** Tags removed: targetmilestone-inin--- verification-needed-jammy
** Tags added: targetmilestone-inin2204 verification-done-jammy

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https://bugs.launchpad.net/bugs/1980951

Title:
  [UBUNTU 22.04] Kernel oops while removing device from cio_ignore list

Status in Ubuntu on IBM z Systems:
  Fix Committed
Status in linux package in Ubuntu:
  Invalid
Status in linux source package in Jammy:
  Fix Committed

Bug description:
  SRU Justification:
  ==================

  [Impact]

   * A kernel Oops occurs when a device is removed from the cio_ignore list
     (that is used to hide ccw devices) on a system with non-I/O subchannels
     (e.g. SCM or CHSC subchannels).

   * As a result, previously ignored devices cannot be activated again,
     and new devices cannot be found.

  [Fix]

   * 0c3812c347bf 0c3812c347bfb0dc213556a195e79850c55702f5 "s390/cio:
  derive cdev information only for IO-subchannels"

  [Test Plan]

   * An IBM zSystems or LinuxONE LPAR with with non-I/O subchannels.

   * Ubuntu Server 22.04 LTS (with GA kernel 5.15) installed.

   * Define a cio_ignore list (to hide ccw devices).

   * Remove a device from the cio_ignore list.

   * Due to hardware requirements this test needs to be conducted by
  IBM.

  [Where problems could occur]

   * General problems may occur with ccw device activation/deactivation
     in case the new initialization is erroneous.

   * Issues may also have an impact on the type of ccw devices,
     and may no longer be limited to non-I/O subchannels.

   * Things could still go wrong in case cdev is still not properly
     derived from sch-type SUBCHANNEL_TYPE_IO.

  [Other Info]
   
   * The commit is upstream since kernel 5.16 (next-20220315).
  __________

  ---Problem Description from Peter---
  A kernel oops occurs when a device is removed from the cio_ignore list on a 
system with non-I/O subchannels (e.g. SCM or CHSC subchannels). As a result, 
previously ignored devices cannot be activated, and new devices cannot be found.

  ---uname output---
  Linux localhost 5.15.0-40-generic #43-Ubuntu SMP Wed Jun 15 12:53:53 UTC 2022 
s390x s390x s390x GNU/Linux

  Machine Type = s390x

  ---Steps to Reproduce---
  On an s390x-LPAR with non-I/O subchannels, remove a device from the 
cio_ignore list.

  Oops output:
   [   51.597505] Unable to handle kernel pointer dereference in virtual kernel 
address space
  [   51.597516] Failing address: 2081e99191e98000 TEID: 2081e99191e98803
  [   51.597520] Fault in home space mode while using kernel ASCE.
  [   51.597524] AS:0000000082adc007 R3:0000000000000024
  [   51.597665] Oops: 0038 ilc:3 [#1] SMP
  [   51.597671] Modules linked in: scm_block chsc_sch vfio_ccw mdev 
vfio_iommu_type1 vfio eadm_sch sch_fq_codel dm_multipath scsi_dh_rdac 
scsi_dh_emc scsi_dh_alua drm i2c_core drm_panel_orientation_quirks ip_tables 
x_tables btrfs blake2b_generic zstd_compress raid10 raid456 async_raid6_recov 
async_memcpy async_pq async_
  xor async_tx xor raid6_pq libcrc32c raid1 raid0 linear pkey zcrypt 
crc32_vx_s390 ghash_s390 prng chacha_s390 libchacha aes_s390 des_s390 libdes 
qeth_l2 bridge stp llc zfcp qeth qdio scsi_transport_fc ccwgroup sha512_s390 
sha256_s390 sha1_s390 sha_common
  [   51.597735] CPU: 6 PID: 1418 Comm: cio_ignore Not tainted 
5.15.0-40-generic #43-Ubuntu
  [   51.597740] Hardware name: IBM 2964 NC9 702 (LPAR)
  [   51.597742] Krnl PSW : 0704e00180000000 0000000081b0c632 
(__unset_online+0x22/0x70)
  [   51.597752]            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
  [   51.597756] Krnl GPRS: 0000000000000001 00000000004a3ca8 0000038007e49000 
2081e99191e98528
  [   51.597760]            0000000000000000 0000000081b0c610 0000000000000000 
0000000081b07f10
  [   51.597762]            000002aa00000000 0000000081b0c610 0000038007e49000 
0000038007a6bc98
  [   51.597765]            00000000941f9200 000003ffa8cf95e0 0000000081818900 
0000038007a6bbf8
  [   51.597773] Krnl Code: 0000000081b0c624: a784000c            brc     
8,0000000081b0c63c
  [   51.597773]            0000000081b0c628: e33030200002        ltg     
%r3,32(%r3)
  [   51.597773]           #0000000081b0c62e: a7840007            brc     
8,0000000081b0c63c
  [   51.597773]           >0000000081b0c632: e33032000012        lt      
%r3,512(%r3)
  [   51.597773]            0000000081b0c638: a7740007            brc     
7,0000000081b0c646
  [   51.597773]            0000000081b0c63c: a7290000            lghi    %r2,0
  [   51.597773]            0000000081b0c640: c0f400089854        brcl    
15,0000000081c1f6e8
  [   51.597773]            0000000081b0c646: ebeff0880024        stmg    
%r14,%r15,136(%r15)
  [   51.597818] Call Trace:
  [   51.597820]  [<0000000081b0c632>] __unset_online+0x22/0x70
  [   51.597824] ([<00000000818188e6>] bus_for_each_dev+0x66/0xc0)
  [   51.597828]  [<0000000081b0e378>] css_schedule_eval_cond+0xe8/0x130
  [   51.597832]  [<0000000081b08062>] cio_ignore_write+0x152/0x190
  [   51.597838]  [<00000000814be36e>] proc_reg_write+0x9e/0xf0
  [   51.597843]  [<00000000813f3470>] vfs_write+0xc0/0x280
  [   51.597848]  [<00000000813f59a8>] ksys_write+0x68/0x100
  [   51.597852]  [<0000000081b495d0>] __do_syscall+0x1c0/0x1f0
  [   51.597857]  [<0000000081b56858>] system_call+0x78/0xa0
  [   51.597862] Last Breaking-Event-Address:
  [   51.597864]  [<000000000000a000>] 0xa000
  [   51.597868] ---[ end trace 166ba86e913d2c60 ]---

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