From: Xuan Zhuo <[email protected]>
To: io-uring <[email protected]>
Cc: "[email protected]" <[email protected]>, [email protected]
Subject: [PATCH] io_uring: fix io_sq_thread no schedule when busy
Date: Mon, 22 Jun 2020 13:50:15 +0800 [thread overview]
Message-ID: <a932f437e5337cbfb42db660473fa55fa7aff9f6.1592805001.git.xuanzhuo@linux.alibaba.com> (raw)
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 adds a check after io_submit_sqes. If io_sq_thread does not call
cond_resched or schedule for more than HZ/2, it will call them.
Signed-off-by: Xuan Zhuo <[email protected]>
---
fs/io_uring.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index a78201b..de92363 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5983,7 +5983,7 @@ static int io_sq_thread(void *data)
struct io_ring_ctx *ctx = data;
const struct cred *old_cred;
DEFINE_WAIT(wait);
- unsigned long timeout;
+ unsigned long timeout, timeout_busy;
int ret = 0;
complete(&ctx->sq_thread_comp);
@@ -5991,6 +5991,7 @@ static int io_sq_thread(void *data)
old_cred = override_creds(ctx->creds);
timeout = jiffies + ctx->sq_thread_idle;
+ timeout_busy = jiffies + HZ/2;
while (!kthread_should_park()) {
unsigned int to_submit;
@@ -6012,6 +6013,7 @@ static int io_sq_thread(void *data)
* to enter the kernel to reap and flush events.
*/
if (!to_submit || ret == -EBUSY) {
+sched:
/*
* Drop cur_mm before scheduling, we can't hold it for
* long periods (or over schedule()). Do this before
@@ -6033,6 +6035,7 @@ static int io_sq_thread(void *data)
if (current->task_works)
task_work_run();
cond_resched();
+ timeout_busy = jiffies + HZ/2;
continue;
}
@@ -6073,6 +6076,8 @@ static int io_sq_thread(void *data)
schedule();
finish_wait(&ctx->sqo_wait, &wait);
+ timeout_busy = jiffies + HZ/2;
+
ctx->rings->sq_flags &= ~IORING_SQ_NEED_WAKEUP;
ret = 0;
continue;
@@ -6087,6 +6092,9 @@ static int io_sq_thread(void *data)
ret = io_submit_sqes(ctx, to_submit, NULL, -1);
mutex_unlock(&ctx->uring_lock);
timeout = jiffies + ctx->sq_thread_idle;
+
+ if (time_after(jiffies, timeout_busy))
+ goto sched;
}
if (current->task_works)
--
1.8.3.1
next reply other threads:[~2020-06-22 5:50 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-22 5:50 Xuan Zhuo [this message]
2020-06-22 14:43 ` [PATCH] io_uring: fix io_sq_thread no schedule when busy Jens Axboe
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