io_uring: cancel pending async work if task exits

to #26323588

commit 6ab231448fdc5e37c15a94a4700fca11e80007f7 upstream.

Normally we cancel all work we track, but for untracked work we could
leave the async worker behind until that work completes. This is totally
fine, but does leave resources pending after the task is gone until that
work completes.

Cancel work that this task queued up when it goes away.
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>

fs/io_uring.c

@@ -925,6 +925,8 @@ static inline void io_req_work_grab_env(struct io_kiocb *req,
 		}
 		spin_unlock(&current->fs->lock);
 	}
+	if (!req->work.task_pid)
+		req->work.task_pid = task_pid_vnr(current);
 }
 
 static inline void io_req_work_drop_env(struct io_kiocb *req)
@@ -6462,6 +6464,13 @@ static int io_uring_flush(struct file *file, void *data)
 	struct io_ring_ctx *ctx = file->private_data;
 
 	io_uring_cancel_files(ctx, data);
+
+	/*
+	 * If the task is going away, cancel work it may have pending
+	 */
+	if (fatal_signal_pending(current) || (current->flags & PF_EXITING))
+		io_wq_cancel_pid(ctx->io_wq, task_pid_vnr(current));
+
 	return 0;
 }