From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: Fw: [Bug 54601] New: PPP regression on 3.2.39 stop work need
 restart server ont version 3.2.21 not found this problem.
Date: Mon, 04 Mar 2013 16:05:15 -0800
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References: <20130301084705.4169c429@nehalam.linuxnetplumber.net>
	 <20130304224837.GX9079@decadent.org.uk>
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Cc: Stephen Hemminger <stephen@networkplumber.org>,
	netdev@vger.kernel.org, micron10@gmail.com,
	Eric Dumazet <edumazet@google.com>
To: Ben Hutchings <ben@decadent.org.uk>
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On Mon, 2013-03-04 at 22:48 +0000, Ben Hutchings wrote:
> On Fri, Mar 01, 2013 at 08:47:05AM -0800, Stephen Hemminger wrote:
> > 
> > 
> > Begin forwarded message:
> > 
> > Date: Fri, 1 Mar 2013 01:24:14 -0800
> > From: "bugzilla-daemon@bugzilla.kernel.org" <bugzilla-daemon@bugzilla.kernel.org>
> > To: "stephen@networkplumber.org" <stephen@networkplumber.org>
> > Subject: [Bug 54601] New: PPP regression on 3.2.39 stop work need restart server ont version 3.2.21 not found this problem.
> > 
> > 
> > https://bugzilla.kernel.org/show_bug.cgi?id=54601
> > 
> >            Summary: PPP regression on 3.2.39 stop work need restart server
> >                     ont version 3.2.21 not found this problem.
> >            Product: Networking
> >            Version: 2.5
> >     Kernel Version: 3.2.39
> >           Platform: All
> >         OS/Version: Linux
> >               Tree: Mainline
> >             Status: NEW
> >           Severity: high
> >           Priority: P1
> >          Component: Other
> >         AssignedTo: shemminger@linux-foundation.org
> >         ReportedBy: micron10@gmail.com
> >         Regression: Yes
> > 
> > 
> > Hi
> > watch a problem with PPP after upgrade to version 3.2.39 ppp service stop work
> > 2 hours after start with this crash :
> > 
> > [79619.180026] unregister_netdevice: waiting for ppp618 to become free. Usage
> > count = 562
> [...]
> > [79862.540040] unregister_netdevice: waiting for ppp618 to become free. Usage
> > count = 30
> > [79872.680037] unregister_netdevice: waiting for ppp618 to become free. Usage
> > count = 9
> [...]
> 
> So there are many references left to the device, which slowly go away
> (very slowly, about 2 per second).  Maybe there are skbs in a queue somewhere
> that still refer to the PPP device.
> 
> Since this a regression between 3.2.21 and 3.2.29, it might have been
> introduced by:
> 
> commit 73a3346556281fd56f39f0a9475249e5039d8807
> Author: Eric Dumazet <edumazet@google.com>
> Date:   Thu Jun 14 06:42:44 2012 +0000
> 
>     net: remove skb_orphan_try()
>     
>     commit 62b1a8ab9b3660bb820d8dfe23148ed6cda38574 upstream.
> 
> But this is a bit of a guess.  And I don't think that this change
> would do more than expose/exacerbate a bug that already existed.
> 
> Ben.
> 

I wonder which component could possibly take one dev refcnt for every
packet.

maybe xdst_queue_output in net/xfrm/xfrm_policy.c ?

Then maybe the cleanup is not properly done at device dismantle