From: Stefano Garzarella <sgarzare@xxxxxxxxxx>
commit 7143b5ac5750f404ff3a594b34fdf3fc2f99f828 upstream.
This patch drops 'cur_mm' before calling cond_resched(), to prevent
the sq_thread from spinning even when the user process is finished.
Before this patch, if the user process ended without closing the
io_uring fd, the sq_thread continues to spin until the
'sq_thread_idle' timeout ends.
In the worst case where the 'sq_thread_idle' parameter is bigger than
INT_MAX, the sq_thread will spin forever.
Fixes: 6c271ce2f1d5 ("io_uring: add submission polling")
Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/io_uring.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2732,16 +2732,6 @@ static int io_sq_thread(void *data)
to_submit = io_sqring_entries(ctx);
if (!to_submit) {
/*
- * We're polling. If we're within the defined idle
- * period, then let us spin without work before going
- * to sleep.
- */
- if (inflight || !time_after(jiffies, timeout)) {
- cond_resched();
- continue;
- }
-
- /*
* Drop cur_mm before scheduling, we can't hold it for
* long periods (or over schedule()). Do this before
* adding ourselves to the waitqueue, as the unuse/drop
@@ -2753,6 +2743,16 @@ static int io_sq_thread(void *data)
cur_mm = NULL;
}
+ /*
+ * We're polling. If we're within the defined idle
+ * period, then let us spin without work before going
+ * to sleep.
+ */
+ if (inflight || !time_after(jiffies, timeout)) {
+ cond_resched();
+ continue;
+ }
+
prepare_to_wait(&ctx->sqo_wait, &wait,
TASK_INTERRUPTIBLE);
