The patch below does not apply to the 5.15-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>.
Possible dependencies:
7cfe7a09489c ("io_uring: clear TIF_NOTIFY_SIGNAL if set and task_work not available")
46a525e199e4 ("io_uring: don't gate task_work run on TIF_NOTIFY_SIGNAL")
c0e0d6ba25f1 ("io_uring: add IORING_SETUP_DEFER_TASKRUN")
b4c98d59a787 ("io_uring: introduce io_has_work")
78a861b94959 ("io_uring: add sync cancelation API through io_uring_register()")
c34398a8c018 ("io_uring: remove __io_req_task_work_add")
ed5ccb3beeba ("io_uring: remove priority tw list optimisation")
625d38b3fd34 ("io_uring: improve io_run_task_work()")
4a0fef62788b ("io_uring: optimize io_uring_task layout")
253993210bd8 ("io_uring: introduce locking helpers for CQE posting")
305bef988708 ("io_uring: hide eventfd assumptions in eventfd paths")
affa87db9010 ("io_uring: fix multi ctx cancellation")
d9dee4302a7c ("io_uring: remove ->flush_cqes optimisation")
a830ffd28780 ("io_uring: move io_eventfd_signal()")
9046c6415be6 ("io_uring: reshuffle io_uring/io_uring.h")
d142c3ec8d16 ("io_uring: remove extra io_commit_cqring()")
68494a65d0e2 ("io_uring: introduce io_req_cqe_overflow()")
faf88dde060f ("io_uring: don't inline __io_get_cqe()")
d245bca6375b ("io_uring: don't expose io_fill_cqe_aux()")
9ca9fb24d5fe ("io_uring: mutex locked poll hashing")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 7cfe7a09489c1cefee7181e07b5f2bcbaebd9f41 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Fri, 25 Nov 2022 09:36:29 -0700
Subject: [PATCH] io_uring: clear TIF_NOTIFY_SIGNAL if set and task_work not
available
With how task_work is added and signaled, we can have TIF_NOTIFY_SIGNAL
set and no task_work pending as it got run in a previous loop. Treat
TIF_NOTIFY_SIGNAL like get_signal(), always clear it if set regardless
of whether or not task_work is pending to run.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 46a525e199e4 ("io_uring: don't gate task_work run on TIF_NOTIFY_SIGNAL")
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index cef5ff924e63..50bc3af44953 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -238,9 +238,14 @@ static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
static inline int io_run_task_work(void)
{
+ /*
+ * Always check-and-clear the task_work notification signal. With how
+ * signaling works for task_work, we can find it set with nothing to
+ * run. We need to clear it for that case, like get_signal() does.
+ */
+ if (test_thread_flag(TIF_NOTIFY_SIGNAL))
+ clear_notify_signal();
if (task_work_pending(current)) {
- if (test_thread_flag(TIF_NOTIFY_SIGNAL))
- clear_notify_signal();
__set_current_state(TASK_RUNNING);
task_work_run();
return 1;
