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Date:   Tue, 25 Jun 2019 19:02:20 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        "Pierre-Loup A. Griffais" <pgriffais@valvesoftware.com>,
        Eric Dumazet <edumazet@google.com>,
        lkml <linux-kernel@vger.kernel.org>
Subject: Re: Steam is broken on new kernels
Message-ID: <20190626020220.GA22548@roeck-us.net>
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Hi Greg,

On Sat, Jun 22, 2019 at 09:37:53AM +0200, Greg Kroah-Hartman wrote:
> On Fri, Jun 21, 2019 at 10:28:21PM -0700, Linus Torvalds wrote:
> > On Fri, Jun 21, 2019 at 6:03 PM Pierre-Loup A. Griffais
> > <pgriffais@valvesoftware.com> wrote:
> > >
> > > I applied Eric's path to the tip of the branch and ran that kernel and
> > > the bug didn't occur through several logout / login cycles, so things
> > > look good at first glance. I'll keep running that kernel and report back
> > > if anything crops up in the future, but I believe we're good, beyond
> > > getting distros to ship this additional fix.
> > 
> > Good. It's now in my tree, so we can get it quickly into stable and
> > then quickly to distributions.
> > 
> > Greg, it's commit b6653b3629e5 ("tcp: refine memory limit test in
> > tcp_fragment()"), and I'm building it right now and I'll push it out
> > in a couple of minutes assuming nothing odd is going on.
> 
> This looks good for 4.19 and 5.1, so I'll push out new stable kernels in
> a bit for them.
> 
> But for 4.14 and older, we don't have the "hint" to know this is an
> outbound going packet and not to apply these checks at that point in
> time, so this patch doesn't work.
> 
> I'll see if I can figure anything else later this afternoon for those
> kernels...
> 

I may have missed it, but I don't see a fix for the problem in
older stable branches. Any news ?

One possibility might be be to apply the part of 75c119afe14f7 which
introduces TCP_FRAG_IN_WRITE_QUEUE and TCP_FRAG_IN_RTX_QUEUE, if that
is acceptable.

Thanks,
Guenter