io-wq: don't retry task_work creation failure on fatal conditions

io-wq: don't retry task_work creation failure on fatal conditions

BugLink: https://bugs.launchpad.net/bugs/1953731
[ Upstream commit a226abcd5d427fe9d42efc442818a4a1821e2664 ]

We don't want to be retrying task_work creation failure if there's
an actual signal pending for the parent task. If we do, then we can
enter an infinite loop of perpetually retrying and each retry failing
with -ERESTARTNOINTR because a signal is pending.

Fixes: 3146cba99aa2 ("io-wq: make worker creation resilient against signals")
Reported-by: Florian Fischer <florian.fl.fischer@fau.de>
Link: https://lore.kernel.org/io-uring/20211202165606.mqryio4yzubl7ms5@pasture/
Tested-by: Florian Fischer <florian.fl.fischer@fau.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>