bug#34235: 0e334db6bb4b1fd1e2d72c1f3d8f004313cd9f94 (posix-timers: Fix division by zero bug). Problems with glibc.

[Thomas Gleixner <tglx@linutronix.de>]

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