Re: FreeBSD 11.0-ALPHA5 r302256 kernel panic in filt_proc()

On 30 Jun, Konstantin Belousov wrote:
> On Wed, Jun 29, 2016 at 02:44:08PM -0700, Don Lewis wrote:
>> #10 0xffffffff80a02ddc in filt_proc (kn=0xfffff803c5679a80, 
>>     hint=<value optimized out>) at /usr/src/sys/kern/kern_event.c:473
>> #11 0xffffffff80a0173b in knote (list=<value optimized out>, hint=2147483648, 
>>     lockflags=<value optimized out>) at /usr/src/sys/kern/kern_event.c:2045
>> #12 0xffffffff80a0710e in exit1 (td=<value optimized out>, 
>>     rval=<value optimized out>, signo=<value optimized out>)
>>     at /usr/src/sys/kern/kern_exit.c:515
>> #13 0xffffffff80a0677d in sys_sys_exit (td=0xfffff803c5679a80, 
>>     uap=<value optimized out>) at /usr/src/sys/kern/kern_exit.c:178
>> #14 0xffffffff80eb8b2b in amd64_syscall (td=0xfffff80096b49500, traced=0)
>>     at subr_syscall.c:135
>> #15 0xffffffff80e98d9b in Xfast_syscall ()
>>     at /usr/src/sys/amd64/amd64/exception.S:396
>> #16 0x00000008009298ca in ?? ()
>> Previous frame inner to this frame (corrupt stack?)
>> Current language:  auto; currently minimal
>> (kgdb) 
>> 
>> 
>> The line numbers above seem to be off.  With kgdb from ports I see:
>> 
>> (kgdb) up
>> #12 filt_proc (kn=0xfffff803c5679a80, hint=<optimized out>)
>>     at /usr/src/sys/kern/kern_event.c:466
>> 466				kn->kn_data = KW_EXITCODE(p->p_xexit, p->p_xsig);
>> (kgdb) print kn
>> $1 = (struct knote *) 0xfffff803c5679a80
>> (kgdb) print p
>> $2 = (struct proc *) 0x0
>> 
> Please print out the knote, do 'p *kn'.  I am esp. interested in the
> kn->kn_status value.  It seems that the knote was already detached,

(kgdb) print *kn
$1 = {kn_link = {sle_next = 0x0}, kn_selnext = {sle_next = 0x0}, 
  kn_knlist = 0xfffff804a4770d40, kn_tqe = {tqe_next = 0x0, 
    tqe_prev = 0xfffff801b1581638}, kn_kq = 0xfffff801b1581600, kn_kevent = {
    ident = 70248, filter = -5, flags = 32816, fflags = 2147483648, data = 0, 
    udata = 0x0}, kn_status = 131, kn_sfflags = -2147483648, kn_sdata = 0, 
  kn_ptr = {p_fp = 0x0, p_proc = 0x0, p_aio = 0x0, p_lio = 0x0, 
    p_nexttime = 0x0, p_v = 0x0}, kn_fop = 0xffffffff818ed600 <proc_filtops>, 
  kn_hook = 0x0, kn_hookid = 0}