FYI, we noticed the below changes on git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master commit 4edd70c133f3921c594883d8f9da31a7261f8b4f ("auxdisplay: ks0108: use new parport device model") +------------------------------------------+------------+------------+ | | c9efdbe634 | 4edd70c133 | +------------------------------------------+------------+------------+ | boot_successes | 72 | 0 | | boot_failures | 0 | 32 | | BUG:unable_to_handle_kernel | 0 | 32 | | Oops | 0 | 32 | | EIP_is_at_ks0108_writecontrol | 0 | 32 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 32 | | backtrace:cfag12864b_page | 0 | 32 | | backtrace:cfag12864b_init | 0 | 32 | | backtrace:kernel_init_freeable | 0 | 32 | +------------------------------------------+------------+------------+ [ 1.646998] device id = 2670 [ 1.648297] slram: not enough parameters. [ 1.648297] slram: not enough parameters. [ 1.655191] BUG: unable to handle kernel [ 1.655191] BUG: unable to handle kernel NULL pointer dereferenceNULL pointer dereference at 00000368 at 00000368 [ 1.656053] IP: [ 1.656053] IP: [<41505410>] ks0108_writecontrol+0x20/0x30 [<41505410>] ks0108_writecontrol+0x20/0x30 [ 1.656053] *pde = 00000000 [ 1.656053] *pde = 00000000 [ 1.656053] Oops: 0000 [#1] [ 1.656053] Oops: 0000 [#1] DEBUG_PAGEALLOC DEBUG_PAGEALLOC [ 1.656053] Modules linked in: [ 1.656053] Modules linked in: [ 1.656053] CPU: 0 PID: 1 Comm: swapper Not tainted 4.2.0-rc4-00102-g4edd70c #567 [ 1.656053] CPU: 0 PID: 1 Comm: swapper Not tainted 4.2.0-rc4-00102-g4edd70c #567 [ 1.656053] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014 [ 1.656053] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014 [ 1.656053] task: 40256040 ti: 40266000 task.ti: 40266000 [ 1.656053] task: 40256040 ti: 40266000 task.ti: 40266000 [ 1.656053] EIP: 0060:[<41505410>] EFLAGS: 00010247 CPU: 0 [ 1.656053] EIP: 0060:[<41505410>] EFLAGS: 00010247 CPU: 0 [ 1.656053] EIP is at ks0108_writecontrol+0x20/0x30 [ 1.656053] EIP is at ks0108_writecontrol+0x20/0x30 [ 1.656053] EAX: 00000000 EBX: 4197800a ECX: 00000000 EDX: 0000000a [ 1.656053] EAX: 00000000 EBX: 4197800a ECX: 00000000 EDX: 0000000a [ 1.656053] ESI: 00000000 EDI: 504fc120 EBP: 40267eec ESP: 40267ee8 [ 1.656053] ESI: 00000000 EDI: 504fc120 EBP: 40267eec ESP: 40267ee8 [ 1.656053] DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 [ 1.656053] DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 [ 1.656053] CR0: 8005003b CR2: 00000368 CR3: 01c2e000 CR4: 00000690 [ 1.656053] CR0: 8005003b CR2: 00000368 CR3: 01c2e000 CR4: 00000690 [ 1.656053] Stack: [ 1.656053] Stack: [ 1.656053] 41978000 [ 1.656053] 41978000 40267ef4 40267ef4 415055f7 415055f7 40267f00 40267f00 4150561c 4150561c 41978040 41978040 40267f10 40267f10 41bc9eb0 41bc9eb0 [ 1.656053] 419780c0 [ 1.656053] 419780c0 41bc9de7 41bc9de7 40267f84 40267f84 41000442 41000442 000000d0 000000d0 418b5342 418b5342 41bc9de7 41bc9de7 00000160 00000160 [ 1.656053] 41971508 [ 1.656053] 41971508 40267f70 40267f70 410693af 410693af 00000000 00000000 00000000 00000000 40267f44 40267f44 4108940b 4108940b 00000006 00000006 [ 1.656053] Call Trace: [ 1.656053] Call Trace: [ 1.656053] [<415055f7>] cfag12864b_e+0x37/0x40 [ 1.656053] [<415055f7>] cfag12864b_e+0x37/0x40 [ 1.656053] [<4150561c>] cfag12864b_page+0x1c/0x30 [ 1.656053] [<4150561c>] cfag12864b_page+0x1c/0x30 [ 1.656053] [<41bc9eb0>] cfag12864b_init+0xc9/0x127 [ 1.656053] [<41bc9eb0>] cfag12864b_init+0xc9/0x127 [ 1.656053] [<41bc9de7>] ? ks0108_init+0x16/0x16 [ 1.656053] [<41bc9de7>] ? ks0108_init+0x16/0x16 [ 1.656053] [<41000442>] do_one_initcall+0x82/0x1f0 [ 1.656053] [<41000442>] do_one_initcall+0x82/0x1f0 [ 1.656053] [<41bc9de7>] ? ks0108_init+0x16/0x16 [ 1.656053] [<41bc9de7>] ? ks0108_init+0x16/0x16 [ 1.656053] [<410693af>] ? parse_args+0x1df/0x410 [ 1.656053] [<410693af>] ? parse_args+0x1df/0x410 [ 1.656053] [<4108940b>] ? trace_hardirqs_on+0xb/0x10 [ 1.656053] [<4108940b>] ? trace_hardirqs_on+0xb/0x10 [ 1.656053] [<41b9ac44>] ? kernel_init_freeable+0x16c/0x209 [ 1.656053] [<41b9ac44>] ? kernel_init_freeable+0x16c/0x209 [ 1.656053] [<41b9ac64>] kernel_init_freeable+0x18c/0x209 [ 1.656053] [<41b9ac64>] kernel_init_freeable+0x18c/0x209 [ 1.656053] [<4168cbe0>] kernel_init+0x10/0xe0 [ 1.656053] [<4168cbe0>] kernel_init+0x10/0xe0 [ 1.656053] [<41073827>] ? schedule_tail+0x17/0x60 [ 1.656053] [<41073827>] ? schedule_tail+0x17/0x60 [ 1.656053] [<416a2de0>] ret_from_kernel_thread+0x20/0x30 [ 1.656053] [<416a2de0>] ret_from_kernel_thread+0x20/0x30 [ 1.656053] [<4168cbd0>] ? rest_init+0x120/0x120 [ 1.656053] [<4168cbd0>] ? rest_init+0x120/0x120 [ 1.656053] Code: [ 1.656053] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 55 89 89 e5 e5 53 53 3e 3e 8d 8d 74 74 26 26 00 00 88 88 c3 c3 a1 a1 60 60 9d 9d b1 b1 41 41 80 80 f3 f3 0b 0b e8 e8 78 78 60 60 e9 e9 ff ff a1 a1 b4 b4 e5 e5 4c 4c 42 42 0f 0f b6 b6 d3 d3 <8b> <8b> 88 88 68 68 03 03 00 00 00 00 ff ff 51 51 08 08 5b 5b 5d 5d c3 c3 8d 8d 74 74 26 26 00 00 55 55 89 89 e5 e5 83 83 ec ec [ 1.656053] EIP: [<41505410>] [ 1.656053] EIP: [<41505410>] ks0108_writecontrol+0x20/0x30ks0108_writecontrol+0x20/0x30 SS:ESP 0068:40267ee8 SS:ESP 0068:40267ee8 [ 1.656053] CR2: 0000000000000368 [ 1.656053] CR2: 0000000000000368 [ 1.656053] ---[ end trace 2eb5b9886d7036ac ]--- [ 1.656053] ---[ end trace 2eb5b9886d7036ac ]--- Thanks, Ying Huang