> I think we are still not understanding what network setup that is > happening that leads to a client sending a SYN (which is incorrect) to > what is supposed to be an unreachable server instead of timing out > fast (because there shouldn't be an ARP entry). > > Mike, can you show your arp cache info (arp -n) during your run? Here's my run: (Note: 10.162.159.253 is the gateway for the default route.) root@mikes-ubuntu-21-04:/tmp/dbg# date; arp -n; date; cat mount_hang.sh; date; ./mount_hang.sh; date; arp -n Wed Jun 9 17:00:07 UTC 2021 Address HWtype HWaddress Flags Mask Iface 10.162.159.253 ether 00:00:0c:9f:fa:3c C ens192 Wed Jun 9 17:00:07 UTC 2021 #!/bin/sh -x mount -o vers=4 -v -v -v 2.2.2.2:/fake_path /tmp/mnt.dead & echo PID_OF_DEAD_BG_MOUNT=$! sleep 5 mount -o vers=4 -v -v -v 10.188.76.67:/git /tmp/mnt.alive Wed Jun 9 17:00:07 UTC 2021 + echo+ mount -o vers=4 -v -v -v 2.2.2.2:/fake_path /tmp/mnt.dead PID_OF_DEAD_BG_MOUNT=767703 PID_OF_DEAD_BG_MOUNT=767703 + sleep 5 mount.nfs: timeout set for Wed Jun 9 17:02:07 2021 mount.nfs: trying text-based options 'vers=4,addr=2.2.2.2,clientaddr=10.162.132.231' + mount -o vers=4 -v -v -v 10.188.76.67:/git /tmp/mnt.alive mount.nfs: timeout set for Wed Jun 9 17:02:12 2021 mount.nfs: trying text-based options 'vers=4,addr=10.188.76.67,clientaddr=10.162.132.231' mount.nfs: mount(2): Connection timed out mount.nfs: Connection timed out mount.nfs: mount(2): Connection timed out mount.nfs: Connection timed out mount.nfs: mount(2): Connection timed out mount.nfs: Connection timed out Wed Jun 9 17:07:40 UTC 2021 Address HWtype HWaddress Flags Mask Iface 10.162.159.253 ether 00:00:0c:9f:fa:3c C ens192 10.162.159.252 ether 00:de:fb:a6:56:7c C ens192 root@mikes-ubuntu-21-04:/tmp/dbg#
