Kernel panic,iSCSI,Unable to handle kernel pointer dereference in virtual kernel address space

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Description will follow

[bugproxy (bugproxy)]

------- Comment From <email address hidden> 2018-07-17 03:53 EDT-------
---Problem Description---
Kernel panic,Unable to handle kernel pointer dereference in virtual kernel address space

Contact Information = Michael <email address hidden>

---uname output---
Linux ilzlnx4 4.15.0-15-generic #16-Ubuntu SMP Wed Apr 4 13:57:26 UTC 2018 s390x s390x s390x GNU/Linux

Machine Type = s390x

---Debugger---
A debugger is not configured

---Steps to Reproduce---
1 - IO running to iscsi luns
2 - Error inject running was storage side switch port bounce (off/on)

Stack trace output:
"ilzlnx4 login:"
"[551709.743278] Unable to handle kernel pointer dereference in virtual kernel ad"
"dress space"
"[551709.743952] Failing address: 0000000000000000 TEID: 0000000000000483"
"[551709.743955] Fault in home space mode while using kernel ASCE."
"[551709.743959] AS:0000000000eb0007 R3:00000001f3bd0007 S:00000001f3bd4000 P:000"
000000000013d
"[551709.743990] Oops: 0004 ilc:3 [#1] SMP"
"[551709.743994] Modules linked in: iptable_filter binfmt_misc rpcsec_gss_krb5 au"
"th_rpcgss nfsv4 nfs lockd grace fscache dm_round_robin dm_service_time dm_multip"
"ath scsi_dh_rdac scsi_dh_emc scsi_dh_alua qeth_l2 s390_trng ghash_s390 prng aes_"
"s390 des_s390 des_generic sha512_s390 sha256_s390 sha1_s390 sha_common chsc_sch"
"eadm_sch qeth qdio ccwgroup vfio_ccw vfio_mdev mdev vfio_iommu_type1 vfio sch_fq"
"_codel ib_iser rdma_cm iw_cm sunrpc ib_cm ib_core iscsi_tcp libiscsi_tcp libiscs"
"i scsi_transport_iscsi ip_tables x_tables crc32_vx_s390 dasd_eckd_mod dasd_mod"
"[551709.744079] CPU: 2 PID: 39417 Comm: kworker/u512:1 Not tainted 4.15.0-15-gen"
"eric #16-Ubuntu"
"[551709.744083] Hardware name: IBM 3906 M05 7G4 (LPAR)"
"[551709.744099] Workqueue: iscsi_q_3 iscsi_xmitworker [libiscsi]"
"[551709.744104] Krnl PSW : 0000000006270506 00000000152bbcbd (__iscsi_get_task+0"
"x6/0x18 [libiscsi])"
"[551709.744148] 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"
"[551709.744154] Krnl GPRS: 0000000000000008 00000001e0e3fce0 0000000000000000 00"
00000080000400
"[551709.744339] 000003ff80126640 0000000000000000 00000001e4f0e400 00"
0003ff801267cc
"[551709.744342] 000003ff8012669c 0000000000000000 0000000000000000 00"
000001e161ab10
"[551709.744937] 00000001f3a93000 00000001e161aba2 000003ff80121e8e 00"
000001e0e3fc90
"[551709.745123] Krnl Code: 000003ff80121624: c0f4fffffcf6 brcl 15,3ff80"
121010
"[551709.745123] 000003ff8012162a: c0f40000377b brcl 15,3ff80"
128520
"[551709.745123] #000003ff80121630: c00400000000 brcl 0,3ff801"
21630
"[551709.745123] >000003ff80121636: eb012078006a asi 120(%r2)"
",1"
"[551709.745123] 000003ff8012163c: c0f400003772 brcl 15,3ff80"
128520
"[551709.745123] 000003ff80121642: 0707 bcr 0,%r7"
"[551709.745123] 000003ff80121644: 0707 bcr 0,%r7"
"[551709.745123] 000003ff80121646: 0707 bcr 0,%r7"
"[551709.745246] Call Trace:"
"[551709.745441] ([<000003ff80121ec6>] iscsi_xmit_task+0x86/0x138 [libiscsi])"
"[551709.745450] [<000...

[Frank Heimes (fheimes)]

I'm wondering why a pre-GA bionic (according to the tags) kernel was used?
==> 4.15.0-15

The GA kernel was 4.15.0.20 and we are now in between on an even higher level:
 linux-generic | 4.15.0.20.23 | bionic | s390x
 linux-generic | 4.15.0.23.25 | bionic-security | s390x
 linux-generic | 4.15.0.23.25 | bionic-updates | s390x
( linux-generic | 4.15.0.28.30 | bionic-proposed | s390x)

Please always make sure that you are on the latest kernel level!
(Of course not necessarily on the proposed level ...)

Does that also happen with the current/latest kernel?

[bugproxy (bugproxy)]

------- Comment From <email address hidden> 2018-07-24 18:04 EDT-------
In response to
>Does that also happen with the current/latest kernel?

Host has been update to 4.15.0-23-generic
i.e.
root@ilzlnx4:~# uname -a
Linux ilzlnx4 4.15.0-23-generic #25-Ubuntu SMP Wed May 23 17:58:29 UTC 2018 s390x s390x s390x GNU/Linux
root@ilzlnx4:~#

No new occurrences of kernel panic and continuing to monitor

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------- Comment From <email address hidden> 2018-08-02 19:53 EDT-------
This bugzilla defect can be closed.
No new occurrences of kernel panic since updating kernel from 4.15.0-15-generic to 4.15.0-23-generic on 07162018

[bugproxy (bugproxy)]

------- Comment From <email address hidden> 2018-08-03 02:48 EDT-------
IBM Bugzilla status -> closed; Problem solved with latest kernel