io_uring: break out of iowq iopoll on teardown

[ upstream commit 45500dc4e01c167ee063f3dcc22f51ced5b2b1e9 ] io-wq will retry iopoll even when it failed with -EAGAIN. If that races with task exit, which sets TIF_NOTIFY_SIGNAL for all its workers, such workers might potentially infinitely spin retrying iopoll again and again and each time failing on some allocation / waiting / etc. Don't keep spinning if io-wq is dying. Fixes: 561fb04 ("io_uring: replace workqueue usage with io-wq") Cc: [email protected] Signed-off-by: Pavel Begunkov <[email protected]> Signed-off-by: Jens Axboe <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
ixenion · Sep 19, 2023 · 9faa6d0 · 9faa6d0
1 parent 208858d
commit 9faa6d0
Show file tree

Hide file tree

Showing 3 changed files with 13 additions and 1 deletion.
diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c
@@ -176,6 +176,16 @@ static void io_worker_ref_put(struct io_wq *wq)
 		complete(&wq->worker_done);
 }
 
+bool io_wq_worker_stopped(void)
+{
+	struct io_worker *worker = current->pf_io_worker;
+
+	if (WARN_ON_ONCE(!io_wq_current_is_worker()))
+		return true;
+
+	return test_bit(IO_WQ_BIT_EXIT, &worker->wqe->wq->state);
+}
+
 static void io_worker_cancel_cb(struct io_worker *worker)
 {
 	struct io_wqe_acct *acct = io_wqe_get_acct(worker);

diff --git a/io_uring/io-wq.h b/io_uring/io-wq.h
@@ -129,6 +129,7 @@ void io_wq_hash_work(struct io_wq_work *work, void *val);
 
 int io_wq_cpu_affinity(struct io_wq *wq, cpumask_var_t mask);
 int io_wq_max_workers(struct io_wq *wq, int *new_count);
+bool io_wq_worker_stopped(void);
 
 static inline bool io_wq_is_hashed(struct io_wq_work *work)
 {

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
@@ -6898,7 +6898,8 @@ static void io_wq_submit_work(struct io_wq_work *work)
 			 */
 			if (ret != -EAGAIN || !(req->ctx->flags & IORING_SETUP_IOPOLL))
 				break;
-
+			if (io_wq_worker_stopped())
+				break;
 			/*
 			 * If REQ_F_NOWAIT is set, then don't wait or retry with
 			 * poll. -EAGAIN is final for that case.