Message-ID: <1451483700.8255.18.camel@edumazet-glaptop2.roam.corp.google.com>
Subject: Re: Linux 4.4-rc4 regression, bisected to "net: fix
 sock_wake_async() rcu protection"
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Nicolai Stange <nicstange@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>, Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 30 Dec 2015 08:55:00 -0500
In-Reply-To: <8760zgnpe0.fsf@gmail.com>
References: <CALCETrUHFDdfPymKfD2TJHL6w-C5dc675xuJfk=c=-twsPZqqA@mail.gmail.com>
	 <8760zgnpe0.fsf@gmail.com>
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On Wed, 2015-12-30 at 12:32 +0100, Nicolai Stange wrote:
> Andy Lutomirski <luto@kernel.org> writes:
> 
> > On recent v4.4-rc releases, I can't run emacs.  No, really, running
> > "emacs" in a GNOME 3 session makes gnome-shell think that emacs is
> > running, but no window is drawn, and the overall system UI is a bit
> > weird when the invisible emacs window is focused.
> >
> > This is 100% reproducible.
> >
> > There might be other symptoms involving gdb malfunctioning, but those
> > are, at best, sporadic.  The emacs failure is entirely reliable.  I
> > have no idea what the underlying failure mode is, but failure to wake
> > a socket waiter seems plausible,  I also have no idea why oocalc,
> > gimp, vim, gedit, firefox, etc aren't affected.
> >
> > A somewhat unorthodox "git bisect" run blames:
> >
> > commit ceb5d58b217098a657f3850b7a2640f995032e62
> > Author: Eric Dumazet <edumazet@google.com>
> > Date:   Sun Nov 29 20:03:11 2015 -0800
> >
> >     net: fix sock_wake_async() rcu protection
> >
> > I've confirmed that v4.4-rc7 with that patch reverted works fine.
> >
> > Since the offending commit was apparently a security fix, simply
> > reverting it might not be the best idea.
> 
> Please have a look at https://lkml.kernel.org/g/87ege73bma.fsf@gmail.com
> 
> I ran into the same issue and this one fixes it for me.

Right, and the ozlabs pointers for this were :

v1:
https://patchwork.ozlabs.org/patch/561194/

v2:
https://patchwork.ozlabs.org/patch/561553/

Thanks.


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