Re: kern/51877: carp related panic during shutdown

[Ryota Ozaki <ozaki-r%netbsd.org@localhost>]

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