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Date: Sun, 22 Feb 2015 20:53:52 +0200
From: Konstantin Belousov <kostikbel@gmail.com>
To: sbruno@freebsd.org
Subject: Re: panic on application core dump?
Message-ID: <20150222185352.GL74514@kib.kiev.ua>
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On Sun, Feb 22, 2015 at 10:46:53AM -0800, Sean Bruno wrote:
> Hmm ... looks unrelated to signals (maybe).  This looks like a common
> ZFS deadlock that is yet undiagnosed.  I do not have a show alllocks
> command available in db> .  I will show each lock information below:
Add witness.

> 
> db> show lockedvnods
> Locked vnodes
> 
> 0xfffff801141a6588: tag zfs, type VDIR
>     usecount 19, writecount 0, refcount 20 mountedhere 0
>     flags (VV_ROOT|VI_ACTIVE)
>     v_object 0xfffff80079be4500 ref 0 pages 0 cleanbuf 0 dirtybuf 0
>     lock type zfs: EXCL by thread 0xfffff801ca10c4a0 (pid 75907, sh,
> tid 101262)
>  with exclusive waiters pending
Without backtraces of the acquisition, it is not useful.  You need
DEBUG_VFS_LOCKS for this.