RHEL8: kernel crashes at nfs4_get_valid_delegation+0x6 in NFSv4

Issue

• kernel crashes with following logs:

[5544590.604096] BUG: unable to handle kernel paging request at ffffffffffffffb0
[5544590.605715] PGD 136ea0d067 P4D 136ea0d067 PUD 136ea0f067 PMD 0 
[5544590.606448] Oops: 0000 [#1] SMP PTI
[5544590.607139] CPU: 10 PID: 2583219 Comm: kworker/u34:0 Kdump: loaded Not tainted 4.18.0-193.el8.x86_64 #1
[5544590.607818] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 12/12/2018
[5544590.608573] Workqueue: rpciod rpc_async_schedule [sunrpc]
[5544590.609318] RIP: 0010:nfs4_get_valid_delegation+0x6/0x30 [nfsv4]
[5544590.610048] Code: 5c 41 5d 41 5e 41 5f e9 c8 f9 ff ff 45 31 ff e9 54 fe ff ff 66 66 66 66 90 f0 80 4f 48 08 c3 0f 1f 44 00 00 66 66 66 66 90 53 <48> 8b 5f b0 31 f6 48 89 df e8 0c f9 ff ff 84 c0 b8 00 00 00 00 48
[5544590.611584] RSP: 0018:ffffc14a1a82bdf8 EFLAGS: 00010246
[5544590.612489] RAX: ffff9d55e68cafc0 RBX: ffff9d75d6d7a400 RCX: 0000000000000004
[5544590.613570] RDX: 0000000000008100 RSI: 0000000000000001 RDI: 0000000000000000
[5544590.614507] RBP: ffff9d75d3afd100 R08: 0000000000000000 R09: 0000646f69637072
[5544590.615733] R10: 8080808080808080 R11: 0000000000000001 R12: 0000000000000004
[5544590.616701] R13: ffff9d6eabfa4c00 R14: ffffffffc0538ca0 R15: ffffffffc0536a70
[5544590.617537] FS:  0000000000000000(0000) GS:ffff9d75ffa80000(0000) knlGS:0000000000000000
[5544590.618511] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[5544590.619442] CR2: ffffffffffffffb0 CR3: 000000136ea0a001 CR4: 00000000000606e0
[5544590.620284] Call Trace:
[5544590.621104]  nfs4_open_prepare+0x80/0x1d0 [nfsv4]
[5544590.621936]  __rpc_execute+0x85/0x340 [sunrpc]
[5544590.622759]  rpc_async_schedule+0x29/0x40 [sunrpc]
[5544590.623557]  process_one_work+0x1a7/0x3b0
[5544590.624341]  worker_thread+0x30/0x390
[5544590.625122]  ? create_worker+0x1a0/0x1a0
[5544590.626056]  kthread+0x112/0x130
[5544590.626915]  ? kthread_flush_work_fn+0x10/0x10
[5544590.627662]  ret_from_fork+0x35/0x40
[5544590.628401] Modules linked in: rpcsec_gss_krb5 nfsv4 dns_resolver lp parport tcp_diag udp_diag inet_diag nf_tables nfnetlink nfsv3 nfs_acl nfs lockd grace fscache vmw_vsock_vmci_transport vsock binfmt_misc intel_rapl_msr intel_rapl_common sb_edac crct10dif_pclmul crc32_pclmul ghash_clmulni_intel vmw_balloon intel_rapl_perf joydev pcspkr vmw_vmci i2c_piix4 auth_rpcgss sunrpc ip_tables xfs libcrc32c sr_mod cdrom ata_generic vmwgfx sd_mod sg drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm ata_piix crc32c_intel serio_raw libata vmxnet3 vmw_pvscsi dm_mirror dm_region_hash dm_log dm_mod
[5544590.632180] CR2: ffffffffffffffb0