On Sat, Apr 18, 2020 at 01:38:41PM -0400, Sasha Levin wrote: > On Sat, Apr 18, 2020 at 12:05:13PM -0400, Sasha Levin wrote: > > On Sat, Apr 18, 2020 at 07:37:08AM -0500, Eric W. Biederman wrote: > > > <gregkh@xxxxxxxxxxxxxxxxxxx> writes: > > > > > > > The patch below does not apply to the 5.6-stable tree. > > > > If someone wants it applied there, or to any other stable or longterm > > > > tree, then please email the backport, including the original git commit > > > > id to <stable@xxxxxxxxxxxxxxx>. > > > > > > So for anyone who cares the fix I refer to in the commit comment is the > > > workaround that keeps the past implementation from being a real problem. > > > > > > I just see this as code cleanup so I can remove the old workaround. The > > > old workaround will cause posix_cpu_timers_exit_group to be called early > > > on particular variants of multi-threaded exec, resulting in the > > > corresponding cpu clock stopping. So this does represent a real fix. > > > > > > However using a cpu timer of another process to signal things in your > > > process is rare, and the case is breaks is only in certain obscure > > > variations of a multi-threaded exec. Further no one has to my knowledge > > > complained in over a decade. > > > > > > If someone sees that fix as important, and something that needs to be > > > backported, it will be easiest to backport my earlier cleanup patches > > > in the same series. > > > > For 5.6, 5.5, and 5.4 it was enough to take: > > > > 60f2ceaa8111 ("posix-cpu-timers: Remove unnecessary locking around cpu_clock_sample_group") > > > > as a dependency. Based on the commit message there it should be safe so > > I did just that. > > Ignore that, I've dropped it for now. THanks, I agree, this should just be left alone for now. greg k-h