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Date:   Tue, 3 Dec 2019 20:14:28 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Mikulas Patocka <mpatocka@redhat.com>
Cc:     Mike Kravetz <mike.kravetz@oracle.com>,
        Daniel Axtens <dja@axtens.net>,
        Michael Neuling <mikey@neuling.org>,
        Peter Hurley <peter@hurleysoftware.com>,
        Jiri Slaby <jslaby@suse.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: tty crash in Linux 4.6
Message-ID: <20191203191428.GB2734645@kroah.com>
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On Tue, Dec 03, 2019 at 10:17:08AM -0500, Mikulas Patocka wrote:
> 
> 
> On Sat, 16 Nov 2019, Greg Kroah-Hartman wrote:
> 
> > On Fri, Nov 15, 2019 at 11:21:08AM -0800, Mike Kravetz wrote:
> > > On 4/11/18 9:09 AM, Daniel Axtens wrote:
> > > > Mikulas Patocka <mpatocka@redhat.com> writes:
> > > > 
> > > >> On Thu, 22 Mar 2018, Greg Kroah-Hartman wrote:
> > > >>
> > > >>> On Fri, Mar 23, 2018 at 12:48:06AM +1100, Daniel Axtens wrote:
> > > >>>> Hi,
> > > >>>>
> > > >>>>>> This patch works, I've had no tty crashes since applying it.
> > > >>>>>>
> > > >>>>>> I've seen that you haven't sent this patch yet to Linux-4.7-rc and
> > > >>>>>> Linux-4.6-stable. Will you? Or did you create a different patch?
> > > >>>>>
> > > >>>>> We are hitting this now on powerpc.  This patch never seemed to make
> > > >>>>> it upstream (drivers/tty/tty_ldisc.c hasn't been touched in 1 year).
> > > >>>>
> > > >>>> I seem to be hitting this too on a kernel that has the 4.6 changes
> > > >>>> backported to 4.4.
> > > >>>>
> > > >>>> Has there been any further progress on getting this accepted?
> > > >>>
> > > >>> Can you try applying 28b0f8a6962a ("tty: make n_tty_read() always abort
> > > >>> if hangup is in progress") to see if that helps out or not?
> > > > 
> > > > Sorry for the delay in getting the test results; as with Mikulas,
> > > > 28b0f8a6962a does not help.
> > > > 
> > > > Regards,
> > > > Daniel
> > > > 
> > > >>>
> > > >>> thanks,
> > > >>>
> > > >>> greg k-h
> > > >>
> > > >> It doesn't help. I get the same crash as before.
> > > >>
> > > >> Mikulas
> > > 
> > > Reviving a really old thread.
> > > 
> > > It looks like this patch never got merged.
> > 
> > I do not see a patch in this email, so I have no idea what you are
> > referring to, sorry.
> > 
> > > Did it get resolved in some other way?  I ask because we have a
> > > customer who seems to have hit this issue.
> > 
> > Can you try with the latest kernel to see if it is resolved or not?
> 
> I tested it on the kernel 5.4 and I couldn't reproduce the crash anymore.

Wonderful, please use that kernel then :)

thanks,

greg k-h