From 19ec465786827a4da04ee0e6c3d20e7a16d5faaf Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 27 Jan 2023 09:50:31 -0700 Subject: [PATCH] io_uring: add reschedule point to handle_tw_list() BugLink: https://bugs.launchpad.net/bugs/2011425 commit f58680085478dd292435727210122960d38e8014 upstream. If CONFIG_PREEMPT_NONE is set and the task_work chains are long, we could be running into issues blocking others for too long. Add a reschedule check in handle_tw_list(), and flush the ctx if we need to reschedule. Cc: stable@vger.kernel.org # 5.10+ Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman Signed-off-by: Andrea Righi --- io_uring/io_uring.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index d7e2a7432d8a..80ba696e1c90 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -1143,10 +1143,16 @@ static unsigned int handle_tw_list(struct llist_node *node, /* if not contended, grab and improve batching */ *locked = mutex_trylock(&(*ctx)->uring_lock); percpu_ref_get(&(*ctx)->refs); - } + } else if (!*locked) + *locked = mutex_trylock(&(*ctx)->uring_lock); req->io_task_work.func(req, locked); node = next; count++; + if (unlikely(need_resched())) { + ctx_flush_and_put(*ctx, locked); + *ctx = NULL; + cond_resched(); + } } return count; -- 2.39.5