Thanks for helping to track down this bug. Since the problem occurs only
with a few Linux kernel versions and affects Emacs only when doing CPU
profiling, it doesn't seem worth spending time to try to patch Emacs to
work around the bug. So I installed the attached patch into emacs-26's
etc/PROBLEMS file to warn users about the problem, and am closing the
Emacs bug report.
On Fri, 1 Feb 2019, Paul Eggert wrote:
> Thanks for helping to track down this bug. Since the problem occurs only with
> a few Linux kernel versions and affects Emacs only when doing CPU profiling,
> it doesn't seem worth spending time to try to patch Emacs to work around the
> bug. So I installed the attached patch into emacs-26's etc/PROBLEMS file to
> warn users about the problem, and am closing the Emacs bug report.
Can you please verify whether the issue is fixed with 4.19.19? The commit
in question broke posix CPU timers as a unintended side effect and a follow
up patch unbreaks them again.
Thanks,
tglx
Thomas Gleixner wrote:
> Can you please verify whether the issue is fixed with 4.19.19?
It depends on what you mean by "verify". I looked at the Linux kernel source
code and checked that the "posix-cpu-timers: Unbreak timer rearming" patch is in
4.19.19 (but not 4.19.18) and in 4.20.6 (but not 4.20.5). I did not test Emacs's
CPU profiler on these kernels, as I don't have them installed. I expect to
upgrade soon to 4.20.6 (whenever Fedora 29 release does - 4.20.6 was submitted
for testing a couple of days ago) and plan to give it a try then.