From c7d95613c7d6e003969722a290397b8271bdad17 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Tue, 13 Apr 2021 11:43:00 +0100
Subject: [PATCH] io_uring: fix early sqd_list removal sqpoll hangs
[ 245.463317] INFO: task iou-sqp-1374:1377 blocked for more than 122 seconds.
[ 245.463334] task:iou-sqp-1374 state:D flags:0x00004000
[ 245.463345] Call Trace:
[ 245.463352] __schedule+0x36b/0x950
[ 245.463376] schedule+0x68/0xe0
[ 245.463385] __io_uring_cancel+0xfb/0x1a0
[ 245.463407] do_exit+0xc0/0xb40
[ 245.463423] io_sq_thread+0x49b/0x710
[ 245.463445] ret_from_fork+0x22/0x30
It happens when sqpoll forgot to run park_task_work and goes to exit,
then exiting user may remove ctx from sqd_list, and so corresponding
io_sq_thread() -> io_uring_cancel_sqpoll() won't be executed. Hopefully
it just stucks in do_exit() in this case.
Fixes: dbe1bdbb39db ("io_uring: handle signals for IO threads like a normal thread")
Reported-by: Joakim Hassila <joj@mac.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
fs/io_uring.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index bd14327c8e7e..dff34975d86b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6754,6 +6754,9 @@ static int io_sq_thread(void *data)
current->flags |= PF_NO_SETAFFINITY;
mutex_lock(&sqd->lock);
+ /* a user may had exited before the thread started */
+ io_run_task_work_head(&sqd->park_task_work);
+
while (!test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state)) {
int ret;
bool cap_entries, sqt_spin, needs_sched;
@@ -6770,10 +6773,10 @@ static int io_sq_thread(void *data)
}
cond_resched();
mutex_lock(&sqd->lock);
- if (did_sig)
- break;
io_run_task_work();
io_run_task_work_head(&sqd->park_task_work);
+ if (did_sig)
+ break;
timeout = jiffies + sqd->sq_thread_idle;
continue;
}