Comment 4 for bug 1804149

------- Comment From <email address hidden> 2018-11-20 15:44 EDT-------
(In reply to comment #6)
> Did this issue start happening after an update/upgrade?

Host run with latest maintenance updates associated with the installed kernel.

For this case, this issue has been seen twice on the host associated with this defect number

(a) 4.15.0-36-generic #39-Ubuntu - /var/dump/201811161956/dmesg.201811161956
(b) 4.15.0-23-generic #25-Ubuntu - /var/dump/201809121135/dmesg.201809121135

Most recently, provided with this defect number
(a) 4.15.0-36-generic #39-Ubuntu
/var/dump/201811161956
dmesg.201811161956
dump.201811161956

Prior occurrence was as follows
(b) 4.15.0-23-generic #25-Ubuntu
/var/dump/201809121135
dmesg.201809121135
dump.201809121135

Stack trace output:
dmesg.201809121135
[479123.425602] Unable to handle kernel pointer dereference in virtual kernel address space
[479123.425611] Failing address: 0000000000000000 TEID: 0000000000000483
[479123.425614] Fault in home space mode while using kernel ASCE.
[479123.425618] AS:0000000000e9c007 R3:00000000f37d0007 S:00000000f37ff000 P:000000000000013d
[479123.425672] Oops: 0004 ilc:3 [#1] SMP
[479123.425677] Modules linked in: iptable_filter binfmt_misc rpcsec_gss_krb5 auth_rpcgss nfsv4 nfs lockd grace fscache dasd_eckd_mod qeth_l3 qeth_l2 s390_trng ghash_s390 prng aes_s390 des_s390 des_generic sha512_s390 sha256_s390 sha1_s390 sha_common qeth vmur ccwgroup vfio_ccw vfio_mdev mdev vfio_iommu_type1 vfio sch_fq_codel ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp sunrpc libiscsi_tcp libiscsi scsi_transport_iscsi ip_tables x_tables dm_round_robin dm_service_time crc32_vx_s390 dasd_fba_mod dasd_mod zfcp qdio scsi_transport_fc scsi_dh_emc scsi_dh_rdac scsi_dh_alua dm_multipath
[479123.425724] CPU: 2 PID: 19195 Comm: kworker/u128:0 Not tainted 4.15.0-23-generic #25-Ubuntu
[479123.425731] Hardware name: IBM 3906 M05 7G4 (z/VM 7.1.0)
[479123.425744] Workqueue: iscsi_q_9 iscsi_xmitworker [libiscsi]
[479123.425746] Krnl PSW : 00000000a880894f 000000000803fc8a (__iscsi_get_task+0x6/0x18 [libiscsi])
[479123.425752] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3
[479123.425755] Krnl GPRS: 0000000084102000 000000005965fce0 0000000000000000 0000000080000400
[479123.425756] 000003ff801d7640 0000000000000008 00000000cded0000 000003ff801d77cc
[479123.425758] 000003ff801d769c 0000000000000000 0000000000000000 00000000cd0e0310
[479123.425759] 00000000f3689800 00000000cd0e03a2 000003ff801d2e8e 000000005965fc90
[479123.425771] Krnl Code: 000003ff801d2624: c0f4fffffcf6 brcl 15,3ff801d2010
000003ff801d262a: c0f40000377b brcl 15,3ff801d9520
#000003ff801d2630: c00400000000 brcl 0,3ff801d2630
>000003ff801d2636: eb012078006a asi 120(%r2),1
000003ff801d263c: c0f400003772 brcl 15,3ff801d9520
000003ff801d2642: 0707 bcr 0,%r7
000003ff801d2644: 0707 bcr 0,%r7
000003ff801d2646: 0707 bcr 0,%r7
[479123.425804] Call Trace:
[479123.425808] ([<000003ff801d2ec6>] iscsi_xmit_task+0x86/0x138 [libiscsi])
[479123.425810] [<000003ff801d769c>] iscsi_data_xmit+0x44c/0x548 [libiscsi]
[479123.425822] [<000003ff801d77cc>] iscsi_xmitworker+0x34/0x58 [libiscsi]
[479123.425831] [<0000000000191292>] process_one_work+0x262/0x4d8
[479123.425833] [<0000000000191560>] worker_thread+0x58/0x4e8
[479123.425838] [<00000000001986c4>] kthread+0x14c/0x168
[479123.425843] [<00000000008e174a>] kernel_thread_starter+0xa/0x10
[479123.425846] [<00000000008e1740>] kernel_thread_starter+0x0/0x10
[479123.425847] Last Breaking-Event-Address:
[479123.425850] [<000003ff801d2e88>] iscsi_xmit_task+0x48/0x138 [libiscsi]
[479123.425851]
[479123.425853] Kernel panic - not syncing: Fatal exception in interrupt