Re: kern/51877: carp related panic during shutdown

[christos%zoulas.com@localhost (Christos Zoulas)]

The following reply was made to PR kern/51877; it has been noted by GNATS.

From: christos%zoulas.com@localhost (Christos Zoulas)
To: gnats-bugs%NetBSD.org@localhost, kern-bug-people%netbsd.org@localhost, 
	gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, 
	Hauke Fath <hf%spg.tu-darmstadt.de@localhost>
Cc: 
Subject: Re: kern/51877: carp related panic during shutdown
Date: Wed, 18 Jan 2017 07:39:48 -0500

 On Jan 18,  7:05am, ozaki-r%netbsd.org@localhost (Ryota Ozaki) wrote:
 -- Subject: Re: kern/51877: carp related panic during shutdown
 
 | The following reply was made to PR kern/51877; it has been noted by GNATS.
 | 
 | From: Ryota Ozaki <ozaki-r%netbsd.org@localhost>
 | To: Hauke Fath <hf%spg.tu-darmstadt.de@localhost>
 | Cc: "gnats-bugs%NetBSD.org@localhost" <gnats-bugs%netbsd.org@localhost>, kern-bug-people%netbsd.org@localhost, 
 | 	gnats-admin%netbsd.org@localhost
 | Subject: Re: kern/51877: carp related panic during shutdown
 | Date: Wed, 18 Jan 2017 16:00:00 +0900
 | 
 |  On Tue, Jan 17, 2017 at 7:24 PM, Hauke Fath <hf%spg.tu-darmstadt.de@localhost> wrote:
 |  > On Tue, 17 Jan 2017 19:15:36 +0900, Ryota Ozaki wrote:
 |  >> Could you check where mutex_tryenter+0x12 is?
 |  >> (objdump -d netbsd |grep -A 30 'mutex_tryenter>:' or something)
 |  >
 |  > Attached.
 |  
 |  Thanks.
 |  
 |  The fault happened at MUTEX_SPIN_P(mtx) in mutex_tryenter perhaps
 |  because mtx is an invalid pointer (address). The mtx comes from
 |  this:
 |    l = curlwp;  // or l = owner below
 |    owner = (*l->l_syncobj->sobj_owner)(l->l_wchan);
 |    lwp_trylock(owner);
 |    mutex_tryenter(owner->l_mutex);
 |  
 |  IIUC, owner->l_mutex can be invalid if the adaptive mutex in question
 |  is destroyed or the owner of the mutex is disappeared holding the mutex
 |  for some reasons (or the data of the mutex is corrupted somehow).
 |  The former doesn't happen in this case as I said and also the latter
 |  is unlikely to happen.
 |  
 |  I don't have any ideas :-/ I hope clean build solves the issue.
 |    ozaki-r
 
 
 Can you put a printf in carp_detach carp_ifdetach and carp_clone_destroy
 and see when they are called during shutdown?
 
 christos