Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 4 Feb 2019 17:25:11 +0000 (GMT)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Alan Mackenzie <acm@muc.de>
cc:     LKML <linux-kernel@vger.kernel.org>, 34235@debbugs.gnu.org,
        Eli Zaretskii <eliz@gnu.org>,
        Alex Branham <alex.branham@gmail.com>,
        Paul Eggert <eggert@cs.ucla.edu>,
        Greg KH <gregkh@linuxfoundation.org>
Subject: Re: 0e334db6bb4b1fd1e2d72c1f3d8f004313cd9f94 (posix-timers: Fix
 division by zero bug). Problems with glibc.
In-Reply-To: <20190202104404.GA1067@ACM>
Message-ID: <alpine.DEB.2.21.1902041724200.3006@nanos.tec.linutronix.de>
References: <20190201214700.GA4950@ACM> <alpine.DEB.2.21.1902012301310.8200@nanos.tec.linutronix.de> <20190202104404.GA1067@ACM>
User-Agent: Alpine 2.21 (DEB 202 2017-01-01)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sat, 2 Feb 2019, Alan Mackenzie wrote:
> Hello, Thomas.
> 
> Thanks for such a rapid reply!
> 
> On Fri, Feb 01, 2019 at 23:04:48 +0100, Thomas Gleixner wrote:
> > Hello Alan,
> 
> > On Fri, 1 Feb 2019, Alan Mackenzie wrote:
> > > 0e334db6bb4b1fd1e2d72c1f3d8f004313cd9f94
> > > posix-timers: Fix division by zero bug
> > > Committed: 2018-12-17 17:35:45 +0100
> 
> > > With this patch in place I am seeing problems with glibc's function
> > > timer_create.  I am an Emacs maintainer, and saw these problems whilst
> > > investigating Emacs bug #34235 "27.0.50; lisp profiler does not work".
> 
> > > Emacs's profiler fails in kernel 4.19.13, but works in a version of
> > > 4.19.13 with the patch reversed, otherwise unchanged.  My current version
> > > of glibc is 2.27-r6 (I think the "-r6" comes from Gentoo, my distro).
> 
> > Please upgrade to 4.19.19. The issue should be fixed there with the
> > backported variant of
> 
> >    93ad0fc088c5 ("posix-cpu-timers: Unbreak timer rearming")
> 
> > Commit 21c0d1621b8d4b in 4.19.19
> 
> I've just built and installed Linux 4.19.19, and it does indeed solve
> the Emacs profiler bug, #34235.  :-)
> 
> I see that the patch has been installed in 4.20.6, 4.19.19, and 4.14.97.
> Are there any plans to install it into 4.9.x, the other live long term
> support branch?  The reason I ask is to make an entry into Emacs's
> PROBLEMS file, telling users and distributions which kernel versions to
> upgrade to.

4.9 doesn't have the offending commit AFAICT.

Thanks,

	tglx