Hello,

after upgrading from stable 6.1.63 to stable 6.6.3 our nfs-server logged 
a WARNING and then more and more clients hanged:


Dec 04 14:59:25 engel kernel: ------------[ cut here ]------------
Dec 04 14:59:25 engel kernel: WARNING: CPU: 17 PID: 8431 at 
fs/nfsd/nfs4state.c:4919 nfsd_break_deleg_cb+0x174/0x190 [nfsd]
Dec 04 14:59:25 engel kernel: Modules linked in: cts rpcsec_gss_krb5 msr 
8021q garp stp mrp llc binfmt_misc intel_rapl_msr intel_rapl_common 
sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp kv>
Dec 04 14:59:25 engel kernel:  enclosure sd_mod usbhid t10_pi hid 
crc64_rocksoft crc64 crc_t10dif crct10dif_generic ixgbe ahci xfrm_algo 
xhci_pci libahci dca mdio_devres mpt3sas ehci_pci crct10dif_p>
Dec 04 14:59:25 engel kernel: CPU: 17 PID: 8431 Comm: nfsd Not tainted 
6.6.3-debian64.all+1.2 #1
Dec 04 14:59:25 engel kernel: Hardware name: Supermicro X10DRi/X10DRI-T, 
BIOS 1.1a 10/16/2015
Dec 04 14:59:25 engel kernel: RIP: 0010:nfsd_break_deleg_cb+0x174/0x190 
[nfsd]
Dec 04 14:59:25 engel kernel: Code: 02 8c a4 c2 e9 ff fe ff ff 48 89 df 
be 01 00 00 00 e8 70 7c ed c2 48 8d bb 98 00 00 00 e8 b4 0e 01 00 84 c0 
0f 85 2e ff ff ff <0f> 0b e9 27 ff ff ff be 02 00 00 0>
Dec 04 14:59:25 engel kernel: RSP: 0018:ffffbd57227c7a98 EFLAGS: 
00010246
Dec 04 14:59:25 engel kernel: RAX: 0000000000000000 RBX: 
ffff94a77356e200 RCX: 0000000000000000
Dec 04 14:59:25 engel kernel: RDX: ffff94a77356e2c8 RSI: 
ffff94b78cf58000 RDI: 0000000000002000
Dec 04 14:59:25 engel kernel: RBP: ffff94a0392b3a34 R08: 
ffffbd57227c7a80 R09: 0000000000000000
Dec 04 14:59:25 engel kernel: R10: ffff94a05f4a9440 R11: 
0000000000000000 R12: ffff94b8e3995b00
Dec 04 14:59:25 engel kernel: R13: ffff94a0392b3a20 R14: 
ffff94b8e3995b00 R15: 000000010eb733cd
Dec 04 14:59:25 engel kernel: FS:  0000000000000000(0000) 
GS:ffff94b71fcc0000(0000) knlGS:0000000000000000
Dec 04 14:59:25 engel kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 
0000000080050033
Dec 04 14:59:25 engel kernel: CR2: 00007f9ef8554000 CR3: 
000000295e020003 CR4: 00000000001706e0
Dec 04 14:59:25 engel kernel: Call Trace:
Dec 04 14:59:25 engel kernel:  <TASK>
Dec 04 14:59:25 engel kernel:  ? nfsd_break_deleg_cb+0x174/0x190 [nfsd]
Dec 04 14:59:25 engel kernel:  ? __warn+0x81/0x130
Dec 04 14:59:25 engel kernel:  ? nfsd_break_deleg_cb+0x174/0x190 [nfsd]
Dec 04 14:59:25 engel kernel:  ? report_bug+0x171/0x1a0
Dec 04 14:59:25 engel kernel:  ? handle_bug+0x3c/0x80
Dec 04 14:59:25 engel kernel:  ? exc_invalid_op+0x17/0x70
Dec 04 14:59:25 engel kernel:  ? asm_exc_invalid_op+0x1a/0x20
Dec 04 14:59:25 engel kernel:  ? nfsd_break_deleg_cb+0x174/0x190 [nfsd]
Dec 04 14:59:25 engel kernel:  ? nfsd_break_deleg_cb+0x9a/0x190 [nfsd]
Dec 04 14:59:25 engel kernel:  __break_lease+0x25c/0x720
Dec 04 14:59:25 engel kernel:  __nfsd_open.isra.0+0xa9/0x1a0 [nfsd]
Dec 04 14:59:25 engel kernel:  nfsd_file_do_acquire+0x4ca/0xc50 [nfsd]
Dec 04 14:59:25 engel kernel:  nfs4_get_vfs_file+0x34c/0x3b0 [nfsd]
Dec 04 14:59:25 engel kernel:  nfsd4_process_open2+0x42c/0x15d0 [nfsd]
Dec 04 14:59:25 engel kernel:  ? nfsd_permission+0x63/0x100 [nfsd]
Dec 04 14:59:25 engel kernel:  ? fh_verify+0x42e/0x720 [nfsd]
Dec 04 14:59:25 engel kernel:  nfsd4_open+0x64a/0xc40 [nfsd]
Dec 04 14:59:25 engel kernel:  ? nfsd4_encode_operation+0xa7/0x2b0 
[nfsd]
Dec 04 14:59:25 engel kernel:  nfsd4_proc_compound+0x351/0x670 [nfsd]
Dec 04 14:59:25 engel kernel:  ? __pfx_nfsd+0x10/0x10 [nfsd]
Dec 04 14:59:25 engel kernel:  nfsd_dispatch+0x7c/0x1b0 [nfsd]
Dec 04 14:59:25 engel kernel:  svc_process_common+0x431/0x6e0 [sunrpc]
Dec 04 14:59:25 engel kernel:  ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
Dec 04 14:59:25 engel kernel:  ? __pfx_nfsd+0x10/0x10 [nfsd]
Dec 04 14:59:25 engel kernel:  svc_process+0x131/0x180 [sunrpc]
Dec 04 14:59:25 engel kernel:  nfsd+0x84/0xd0 [nfsd]
Dec 04 14:59:25 engel kernel:  kthread+0xe5/0x120
Dec 04 14:59:25 engel kernel:  ? __pfx_kthread+0x10/0x10
Dec 04 14:59:25 engel kernel:  ret_from_fork+0x31/0x50
Dec 04 14:59:25 engel kernel:  ? __pfx_kthread+0x10/0x10
Dec 04 14:59:25 engel kernel:  ret_from_fork_asm+0x1b/0x30
Dec 04 14:59:25 engel kernel:  </TASK>
Dec 04 14:59:25 engel kernel: ---[ end trace 0000000000000000 ]---


6.1. did not show such a problem.

Both are vanilla stable kernels (self-built).

Regards,
-- 
Wolfgang Walter
Studierendenwerk München Oberbayern
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