On Sun, 16 Oct 2016, Matthieu Herrb wrote:
> my Sabre Lite board paniced during the night for the 1st time in several 
> month. Here is the information I collected:
> kernel diagnostic assertion "p->p_wchan == NULL" failed: file 
> "/usr/src/sys/ker
> n/kern_sched.c", line 333

This means a thread was somehow in the CPU's run-queue...but had a wait 
channel as if it was waiting to be woken.

> ddb> ps
>    TID   PPID   PGRP    UID  S       FLAGS  WAIT          COMMAND
>  86009      0      0      0  2  0x40014200  miiaut        idle0

Bingo: S=2 --> SRUN!  Or in this case, WTF!?  idle threads must *NEVER* 
have a wait channel.  That smells like someone called tsleep() from an 
interrupt and arm doesn't have the low-level machinery to detect and panic 
at the call.

mii_phy_auto() is the source of the "miiaut" wait channel; are the mii 
flags not set right that it's taking the tsleep() path instead of 
timeout_* path?

Philip Guenther

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