linux-kernel - Re: RTNL: assertion failed at net/ipv6/addrconf.c (1699)

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Date:	Fri, 29 Aug 2014 21:53:39 +0200
From:	Sabrina Dubroca <sd@...asysnail.net>
To:	Cong Wang <cwang@...pensource.com>
Cc:	Tommi Rantala <tt.rantala@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	netdev <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>, trinity@...r.kernel.org,
	Dave Jones <davej@...hat.com>
Subject: Re: RTNL: assertion failed at net/ipv6/addrconf.c (1699)

2014-08-29, 11:14:48 -0700, Cong Wang wrote:
> On Fri, Aug 29, 2014 at 8:26 AM, Tommi Rantala <tt.rantala@...il.com> wrote:
> > [   77.297196] RTNL: assertion failed at net/ipv6/addrconf.c (1699)
> > [   77.298080] CPU: 0 PID: 4842 Comm: trinity-main Not tainted 3.17.0-rc2+ #30
> > [   77.299039] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> > [   77.299789]  ffff88003d76a618 ffff880026133c50 ffffffff8238ba79
> > ffff880037c84520
> > [   77.300829]  ffff880026133c90 ffffffff820bd52b 0000000000000000
> > ffffffff82d86c40
> > [   77.301869]  0000000000000000 00000000f76fd1e1 ffff8800382d8000
> > ffff8800382d8220
> > [   77.302906] Call Trace:
> > [   77.303246]  [<ffffffff8238ba79>] dump_stack+0x4d/0x66
> > [   77.303928]  [<ffffffff820bd52b>] addrconf_join_solict+0x4b/0xb0
> > [   77.304731]  [<ffffffff820b031b>] ipv6_dev_ac_inc+0x2bb/0x330
> > [   77.305498]  [<ffffffff820b0060>] ? ac6_seq_start+0x260/0x260
> > [   77.306257]  [<ffffffff820b05fe>] ipv6_sock_ac_join+0x26e/0x360
> > [   77.307046]  [<ffffffff820b0429>] ? ipv6_sock_ac_join+0x99/0x360
> > [   77.307798]  [<ffffffff820cdd60>] do_ipv6_setsockopt.isra.5+0xa70/0xf20
> 
> 
> I think we should just use rtnl_lock() instead of rcu_read_lock() there,
> it is not a hot path worth optimization.
> 
> Please try the attached patch.

note: it doesn't build as it is now, it needs:

-EXPORT_SYMBOL(dev_get_by_flags_rcu);
+EXPORT_SYMBOL(dev_get_by_flags);


I just tried your patch with a basic test program (open
socket/join/leave/close and open socket/join/close).

I think you need to modify ipv6_sock_ac_close as well, or you can still
trigger the assertion when closing the socket without leaving first.

Modified patch attached.


-- 
Sabrina

View attachment "ipv6-anycast_v2.diff" of type "text/plain" (4334 bytes)