netdev - Re: Adding vlan to DSA port causes lockdep splat

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Date:   Wed, 29 Mar 2017 17:55:26 +0100
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Maxim Uvarov <muvarov@...il.com>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: Adding vlan to DSA port causes lockdep splat

On Wed, Mar 29, 2017 at 09:45:16AM -0700, Florian Fainelli wrote:
> On 02/21/2017 12:38 AM, Maxim Uvarov wrote:
> > Is there any progress on subj issue?

I'm afraid the report got completely ignored.  Hope you have better luck.

> > I see it was investigated here:
> > https://www.spinics.net/lists/netdev/msg361434.html
> 
> I was just able to reproduce this and will try to look into it. At first
> glance, the reason why we usually don't see it, is that VLAN
> configuration goes through bridge vlan, which exercises a slightly
> different code path.
> 
> FWIW: using bridge vlan (VLAN filtering) allows you to define your
> switch's default VLAN (ID and tag/untag flag) whereas the traditional
> vlan device does not really allow you to do that.
> 
> > 
> > But it still exist on later kernels:
> > 
> > [   37.320301] ip/1047 is trying to acquire lock:
> > [   37.324764]  (_xmit_ETHER/1){+.....}, at: [<c06ad228>] dev_mc_sync+0x4c/0x88
> > [   37.331882]
> > [   37.331882] but task is already holding lock:
> > [   37.337738]  (_xmit_ETHER/1){+.....}, at: [<c06ad228>] dev_mc_sync+0x4c/0x88
> > [   37.344828]
> > [   37.344828] other info that might help us debug this:
> > [   37.351384]  Possible unsafe locking scenario:
> > [   37.351384]
> > [   37.357326]        CPU0
> > [   37.359778]        ----
> > [   37.362230]   lock(_xmit_ETHER/1);
> > [   37.365650]   lock(_xmit_ETHER/1);
> > [   37.369069]
> > [   37.369069]  *** DEADLOCK ***
> > [   37.369069]
> > [   37.375013]  May be due to missing lock nesting notation
> > [   37.375013]
> > [   37.381830] 3 locks held by ip/1047:
> > [   37.385416]  #0:  (rtnl_mutex){+.+.+.}, at: [<c06b8248>]
> > rtnetlink_rcv+0x1c/0x38
> > [   37.392860]  #1:  (&vlan_netdev_addr_lock_key/1){+.....}, at:
> > [<c06a4f94>] dev_set_rx_mode+0x1c/0x30
> > [   37.402046]  #2:  (_xmit_ETHER/1){+.....}, at: [<c06ad228>]
> > dev_mc_sync+0x4c/0x88
> > [   37.409574]
> > [   37.409574] stack backtrace:
> > [   37.413952] CPU: 0 PID: 1047 Comm: ip Not tainted
> > 4.10.0maxdebug-00008-g9d55486 #22
> > [   37.421639] Hardware name: Generic AM33XX (Flattened Device Tree)
> > [   37.427756] Backtrace:
> > [   37.430237] [<c010bf78>] (dump_backtrace) from [<c010c220>]
> > (show_stack+0x18/0x1c)
> > [   37.437842]  r7:c140f7ec r6:c13e29e0 r5:dc316780 r4:c0db8408
> > [   37.443537] [<c010c208>] (show_stack) from [<c0402ab0>]
> > (dump_stack+0x20/0x28)
> > [   37.450800] [<c0402a90>] (dump_stack) from [<c016b294>]
> > (__lock_acquire+0x15d4/0x18ec)
> > [   37.458753] [<c0169cc0>] (__lock_acquire) from [<c016b958>]
> > (lock_acquire+0x74/0x94)
> > [   37.466532]  r10:dc2260c0 r9:dd747910 r8:00000000 r7:00000001
> > r6:00000001 r5:600d0013
> > [   37.474393]  r4:00000000
> > [   37.476946] [<c016b8e4>] (lock_acquire) from [<c07f802c>]
> > (_raw_spin_lock_nested+0x44/0x54)
> > [   37.485334]  r7:00001002 r6:dd4fd988 r5:dc1f3000 r4:dd4fd988
> > [   37.491022] [<c07f7fe8>] (_raw_spin_lock_nested) from [<c06ad228>]
> > (dev_mc_sync+0x4c/0x88)
> > [   37.499320]  r4:dd4fd800
> > [   37.501870] [<c06ad1dc>] (dev_mc_sync) from [<c0796b60>]
> > (dsa_slave_set_rx_mode+0x28/0x38)
> > [   37.510171]  r7:00001002 r6:00000000 r5:dd4fd800 r4:dc1f3000
> > [   37.515856] [<c0796b38>] (dsa_slave_set_rx_mode) from [<c06a4f40>]
> > (__dev_set_rx_mode+0x64/0x9c)
> > 
> 
> 
> -- 
> Florian

-- 
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