From: Ming Lei <[email protected]>
To: Jens Axboe <[email protected]>,
[email protected], [email protected]
Cc: David Howells <[email protected]>,
Chengming Zhou <[email protected]>,
Ming Lei <[email protected]>
Subject: [PATCH V2] io_uring: fix IO hang in io_wq_put_and_exit from do_exit()
Date: Fri, 1 Sep 2023 21:49:16 +0800 [thread overview]
Message-ID: <[email protected]> (raw)
io_wq_put_and_exit() is called from do_exit(), but all FIXED_FILE requests
in io_wq aren't canceled in io_uring_cancel_generic() called from do_exit().
Meantime io_wq IO code path may share resource with normal iopoll code
path.
So if any HIPRI request is submittd via io_wq, this request may not get resouce
for moving on, given iopoll isn't possible in io_wq_put_and_exit().
The issue can be triggered when terminating 't/io_uring -n4 /dev/nullb0'
with default null_blk parameters.
Fix it by always cancelling all requests in io_wq by adding helper of
io_uring_cancel_wq(), and this way is reasonable because io_wq destroying
follows canceling requests immediately.
Closes: https://lore.kernel.org/linux-block/[email protected]/
Reported-by: David Howells <[email protected]>
Cc: Chengming Zhou <[email protected]>,
Signed-off-by: Ming Lei <[email protected]>
---
V2:
- avoid to mess up io_uring_cancel_generic() by adding one new
helper for canceling io_wq requests
io_uring/io_uring.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index f4591b912ea8..7b3518f96c3b 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3298,6 +3298,37 @@ static s64 tctx_inflight(struct io_uring_task *tctx, bool tracked)
return percpu_counter_sum(&tctx->inflight);
}
+static void io_uring_cancel_wq(struct io_uring_task *tctx)
+{
+ int ret;
+
+ if (!tctx->io_wq)
+ return;
+
+ /*
+ * FIXED_FILE request isn't tracked in do_exit(), and these
+ * requests may be submitted to our io_wq as iopoll, so have to
+ * cancel them before destroying io_wq for avoiding IO hang
+ */
+ do {
+ struct io_tctx_node *node;
+ unsigned long index;
+
+ ret = 0;
+ xa_for_each(&tctx->xa, index, node) {
+ struct io_ring_ctx *ctx = node->ctx;
+ struct io_task_cancel cancel = { .task = current, .all = true, };
+ enum io_wq_cancel cret;
+
+ io_iopoll_try_reap_events(ctx);
+ cret = io_wq_cancel_cb(tctx->io_wq, io_cancel_task_cb,
+ &cancel, true);
+ ret |= (cret != IO_WQ_CANCEL_NOTFOUND);
+ cond_resched();
+ }
+ } while (ret);
+}
+
/*
* Find any io_uring ctx that this task has registered or done IO on, and cancel
* requests. @sqd should be not-null IFF it's an SQPOLL thread cancellation.
@@ -3369,6 +3400,7 @@ __cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
finish_wait(&tctx->wait, &wait);
} while (1);
+ io_uring_cancel_wq(tctx);
io_uring_clean_tctx(tctx);
if (cancel_all) {
/*
--
2.41.0
next reply other threads:[~2023-09-01 13:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-01 13:49 Ming Lei [this message]
2023-09-01 14:47 ` [PATCH V2] io_uring: fix IO hang in io_wq_put_and_exit from do_exit() Jens Axboe
2023-09-01 15:12 ` Ming Lei
2023-09-01 15:13 ` Jens Axboe
2023-09-01 15:13 ` Jens Axboe
2023-09-07 15:36 ` Jens Axboe
2023-09-08 1:03 ` Pavel Begunkov
2023-09-08 6:22 ` Ming Lei
2023-09-08 16:01 ` Pavel Begunkov
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