From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
Jens Axboe <axboe@kernel.dk>, Sasha Levin <sashal@kernel.org>,
io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH AUTOSEL 5.7 39/53] io_uring: fix io_sq_thread no schedule when busy
Date: Wed, 1 Jul 2020 21:21:48 -0400 [thread overview]
Message-ID: <20200702012202.2700645-39-sashal@kernel.org> (raw)
In-Reply-To: <20200702012202.2700645-1-sashal@kernel.org>
From: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
[ Upstream commit b772f07add1c0b22e02c0f1e96f647560679d3a9 ]
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: Sasha Levin <sashal@kernel.org>
---
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 1829be7f63a35..6cf9d509371e2 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6071,7 +6071,7 @@ 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
@@ -6087,7 +6087,7 @@ 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)
--
2.25.1
next parent reply other threads:[~2020-07-02 1:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200702012202.2700645-1-sashal@kernel.org>
2020-07-02 1:21 ` Sasha Levin [this message]
2020-07-02 1:21 ` [PATCH AUTOSEL 5.7 49/53] io_uring: fix current->mm NULL dereference on exit Sasha Levin
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