The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 997135017716c33f3405e86cca5da9567b40a08e Mon Sep 17 00:00:00 2001 From: Olivier Langlois <olivier@xxxxxxxxxxxxxx> Date: Wed, 23 Jun 2021 11:50:11 -0700 Subject: [PATCH] io_uring: Fix race condition when sqp thread goes to sleep 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. Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Olivier Langlois <olivier@xxxxxxxxxxxxxx> Reviewed-by: Pavel Begunkov <asml.silence@xxxxxxxxx> Link: https://lore.kernel.org/r/d1419dc32ec6a97b453bee34dc03fa6a02797142.1624473200.git.olivier@xxxxxxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> diff --git a/fs/io_uring.c b/fs/io_uring.c index fc8637f591a6..7c545fa66f31 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) && !io_run_task_work()) { needs_sched = true; list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) { io_ring_set_wakeup_flag(ctx);