Comment 10 for bug 1824981

Yes, it happend once with 4.18.0-17 (see kernel.log below) and once with 4.15.0-48. Haven't seen this one on 4.15.0-46-generic or 4.15.0-47-generic before.

Apr 17 18:51:53 Linux version 4.18.0-17-generic (buildd@lgw01-amd64-021) (gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3)) #18~18.04.1-Ubuntu SMP Fri Mar 15 15:27:12 UTC 2019 (Ubuntu 4.18.0-17.18~18.04.1-generic 4.18.20)
Apr 17 18:51:53 Command line: BOOT_IMAGE=/boot/vmlinuz-4.18.0-17-generic root=UUID=7d58d6b0-bdf2-4a7b-bfde-d28a5ea498f6 ro
[...]
Apr 17 21:01:31 CIFS VFS: error -95 on ioctl to get interface list
[...]
Apr 17 21:43:48 perf: interrupt took too long (6290 > 6260), lowering kernel.perf_event_max_sample_rate to 31750
Apr 17 21:57:28 BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
Apr 17 21:57:28 PGD 0 P4D 0
Apr 17 21:57:28 Oops: 0000 [#1] SMP PTI
Apr 17 21:57:28 CPU: 13 PID: 21224 Comm: kworker/13:2 Not tainted 4.18.0-17-generic #18~18.04.1-Ubuntu
Apr 17 21:57:28 Hardware name: Dell Inc. PowerEdge R900/0X947H, BIOS 1.2.0 11/11/2010
Apr 17 21:57:28 Workqueue: cifsoplockd cifs_oplock_break [cifs]
Apr 17 21:57:28 RIP: 0010:smb2_push_mandatory_locks+0xd5/0x5d0 [cifs]
Apr 17 21:57:28 Code: b0 49 39 c6 0f 84 2d 01 00 00 c7 45 c4 00 00 00 00 [...]
Apr 17 21:57:28 RSP: 0018:ffff9f6d481d7de8 EFLAGS: 00010246
Apr 17 21:57:28 RAX: 0000000000000000 RBX: ffff94016f151798 RCX: ffffe793bfc47c00
Apr 17 21:57:28 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff9401711f0000
Apr 17 21:57:28 RBP: ffff9f6d481d7e38 R08: 0000000000028160 R09: ffffe793bfc47c00
Apr 17 21:57:28 R10: 0000000000000002 R11: ffff9401711e0000 R12: 0000000000000aaa
Apr 17 21:57:28 R13: ffff94016f151798 R14: ffff94016f151780 R15: ffff94016e435e00
Apr 17 21:57:28 FS: 0000000000000000(0000) GS:ffff94017f140000(0000) knlGS:0000000000000000
Apr 17 21:57:28 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Apr 17 21:57:28 CR2: 0000000000000038 CR3: 0000000fdb406000 CR4: 00000000000006e0
Apr 17 21:57:28 Call Trace:
Apr 17 21:57:28 ? cifs_revalidate_mapping+0x45/0x90 [cifs]
Apr 17 21:57:28 cifs_oplock_break+0x124/0x410 [cifs]
Apr 17 21:57:28 process_one_work+0x1fd/0x3f0
Apr 17 21:57:28 worker_thread+0x34/0x410
Apr 17 21:57:28 kthread+0x121/0x140
Apr 17 21:57:28 ? process_one_work+0x3f0/0x3f0
Apr 17 21:57:28 ? kthread_create_worker_on_cpu+0x70/0x70
Apr 17 21:57:28 ret_from_fork+0x35/0x40
Apr 17 21:57:28 Modules linked in: ipmi_si mpt3sas raid_class mptctl mptbase arc4 md4 cmac nls_utf8 cifs ccm fscache nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack libcrc32c iptable_filter bpfilter dell_rbu binfmt_misc ipmi_ssif radeon ttm drm_kms_helper coretemp drm i2c_algo_bit fb_sys_fops syscopyarea sysfillrect gpio_ich kvm lpc_ich input_leds joydev sysimgblt ipmi_devintf irqbypass sch_fq_codel serio_raw dcdbas ipmi_msghandler mac_hid i7300_edac bonding lp parport ip_tables x_tables autofs4 ses enclosure scsi_transport_sas hid_generic usbhid hid psmouse bnx2 megaraid_sas pata_acpi [last unloaded: ipmi_si]
Apr 17 21:57:28 CR2: 0000000000000038
Apr 17 21:57:28 ---[ end trace 6742ba53428dc499 ]---
Apr 17 21:57:28 RIP: 0010:smb2_push_mandatory_locks+0xd5/0x5d0 [cifs]
Apr 17 21:57:28 Code: b0 49 39 c6 0f 84 2d 01 00 00 c7 45 c4 00 00 00 00 [...]
Apr 17 21:57:28 RSP: 0018:ffff9f6d481d7de8 EFLAGS: 00010246
Apr 17 21:57:28 RAX: 0000000000000000 RBX: ffff94016f151798 RCX: ffffe793bfc47c00
Apr 17 21:57:28 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff9401711f0000
Apr 17 21:57:28 RBP: ffff9f6d481d7e38 R08: 0000000000028160 R09: ffffe793bfc47c00
Apr 17 21:57:28 R10: 0000000000000002 R11: ffff9401711e0000 R12: 0000000000000aaa
Apr 17 21:57:28 R13: ffff94016f151798 R14: ffff94016f151780 R15: ffff94016e435e00
Apr 17 21:57:28 FS: 0000000000000000(0000) GS:ffff94017f140000(0000) knlGS:0000000000000000
Apr 17 21:57:28 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Apr 17 21:57:28 CR2: 0000000000000038 CR3: 0000000fdb406000 CR4: 00000000000006e0
Apr 17 21:58:55 perf: interrupt took too long (7881 > 7862), lowering kernel.perf_event_max_sample_rate to 25250