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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: Kevin Locke <kevin@kevinlocke.name>
Tested-by: Kevin Locke <kevin@kevinlocke.name>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2021-03-09 19:49:02 -07:00
parent e8f98f2454
commit e22bc9b481
3 changed files with 2 additions and 3 deletions
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3
fs/io-wq.c
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@ -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));

1
fs/io_uring.c
View File

@ -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);

1
kernel/fork.c
View File

@ -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;
}