Hello,

FYI this happens in v4.14-rc8 -- it's not necessarily a new bug.

[   22.626306] ide-cd: hdc: ATAPI 4X DVD-ROM drive, 512kB Cache
[   22.627216] cdrom: Uniform CD-ROM driver Revision: 3.20
[   22.638941] ide-cd: hdc: ATAPI 4X DVD-ROM drive, 512kB Cache
[   22.665149] rdac: device handler registered
[   22.666646] ACPI: Preparing to enter system sleep state S5
[   22.666764] BUG: unable to handle kernel NULL pointer dereference at 000001c0
[   22.666773] IP: cdrom_check_status+0x2c/0x90
[   22.666774] *pde = 00000000 
[   22.666777] Oops: 0000 [#1] SMP
[   22.666782] CPU: 1 PID: 155 Comm: kworker/1:2 Not tainted 4.14.0-rc8 #127
[   22.666783] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[   22.666788] Workqueue: events_freezable_power_ disk_events_workfn
[   22.666790] task: 4fe90980 task.stack: 507ac000
[   22.666792] EIP: cdrom_check_status+0x2c/0x90
[   22.666793] EFLAGS: 00210246 CPU: 1
[   22.666795] EAX: 00000000 EBX: 4fefec00 ECX: 00000000 EDX: 00000000
[   22.666796] ESI: 00000003 EDI: ffffffff EBP: 467a9340 ESP: 507aded0
[   22.666797]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[   22.666799] CR0: 80050033 CR2: 000001c0 CR3: 06e0f000 CR4: 00000690
[   22.666803] Call Trace:
[   22.666807]  ? ide_cdrom_check_events_real+0x1d/0x40
[   22.666811]  ? cdrom_check_events+0xe/0x30
[   22.666813]  ? disk_check_events+0x3a/0xf0
[   22.666817]  ? process_one_work+0x16a/0x370
[   22.666818]  ? process_one_work+0x117/0x370
[   22.666820]  ? worker_thread+0x31/0x3b0
[   22.666822]  ? kthread+0xd7/0x110
[   22.666824]  ? process_one_work+0x370/0x370
[   22.666826]  ? __kthread_create_on_node+0x160/0x160
[   22.666830]  ? ret_from_fork+0x19/0x30
[   22.666831] Code: 53 83 ec 14 89 c3 89 d1 be 03 00 00 00 65 a1 14 00 00 00 89 44 24 10 31 c0 8b 43 18 c7 44 24 04 00 00 00 00 c7 04 24 00 00 00 00 <8a> 80 c0 01 00 00 c7 44 24 08 00 00 00 00 83 e0 03 c7 44 24 0c
[   22.666863] EIP: cdrom_check_status+0x2c/0x90 SS:ESP: 0068:507aded0
[   22.666863] CR2: 00000000000001c0
[   22.666870] ---[ end trace 2410e586dd8f88b2 ]---
[   22.666872] Kernel panic - not syncing: Fatal exception

Attached the full dmesg and kconfig.

Thanks,
Fengguang