl 64, id 22027, offset 0, flags [DF], proto UDP (17), length 28) > localhost.nfs > localhost.934: UDP, length 0 > > > On a separate system with a 5.10 kernel I get a successful response that is longer and is properly decoded: > > root@controller-0:/var/home/sysadmin# tcpdump -vvv -K -i lo port 2049 > tcpdump: listening on lo, link-type EN10MB (Ethernet), snapshot length 262144 bytes > 22:22:00.388497 IP (tos 0x0, ttl 64, id 806, offset 0, flags [DF], proto UDP (17), length 68) > localhost.808 > localhost.nfs: NFS request xid 1718037578 40 null > 22:22:00.388525 IP (tos 0x0, ttl 64, id 807, offset 0, flags [DF], proto UDP (17), length 52) > localhost.nfs > localhost.808: NFS reply xid 1718037578 reply ok 24 null > > > Anyone have any ideas what might be going on or how to debug? I'm building a kernel with CONFIG_SUNRPC_DEBUG enabled to see if that gives anything useful. linux-6.6.15 has "SUNRPC: use request size to initialize bio_vec in svc_udp_sendto()" which might address this issue. -- Chuck Lever
