Commit e22bc9b4 authored by Jens Axboe's avatar Jens Axboe
Browse files

kernel: make IO threads unfreezable by default 



The io-wq threads were already marked as no-freeze, but the manager was
not. On resume, we perpetually have signal_pending() being true, and
hence the manager will loop and spin 100% of the time.

Just mark the tasks created by create_io_thread() as PF_NOFREEZE by
default, and remove any knowledge of it in io-wq and io_uring.

Reported-by: default avatarKevin Locke <kevin@kevinlocke.name>
Tested-by: default avatarKevin Locke <kevin@kevinlocke.name>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e8f98f24

fs/io-wq.c

+1 −2
Original line number Diff line number Diff line
@@ -591,7 +591,7 @@ static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index) 
	tsk->pf_io_worker = worker;

	worker->task = tsk;

	set_cpus_allowed_ptr(tsk, cpumask_of_node(wqe->node));

	tsk->flags |= PF_NOFREEZE | PF_NO_SETAFFINITY;

	tsk->flags |= PF_NO_SETAFFINITY;



	raw_spin_lock_irq(&wqe->lock);

	hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
@@ -709,7 +709,6 @@ static int io_wq_manager(void *data) 
		set_current_state(TASK_INTERRUPTIBLE);

		io_wq_check_workers(wq);

		schedule_timeout(HZ);

		try_to_freeze();

		if (fatal_signal_pending(current))

			set_bit(IO_WQ_BIT_EXIT, &wq->state);

	} while (!test_bit(IO_WQ_BIT_EXIT, &wq->state));

fs/io_uring.c

+0 −1
Original line number Diff line number Diff line
@@ -6733,7 +6733,6 @@ static int io_sq_thread(void *data) 


			up_read(&sqd->rw_lock);

			schedule();

			try_to_freeze();

			down_read(&sqd->rw_lock);

			list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)

				io_ring_clear_wakeup_flag(ctx);

kernel/fork.c

+1 −0
Original line number Diff line number Diff line
@@ -2436,6 +2436,7 @@ struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node) 
	if (!IS_ERR(tsk)) {

		sigfillset(&tsk->blocked);

		sigdelsetmask(&tsk->blocked, sigmask(SIGKILL));

		tsk->flags |= PF_NOFREEZE;

	}

	return tsk;

}