From: Stefano Garzarella sgarzare@redhat.com
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@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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);