On 2020-02-24 09:31:06 [-0600], Tom Zanussi wrote:

On Mon, 2020-02-24 at 10:43 +0100, Sebastian Andrzej Siewior wrote:

quoted

On 2020-02-21 15:24:43 [-0600], zanussi@kernel.org wrote:

quoted

From: Scott Wood <redacted>

v4.14.170-rt75-rc1 stable review patch.
If anyone has any objections, please let me know.

This creates bug which is stuffed later via
	sched: migrate_enable: Busy loop until the migration request is
completed

So if apply this, please take the bug fix, too. This is Stevens queue
for reference:

quoted

[PATCH RT 22/30] sched: migrate_enable: Use select_fallback_rq()

^^ bug introduced

Hmm, it seemed from the comment on the 4.19 series that it was '24/32
sched: migrate_enable: Use stop_one_cpu_nowait()' that required 'sched:
migrate_enable: Busy loop until the migration request is
completed' as a bug fix.

  https://lore.kernel.org/linux-rt-users/20200122083130.kuu3yppckhyjrr4u@linutronix.de/#t (local)

I didn't take the stop_one_cpu_nowait() one, so didn't take the busy
loop one either.

Ach, it was the different WARN_ON() then. So this might not introduce
any bug then. *Might*. 
Steven backported the whole pile and you took just this one patch. The
whole set was tested in devel and uncovered a problem which was fixed
later. Taking only a part *may* expose other problems it *may* be fine.

Steven, any opinion on your side?

Thanks,

Tom

Sebastian