signal: don't allow STOP on PF_IO_WORKER threads

Just like we don't allow normal signals to IO threads, don't deliver a
STOP to a task that has PF_IO_WORKER set. The IO threads don't take
signals in general, and have no means of flushing out a stop either.

Longer term, we may want to look into allowing stop of these threads,
as it relates to eg process freezing. For now, this prevents a spin
issue if a SIGSTOP is delivered to the parent task.

Reported-by: Stefan Metzmacher <>
Signed-off-by: Jens Axboe <>
Signed-off-by: "Eric W. Biederman" <>
1 file changed