From owner-freebsd-fs  Mon Mar 18 15:41:13 2002
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Date: Mon, 18 Mar 2002 15:40:42 -0800
From: Kris Kennaway <kris@obsecurity.org>
To: Alfred Perlstein <alfred@freebsd.org>
Cc: Dag-Erling Smorgrav <des@ofug.org>,
	Kris Kennaway <kris@obsecurity.org>, current@freebsd.org,
	fs@freebsd.org
Subject: Re: panic: bwrite: buffer is not busy???
Message-ID: <20020318154041.B71020@xor.obsecurity.org>
References: <20020317124958.A34008@xor.obsecurity.org> <xzpadt6r1xr.fsf@flood.ping.uio.no> <20020318061739.GB894@elvis.mu.org> <xzpvgbupdqa.fsf@flood.ping.uio.no> <20020318071623.GD894@elvis.mu.org> <20020318010245.A48956@xor.obsecurity.org> <xzp4rjep7m5.fsf@flood.ping.uio.no> <20020318143204.GA688@elvis.mu.org> <xzplmcpn8un.fsf@flood.ping.uio.no> <20020318223631.GA23014@elvis.mu.org>
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In-Reply-To: <20020318223631.GA23014@elvis.mu.org>; from alfred@freebsd.org on Mon, Mar 18, 2002 at 02:36:31PM -0800
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On Mon, Mar 18, 2002 at 02:36:31PM -0800, Alfred Perlstein wrote:
> * Dag-Erling Smorgrav <des@ofug.org> [020318 08:23] wrote:
> > Alfred Perlstein <alfred@freebsd.org> writes:
> > > I think you're right, I'm pretty sure the fix is basically moving
> > > the p->p_fd =3D NULL to after the closef will fix things [...]
> >=20
> > There will still be a race...
>=20
> Are you sure? :)
>=20
> Btw, is there a way to easily reproduce this bug?

The panic in tail was triggered by using -f (i.e. kqueue), but it's
only happened once on the cluster..err..twice now (just happened
again).  Without your previous patch several cluster machines were
failing several times per hour, in umount.  You could probably trigger
it by stressing these two code paths.

I'll test your latest patch a bit later on.

Kris

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