From: Xuan Zhuo xuanzhuo@linux.alibaba.com
mainline inclusion from mainline-5.8-rc3 commit b772f07add1c0b22e02c0f1e96f647560679d3a9 category: feature bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=27 CVE: NA ---------------------------
When the user consumes and generates sqe at a fast rate, io_sqring_entries can always get sqe, and ret will not be equal to -EBUSY, so that io_sq_thread will never call cond_resched or schedule, and then we will get the following system error prompt:
rcu: INFO: rcu_sched self-detected stall on CPU or watchdog: BUG: soft lockup-CPU#23 stuck for 112s! [io_uring-sq:1863]
This patch checks whether need to call cond_resched() by checking the need_resched() function every cycle.
Suggested-by: Jens Axboe axboe@kernel.dk Signed-off-by: Xuan Zhuo xuanzhuo@linux.alibaba.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: yangerkun yangerkun@huawei.com Reviewed-by: zhangyi (F) yi.zhang@huawei.com Signed-off-by: Cheng Jian cj.chengjian@huawei.com --- fs/io_uring.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 22b5e9cb7024..c8525c70cc77 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -5969,7 +5969,7 @@ static int io_sq_thread(void *data) * If submit got -EBUSY, flag us as needing the application * to enter the kernel to reap and flush events. */ - if (!to_submit || ret == -EBUSY) { + if (!to_submit || ret == -EBUSY || need_resched()) { /* * Drop cur_mm before scheduling, we can't hold it for * long periods (or over schedule()). Do this before @@ -5985,7 +5985,7 @@ static int io_sq_thread(void *data) * more IO, we should wait for the application to * reap events and wake us up. */ - if (!list_empty(&ctx->poll_list) || + if (!list_empty(&ctx->poll_list) || need_resched() || (!time_after(jiffies, timeout) && ret != -EBUSY && !percpu_ref_is_dying(&ctx->refs))) { if (current->task_works)