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Date:      Mon, 06 Apr 2015 16:09:03 -0400
From:      John Baldwin <jhb@freebsd.org>
To:        freebsd-current@freebsd.org
Cc:        Lars <lars@odin-corporation.com>
Subject:   Re: Is a high witness refcount indicative of a missing unlock?
Message-ID:  <238127021.hvy73srvVG@ralph.baldwin.cx>
In-Reply-To: <1117D087-AD76-4A87-8798-AB5526BECF3A@odin-corporation.com>
References:  <1117D087-AD76-4A87-8798-AB5526BECF3A@odin-corporation.com>

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On Sunday, March 29, 2015 02:29:42 PM Lars wrote:
> Hi,
> I am poking around for a cause for my repeating deadlock issues on my=
 system based on r 279869. ddb show witness show the =E2=80=9Cvnode int=
erlock=E2=80=9D and the =E2=80=9Czfs=E2=80=9D locks both with reference=
 counts over 200K. Obviously they are related, and there is a find runn=
ing (all the filesystems on this machine are zfs ( minus the specialty =
ones like devfs).
>=20
> I don=E2=80=99t see any other withness entry with reference counts ev=
en in the ballpark of these two, so does this indicate that we have a v=
node/zfs path were we don=E2=80=99t unlock?

The ref count just means that the locks exist (so you have 200k ZFS vno=
des),
not that the locks are currently held.  The reference count on the witn=
ess
object is bumped when a lock is created that uses that witness object a=
nd
released when the lock is destroyed.

--=20
John Baldwin



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