I was trying to run a bacula restore, but it complained about remote-sd communication. Turned out bacula-seed was not running on host machine. Service was started, but the issue still persisted. That's why I tried to test the tape library by running mtx -f /dev/sch0 Mtx completely froze my session. Mtx process was visible from ps but I was unable to kill it with any kill sig. Server was restarted again. Any attempt to use mtx hangs everything. Later I found out there was a trace in the syslog. Attached below:
[ 577.528026] BUG: unable to handle kernel NULL pointer dereference at 00000000000007a0
[ 577.528076] IP: scsi_device_get+0x5/0x70
[ 577.528095] PGD 0 P4D 0
[ 577.528111] Oops: 0000 [#1] SMP PTI
[ 577.528128] Modules linked in: ip_set ip6table_filter ip6_tables iptable_filter 8021q garp mrp bonding softdog nfnetlink_log nfnetlink dm_thin_pool dm_persistent_data dm_bio_prison dm_bufio libcrc32c intel_rapl sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc mgag200 aesni_intel ttm aes_x86_64 crypto_simd glue_helper cryptd drm_kms_helper drm intel_cstate dcdbas intel_rapl_perf i2c_algo_bit fb_sys_fops syscopyarea sysfillrect pcspkr sysimgblt ipmi_ssif ch joydev input_leds shpchp mei_me mei lpc_ich mac_hid wmi acpi_power_meter ipmi_si ipmi_devintf ipmi_msghandler zfs(PO) zunicode(PO) zavl(PO) icp(PO) dm_round_robin dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua zcommon(PO) znvpair(PO) spl(O) vhost_net vhost tap
[ 577.528457] ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi sunrpc ip_tables x_tables autofs4 btrfs xor zstd_compress raid6_pq osst st hid_generic usbkbd usbmouse usbhid hid ahci libahci tg3 ptp pps_core aic79xx scsi_transport_spi megaraid_sas
[ 577.528581] CPU: 1 PID: 4209 Comm: mtx Tainted: P O 4.15.18-23-pve #1
[ 577.528614] Hardware name: Dell Inc. PowerEdge R320/0KM5PX, BIOS 2.4.2 01/29/2015
[ 577.528649] RIP: 0010:scsi_device_get+0x5/0x70
[ 577.528669] RSP: 0018:ffffacd2c408bbc0 EFLAGS: 00010286
[ 577.528694] RAX: ffff88cfc85983c0 RBX: ffff88cfc85983c0 RCX: 0000000000000000
[ 577.528725] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[ 577.528755] RBP: ffffacd2c408bbe0 R08: 0000000000000000 R09: 0000000000000000
[ 577.528786] R10: 0000000000000040 R11: ffff88cfc99ede38 R12: ffff88cf83a23d00
[ 577.528817] R13: ffff88cfc714a780 R14: ffff88cfc0194060 R15: ffff88cf83a23d00
[ 577.528849] FS: 00007fb2d9017440(0000) GS:ffff88cfcea40000(0000) knlGS:0000000000000000
[ 577.528884] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 577.528909] CR2: 00000000000007a0 CR3: 00000007c3ab2001 CR4: 00000000001606e0
[ 577.528941] Call Trace:
[ 577.528960] ? ch_open+0x51/0xb0 [ch]
[ 577.528981] chrdev_open+0xbf/0x1a0
[ 577.529001] do_dentry_open+0x259/0x370
[ 577.529020] ? cdev_put+0x30/0x30
[ 577.529038] vfs_open+0x4f/0x80
[ 577.529056] path_openat+0x718/0x1630
[ 577.529075] ? unlock_page_memcg+0x12/0x20
[ 577.529096] ? page_add_file_rmap+0xf7/0x150
[ 577.529118] do_filp_open+0x99/0x110
[ 577.529137] ? __check_object_size+0x10b/0x1a0
[ 577.530248] ? __alloc_fd+0x46/0x170
[ 577.531360] do_sys_open+0x135/0x280
[ 577.532453] ? do_sys_open+0x135/0x280
[ 577.533532] SyS_open+0x1e/0x20
[ 577.534593] do_syscall_64+0x73/0x130
[ 577.535643] entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[ 577.536698] RIP: 0033:0x7fb2d8b3c6f0
[ 577.537753] RSP: 002b:00007ffe00ee6db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
[ 577.538838] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb2d8b3c6f0
[ 577.539916] RDX: 0000000000000004 RSI: 0000000000000002 RDI: 00007ffe00ee7e67
[ 577.540985] RBP: 00007ffe00ee7e67 R08: 0000561f9f4f12c0 R09: 00007fb2d8e0fba0
[ 577.542036] R10: 000000000000069f R11: 0000000000000246 R12: 0000000000000003
[ 577.543071] R13: 00000000ffffffff R14: 0000000000000000 R15: 0000000000000000
[ 577.544103] Code: e0 fb 3c 20 75 ba 80 7d cb 00 75 b4 b8 ea ff ff ff eb bd e8 1e 5e 9c ff 0f 1f 40 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 <8b> 87 a0 07 00 00 83 e8 03 83 f8 01 76 4a 55 48 89 e5 41 54 4c
[ 577.546269] RIP: scsi_device_get+0x5/0x70 RSP: ffffacd2c408bbc0
[ 577.547308] CR2: 00000000000007a0
[ 577.548360] ---[ end trace ded1d2c9c6631230 ]---
lsscsi:
[0:2:0:0] disk DELL PERC H310 2.12 /dev/sda
[0:2:1:0] disk DELL PERC H310 2.12 /dev/sdb
[1:0:0:0] tape HP Ultrium 3-SCSI D23U /dev/st0
[1:0:0:1] mediumx TANDBERG StorageLoader 0475 /dev/sch0
[6:0:0:0] cd/dvd PLDS DVD-ROM DS-8DBSH MD51 /dev/sr0
