From: Stephen Hemminger <stephen@networkplumber.org>
To: Cong Wang <cwang@twopensource.com>
Cc: Dominick Grift <dac.override@gmail.com>, netdev <netdev@vger.kernel.org>
Subject: Re: Suspicious RCU usage in bridge with Linux v4.0-9362-g1fc149933fd4
Date: Mon, 4 May 2015 13:27:14 -0700 [thread overview]
Message-ID: <20150504132714.55dca5b0@urahara> (raw)
In-Reply-To: <CAHA+R7PAzzz+CZfnOoweBdeLY8tRkr2bSDEpQgdtEKUeaZbWpQ@mail.gmail.com>
On Mon, 4 May 2015 11:45:41 -0700
Cong Wang <cwang@twopensource.com> wrote:
> On Mon, May 4, 2015 at 6:39 AM, Dominick Grift <dac.override@gmail.com> wrote:
> > On Thu, Apr 23, 2015 at 01:07:45PM -0400, Josh Boyer wrote:
> >> Hi All,
> >>
> >> We've had a user report the following backtrace from the bridge module
> >> with a recent Linus' tree. Has anything like this been reported yet?
> >> If you have any questions on setup, the user is CC'd.
> >>
> >> josh
> >>
> >> [ 29.382235] br0: port 1(tap0) entered forwarding state
> >>
> >> [ 29.382286] ===============================
> >> [ 29.382315] [ INFO: suspicious RCU usage. ]
> >> [ 29.382344] 4.1.0-0.rc0.git11.1.fc23.x86_64 #1 Not tainted
> >> [ 29.382380] -------------------------------
> >> [ 29.382409] net/bridge/br_private.h:626 suspicious
> >> rcu_dereference_check() usage!
> >
> > <snip>
> >
> > With 4.1.0-0.rc1.git1.1.fc23.x86_64 the situation seems to have slightly changed:
> >
>
> Should be the same issue. Please give the attached patch a try,
> it is compile-tested only.
>
> Thanks!
Good analysis in identifying the issue. But the proposed patch
doesn't seem right.
The br->lock protects against changes to the bridge port state.
vlan_info should be treated as part of the bridge state.
The correct fix is to get vlan_info out of depending on RTNL
and use br->lock to control modifications.
next prev parent reply other threads:[~2015-05-04 20:27 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-23 17:07 Suspicious RCU usage in bridge with Linux v4.0-9362-g1fc149933fd4 Josh Boyer
2015-04-23 17:35 ` Sudeep Holla
2015-04-23 22:53 ` Cong Wang
2015-05-04 13:39 ` Dominick Grift
2015-05-04 18:45 ` Cong Wang
2015-05-04 20:27 ` Stephen Hemminger [this message]
2015-05-04 21:35 ` Cong Wang
2015-05-11 13:15 ` Dominick Grift
2015-05-11 14:53 ` Eric Dumazet
2015-05-11 17:42 ` Dominick Grift
2015-05-12 0:13 ` poma
2015-05-12 0:37 ` Eric Dumazet
2015-05-12 1:33 ` poma
2015-05-12 18:27 ` Dominick Grift
2015-05-21 19:22 ` Josh Boyer
2015-05-21 20:06 ` Eric Dumazet
2015-05-05 2:32 ` Vlad Yasevich
2015-05-04 20:49 ` Eric Dumazet
2015-05-04 21:38 ` Cong Wang
2015-05-04 22:06 ` Eric Dumazet
2015-05-04 22:17 ` Cong Wang
2015-05-04 22:29 ` Eric Dumazet
2015-05-04 22:44 ` Cong Wang
2015-05-04 23:00 ` Eric Dumazet
2015-05-04 23:22 ` David Miller
2015-05-05 8:33 ` Dominick Grift
2015-05-21 20:28 ` [PATCH net] bridge: fix lockdep splat Eric Dumazet
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