kernel BUG at /usr/src/packages/BUILD/kernel-default-3.0.101/linux-3.0/fs/nfs/nfs4xdr.c:856!

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Environment

SUSE Linux Enterprise Server 11 Service Pack 3 (SLES 11 SP3)

Situation

Only on systems using NFSv4.1.

After updating to kernel 3.0.101-0.35 the system starts panicking with:

------------[ cut here ]------------
kernel BUG at /usr/src/packages/BUILD/kernel-default-3.0.101/linux-3.0/fs/nfs/nfs4xdr.c:856!
[...]

PID: 28     TASK: ffff8800378fa600  CPU: 0   COMMAND: "kworker/0:2"
 #0 [ffff880037ad7a50] machine_kexec at ffffffff8102c0ae
 #1 [ffff880037ad7aa0] crash_kexec at ffffffff810ac11a
 #2 [ffff880037ad7b70] oops_end at ffffffff814637b8
 #3 [ffff880037ad7b90] do_invalid_op at ffffffff81003624
 #4 [ffff880037ad7c30] invalid_op at ffffffff8146afdb
    [exception RIP: encode_nops+17]
    RIP: ffffffffa0498031  RSP: ffff880037ad7ce8  RFLAGS: 00010202
    RAX: ffff88003cf89154  RBX: ffff880037ad7d40  RCX: ffff88003cf89154
    RDX: 0000000000000009  RSI: 0000000000000010  RDI: ffff880037ad7cf0
    RBP: ffff8800234c0008   R8: 64646e69665f746d   R9: 0000000000000001
    R10: ffff88003cf89131  R11: 676f6c2e6574656c  R12: ffff88003ae28320
    R13: ffff88003cf89070  R14: ffff8800234c0008  R15: ffffffffa049e2b0
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #5 [ffff880037ad7ce8] nfs4_xdr_enc_open at ffffffffa049e39c [nfs]
 #6 [ffff880037ad7d38] rpcauth_wrap_req at ffffffffa03eb17c [sunrpc]
 #7 [ffff880037ad7db8] rpc_xdr_encode at ffffffffa03e1011 [sunrpc]
 #8 [ffff880037ad7dd8] call_transmit at ffffffffa03e11b8 [sunrpc]
 #9 [ffff880037ad7de8] __rpc_execute at ffffffffa03ea2b5 [sunrpc]
#10 [ffff880037ad7e18] rpc_async_schedule at ffffffffa03ea4ad [sunrpc]
#11 [ffff880037ad7e28] process_one_work at ffffffff8107ba0c
#12 [ffff880037ad7e78] worker_thread at ffffffff8107e63a
#13 [ffff880037ad7ee8] kthread at ffffffff810829a6
#14 [ffff880037ad7f48] kernel_thread_helper at ffffffff8146b164
[...]

In doubt what NFS version is being used or available:

If "cat /proc/fs/nfsd/versions"
shows
"+2 +3 +4 +4.1"
NFSv4.1 was enabled and is likely being used.

Resolution

The kernel update released end of October, kernel 3.0.101-0.40.1 includes the patch to resolve the problem.

Cause

A recent change to the 'OPEN' compound in NFSv4 added an 'ACCESS' request to the 'OPEN' compound. This change now needs 9 OPS per request and NFS4_MAX_OPS needed to be adjusted.

Additional Information

Disclaimer

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