From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: Kernel panic nf_nat_setup_info+0x5b3/0x6e0
Date: Thu, 31 Mar 2011 16:47:52 +0200
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Cc: Changli Gao <xiaosuo@gmail.com>, Patrick McHardy <kaber@trash.net>,
	netfilter-devel@vger.kernel.org, netdev@vger.kernel.org,
	Paul E McKenney <paulmck@linux.vnet.ibm.com>
To: "\"Oleg A. Arkhangelsky\"" <sysoleg@yandex.ru>
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Le jeudi 31 mars 2011 =C3=A0 18:03 +0400, "Oleg A. Arkhangelsky" a =C3=A9=
crit :
>=20
> 26.03.2011, 16:44, "Changli Gao" <xiaosuo@gmail.com>:
> > On Thu, Mar 3, 2011 at 3:33 PM, Changli Gao <xiaosuo@gmail.com>; wr=
ote:
> >
> >>  Please try the patch attached and test if the problem is solved o=
r not. Thanks.
> >
> > Any feedback? Thanks.
> >
>=20
> Seems that patch is fine.
>=20
> https://bugzilla.kernel.org/show_bug.cgi?id=3D21512
>=20

I wonder if this is not hiding another bug.

Adding an RCU grace period might reduce the probability window.

By the time nf_conntrack_free(ct) is called, no other cpu/thread
could/should use ct, or ct->ext ?

Sure, another thread can find/pass_on ct in a lookup but should not use
it, since its refcount (ct_general.use) should be 0.

Patrick ?