FAILED: patch "[PATCH] io_uring: unpark SQPOLL thread for cancelation" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 34343786ecc5ff493ca4d1f873b4386759ba52ee Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <[email protected]>
Date: Wed, 10 Feb 2021 11:45:42 +0000
Subject: [PATCH] io_uring: unpark SQPOLL thread for cancelation

We park SQPOLL task before going into io_uring_cancel_files(), so the task won't run task_works including those that might be important for the cancellation passes. In this case it's io_poll_remove_one(), which frees requests via io_put_req_deferred().

Unpark it for while waiting, it's ok as we disable submissions beforehand, so no new requests will be generated.

INFO: task syz-executor893:8493 blocked for more than 143 seconds.
Call Trace:
 context_switch kernel/sched/core.c:4327 [inline]
 __schedule+0x90c/0x21a0 kernel/sched/core.c:5078
 schedule+0xcf/0x270 kernel/sched/core.c:5157
 io_uring_cancel_files fs/io_uring.c:8912 [inline]
 io_uring_cancel_task_requests+0xe70/0x11a0 fs/io_uring.c:8979
 __io_uring_files_cancel+0x110/0x1b0 fs/io_uring.c:9067
 io_uring_files_cancel include/linux/io_uring.h:51 [inline]
 do_exit+0x2fe/0x2ae0 kernel/exit.c:780
 do_group_exit+0x125/0x310 kernel/exit.c:922
 __do_sys_exit_group kernel/exit.c:933 [inline]
 __se_sys_exit_group kernel/exit.c:931 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:931
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

index 7a1e4ecf5f94..9ed79509f389 100644
@@ -9047,11 +9047,16 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx,
 			break;
 
 		io_uring_try_cancel_requests(ctx, task, files);
+
+		if (ctx->sq_data)
+			io_sq_thread_unpark(ctx->sq_data);
 		prepare_to_wait(&task->io_uring->wait, &wait,
 				TASK_UNINTERRUPTIBLE);
 		if (inflight == io_uring_count_inflight(ctx, task, files))
 			schedule();
 		finish_wait(&task->io_uring->wait, &wait);
+		if (ctx->sq_data)
+			io_sq_thread_park(ctx->sq_data);
 	}
 }