Boot crash @hci_uart_tx_wakeup+0x38/0x148 w/ Linus' HEAD?

[John Stultz]

Hey folks,
   After updating to Linus' HEAD today, I'm seeing the following odd
boot time crash with the HiKey board (which uses the serdev driver).

[    1.963009] Unable to handle kernel read from unreadable memory at
virtual address 406f127000
[    1.963012] Mem abort info:
[    1.963015]   ESR = 0x96000005
[    1.963018]   Exception class = DABT (current EL), IL = 32 bits
[    1.963021]   SET = 0, FnV = 0
[    1.963023]   EA = 0, S1PTW = 0
[    1.963025] Data abort info:
[    1.963027]   ISV = 0, ISS = 0x00000005
[    1.963030]   CM = 0, WnR = 0
[    1.963032] [000000406f127000] user address but active_mm is swapper
[    1.963038] Internal error: Oops: 96000005 [#1] PREEMPT SMP
[    1.963046] CPU: 1 PID: 1282 Comm: kworker/u17:1 Not tainted
4.14.0-07281-g1b386f4 #666
[    1.963050] Hardware name: HiKey Development Board (DT)
[    1.963068] Workqueue: hci0 hci_cmd_work
[    1.963074] task: ffffffc0753c8000 task.stack: ffffff800b6c0000
[    1.963079] pstate: 80400005 (Nzcv daif +PAN -UAO)
[    1.963090] pc : hci_uart_tx_wakeup+0x38/0x148
[    1.963095] lr : hci_uart_tx_wakeup+0x30/0x148
[    1.963098] sp : ffffff800b6c3d10
[    1.963101] x29: ffffff800b6c3d10 x28: 0000000000000000
[    1.963107] x27: ffffffc074a79c78 x26: ffffffc07504d830
[    1.963112] x25: ffffff8008f76a30 x24: ffffffc07510a840
[    1.963117] x23: ffffffc07510aa10 x22: 0000000000000001
[    1.963122] x21: ffffff8008cd2000 x20: ffffffc0351cf288
[    1.963128] x19: ffffffc0351cf218 x18: 0000000000000000
[    1.963132] x17: 0000000000000000 x16: 0000000000000000
[    1.963137] x15: 0000000000000000 x14: ffffffc005fa1c00
[    1.963142] x13: 000000406f127000 x12: 0000000034d5d91d
[    1.963147] x11: 0000000000000400 x10: ffffffc077f8c480
[    1.963152] x9 : 0000000000000000 x8 : 0000000000000005
[    1.963157] x7 : 0000000000000000 x6 : ffffff8008f59e88
[    1.963162] x5 : 0000000000000003 x4 : 000000406f127000
[    1.963167] x3 : 0000000000000001 x2 : 000000406f127000
[    1.963172] x1 : ffffff8008cd2d28 x0 : 0000000000000000
[    1.963179] Process kworker/u17:1 (pid: 1282, stack limit =
0xffffff800b6c0000)
[    1.963182] Call trace:
[    1.963188]  hci_uart_tx_wakeup+0x38/0x148
[    1.963193]  hci_uart_send_frame+0x28/0x38
[    1.963197]  hci_send_frame+0x64/0xc0
[    1.963201]  hci_cmd_work+0x98/0x110
[    1.963209]  process_one_work+0x134/0x330
[    1.963214]  worker_thread+0x130/0x468
[    1.963220]  kthread+0xf8/0x128
[    1.963227]  ret_from_fork+0x10/0x18
[    1.963234] Code: 9134a2a0 97f3be03 f9402280 d538d082 (b8626801)
[    1.963239] ---[ end trace 457a26b9096bec64 ]---


I need to spend some more time doing more in depth debugging here, but
I have to close up for the night and run for dinner, so I wanted to
send out the initial report now.

thanks
-john