Re: FAILED: patch "[PATCH] posix-cpu-timers: Store a reference to a pid not a task" failed to apply to 5.6-stable tree

[Sasha Levin <sashal@kernel.org>]

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@linuxfoundation.org> 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@vger.kernel.org>.
>>
>>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,
Sasha