Yes, upgrade to the latest kern/subr_pool.c and it should be ok.
I had the same problem, and chs found the cause.  :)

--Michael

Matthew Jacob <mjacob@feral.com> writes:

> Anyone else seen this recently?
> 
> panic: kernel diagnostic assertion "pcg->pcg_avail != 0" failed: file
> "../../../../kern/subr_pool.c", line 1692
> 
> Stopped in pid 5 (pagedaemon) at        cpu_Debugger+0x4:       ret
> zero,(ra
> )
> db> t
> cpu_Debugger() at cpu_Debugger+0x4
> panic() at panic+0x15c
> __assert() at __assert+0x34
> pool_cache_do_invalidate() at pool_cache_do_invalidate+0xa8
> pool_cache_reclaim() at pool_cache_reclaim+0x1c
> pool_reclaim() at pool_reclaim+0x58
> pool_drain() at pool_drain+0x90
> uvm_pageout() at uvm_pageout+0x164
> esigcode() at esigcode
> 
> -matt