Re: kern/53005: apache httpd can hang the system

[clare%csel.org@localhost]

On Mon, 12 Feb 2018 19:20:01 +0000 (UTC)
Manuel Bouyer <bouyer%antioche.eu.org@localhost> wrote:

> From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
> To: clare%csel.org@localhost
> Cc: gnats-bugs%NetBSD.org@localhost, kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
>         netbsd-bugs%netbsd.org@localhost
> Subject: Re: kern/53005: apache httpd can hang the system
> Date: Mon, 12 Feb 2018 20:18:06 +0100
> 
>  On Mon, Feb 12, 2018 at 03:40:38PM +0900, clare%csel.org@localhost wrote:
>  > >  When it hangs, can you enter ddb and get a backtrace of the apache process ?
>  > 
>  > db{0}> bt
>  > breakpoint() at netbsd:breakpoint+0x5
>  > wskbd_translate() at netbsd:wskbd_translate+0xbb4
>  > wskbd_input() at netbsd:wskbd_input+0x5b
>  > pckbd_input() at netbsd:pckbd_input+0x6b
>  > pckbcintr() at netbsd:pckbcintr+0x8d
>  > intr_bloglock_wrapper() at netbsd:intr_biglock_wrapper+0x1d
>  > Xintr_ioapic_edge4() at netbsd:Xintr_ioapic_edge4+0xf1
>  > --- interrupt ---
>  > exit_lwps() at netbsd:exit_lwps+0x58
>  > exit1() at netbsd:exit1+0x68
>  > sys_exit() at netbsd:sys_eit+0x3d
>  > syscall() at netbsd:syscall+0x1d8
>  > --- syscall (number 1) ---
>  > 
>  > db{0}> trace/t 50
>  > trace: pid 80 lid 40 at 0xffff80002a503db0
>  > ?() at ffffe4001fa3b5c0
>  > lwp_exit_switchaway() at netbsd:lwp_exit_switchaway+0x1ac
>  > Bad frame pointer: 0xffffe4001a1c8300
>  
>  Do you want to backtrace pid 50 (decimal) or 80 (decimal) ?
>  if you want to trace pid 50, you have to use:
>  trace/t 0t50
>  (numbers are interpreted as hex by default).

the PID was 80 as of showing ps command in ddb.
i thounght 80 was shown in decimal.

screenshot is here:
https://www.csel.org/netbsd/pr/53005/ddb-2018-2-12.png


>  Also it would be interesting to see which pid was interupted by entering ddb.
>  I wonder if it's stuck looping in exit_lwps()

I cannot reproduce the problem on the bare metal multiprocessor local
machine, currently.

when I enabled both LOCKDEBUG and DEBUG options, then problem was gone.

when I enabled DEBUG and without LOCKDEBUG options, then problem was gone.

when I enabled LOCKDEBUG and without DEBUG options, then problem was appeared,
screenshots are in https://www.csel.org/netbsd/pr/53005/lockdebug/


-- 
Shinichi Doyashiki <clare%csel.org@localhost>