> On Sep 24, 2023, at 9:07 AM, Mantas Mikulėnas <grawity@xxxxxxxxx> wrote: > > I've recently upgraded my home NFS server from 6.4.12 to 6.5.4 (running Arch Linux x86_64). > > Now, when I'm accessing the server over NFSv4.2 from a client that's running 5.10.0 (32-bit x86, Debian 11), if the mount is using sec=krb5i or sec=krb5p, trying to read a file that's <= 4092 bytes in size will return all-zero data. (That is, `hexdump -C file` shows "00 00 00...") Files that are 4093 bytes or larger seem to be unaffected. > > Only sec=krb5i/krb5p are affected by this – plain sec=krb5 (or sec=sys for that matter) seems to work without any problems. > > Newer clients (like 6.1.x or 6.4.x) don't seem to have any issues, it's only 5.10.0 that does... though it might also be that the client is 32-bit, but the same client did work previously when the server was running older kernels, so I still suspect 6.5.x on the server being the problem. > > Upgrading to 6.6.0-rc2 on the server hasn't changed anything. > The server is using Btrfs but I've tested with tmpfs as well. I'm guessing proto=tcp as well (as opposed to proto=rdma). Does the problem go away with vers=4.1 ? Can you capture network traffic during the failure? Use sec=krb5i so we can see the RPC payloads. On the client: # tcpdump -iany -s0 -w/tmp/sniffer.pcap -- Chuck Lever
