panic: assertion: p->p_lock == 0 in kern_wait

[YONETANI Tomokazu]

On Mon, Feb 21, 2011 at 01:41:26PM +0900, YONETANI Tomokazu wrote:
> Apparently a few hours of pbulk test can trigger this panic (this is
> on x86_64 and the kernel is built from source as of 5347900e6).
> As opposed to what KKASSERT claims, p->p_lock doesn't hold the non-zero
> value in the frame 5:
> 
			:
>   (kgdb) fr 5
>   #5  0xffffffff802989a1 in kern_wait (pid=<value optimized out>,
>       status=0xffffffe05e997a74, options=1528637672, rusage=0x0,
>       res=0xffffffe05e997b58) at /usr/src/sys/kern/kern_exit.c:901
>   901                             KKASSERT(p->p_lock == 0);
>   (kgdb) p p->p_lock
>   $1 = 0

After poking here and the, I think this KKASSERT() can simply go away
as proc_remove_zombie() will wait for p->p_lock to drop to zero anyway.

			/*
			 * Unlink the proc from its process group so that
			 * the following operations won't lead to an
			 * inconsistent state for processes running down
			 * the zombie list.
			 */
			KKASSERT(p->p_lock == 0);
			proc_remove_zombie(p);
			leavepgrp(p);