FAILED: patch "[PATCH] io_uring: Fix race condition when sqp thread goes to sleep" failed to apply to 5.13-stable tree

From: <gregkh@linuxfoundation.org>
Date: 2021-07-11 18:04:25
Subsystem: filesystems (vfs and infrastructure), the rest · Maintainers: Alexander Viro, Christian Brauner, Linus Torvalds

The patch below does not apply to the 5.13-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 [off-list ref].

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 997135017716c33f3405e86cca5da9567b40a08e Mon Sep 17 00:00:00 2001
From: Olivier Langlois <redacted>
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@vger.kernel.org
Signed-off-by: Olivier Langlois <redacted>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d1419dc32ec6a97b453bee34dc03fa6a02797142.1624473200.git.olivier@trillion01.com (local)
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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);
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