From: Jens Axboe <axboe@kernel.dk>
Date: Tue, 24 Jan 2023 08:24:25 -0700
Subject: [PATCH] io_uring: handle TIF_NOTIFY_RESUME when checking for
 task_work
References: bsc#1012628
Patch-mainline: 6.2.3
Git-commit: b5d3ae202fbfe055aa2a8ae8524531ee1dcab717

commit b5d3ae202fbfe055aa2a8ae8524531ee1dcab717 upstream.

If TIF_NOTIFY_RESUME is set, then we need to call resume_user_mode_work()
for PF_IO_WORKER threads. They never return to usermode, hence never get
a chance to process any items that are marked by this flag. Most notably
this includes the final put of files, but also any throttling markers set
by block cgroups.

Cc: stable@vger.kernel.org # 5.10+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 io_uring/io_uring.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index ab4b2a1c..e532dea6 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -3,6 +3,7 @@
 
 #include <linux/errno.h>
 #include <linux/lockdep.h>
+#include <linux/resume_user_mode.h>
 #include <linux/io_uring_types.h>
 #include <uapi/linux/eventpoll.h>
 #include "io-wq.h"
@@ -270,6 +271,13 @@ static inline int io_run_task_work(void)
 	 */
 	if (test_thread_flag(TIF_NOTIFY_SIGNAL))
 		clear_notify_signal();
+	/*
+	 * PF_IO_WORKER never returns to userspace, so check here if we have
+	 * notify work that needs processing.
+	 */
+	if (current->flags & PF_IO_WORKER &&
+	    test_thread_flag(TIF_NOTIFY_RESUME))
+		resume_user_mode_work(NULL);
 	if (task_work_pending(current)) {
 		__set_current_state(TASK_RUNNING);
 		task_work_run();
-- 
2.35.3