Patch "io_uring: don't save/restore iowait state" has been added to the 6.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    io_uring: don't save/restore iowait state

to the 6.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     io_uring-don-t-save-restore-iowait-state.patch
and it can be found in the queue-6.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 36ef14c43afb6b1766d4dfa13f566c266ef835ec
Author: Jens Axboe <axboe@xxxxxxxxx>
Date:   Mon Mar 11 13:30:43 2024 -0600

    io_uring: don't save/restore iowait state
    
    [ Upstream commit 6f0974eccbf78baead1735722c4f1ee3eb9422cd ]
    
    This kind of state is per-syscall, and since we're doing the waiting off
    entering the io_uring_enter(2) syscall, there's no way that iowait can
    already be set for this case. Simplify it by setting it if we need to,
    and always clearing it to 0 when done.
    
    Fixes: 7b72d661f1f2 ("io_uring: gate iowait schedule on having pending requests")
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 39dfb83dc9fc4..030cc930d1c6a 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2527,7 +2527,7 @@ static bool current_pending_io(void)
 static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
 					  struct io_wait_queue *iowq)
 {
-	int io_wait, ret;
+	int ret;
 
 	if (unlikely(READ_ONCE(ctx->check_cq)))
 		return 1;
@@ -2545,7 +2545,6 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
 	 * can take into account that the task is waiting for IO - turns out
 	 * to be important for low QD IO.
 	 */
-	io_wait = current->in_iowait;
 	if (current_pending_io())
 		current->in_iowait = 1;
 	ret = 0;
@@ -2553,7 +2552,7 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
 		schedule();
 	else if (!schedule_hrtimeout(&iowq->timeout, HRTIMER_MODE_ABS))
 		ret = -ETIME;
-	current->in_iowait = io_wait;
+	current->in_iowait = 0;
 	return ret;
 }