On 6/22/21 7:55 PM, Olivier Langlois wrote:
> If an asynchronous completion happens before the task is preparing
> itself to wait and set its state to TASK_INTERRUPTIBLE, the completion
> will not wake up the sqp thread.
>
> Signed-off-by: Olivier Langlois <olivier@xxxxxxxxxxxxxx>
> ---
> fs/io_uring.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index fc8637f591a6..02f789e07d4c 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -6902,7 +6902,7 @@ static int io_sq_thread(void *data)
> }
>
> prepare_to_wait(&sqd->wait, &wait, TASK_INTERRUPTIBLE);
> - if (!io_sqd_events_pending(sqd)) {
> + if (!io_sqd_events_pending(sqd) && !current->task_works) {
Agree that it should be here, but we also lack a good enough
task_work_run() around, and that may send the task burn CPU
for a while in some cases. Let's do
if (!io_sqd_events_pending(sqd) && !io_run_task_work())
...
fwiw, no need to worry about TASK_INTERRUPTIBLE as
io_run_task_work() sets it to TASK_RUNNING.
> needs_sched = true;
> list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
> io_ring_set_wakeup_flag(ctx);
>
--
Pavel Begunkov
