The patch below does not apply to the 5.17-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 stable@vger.kernel.org.

thanks,

greg k-h

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

From cce64ef01308b677a687d90927fc2b2e0e1cba67 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov asml.silence@gmail.com Date: Wed, 13 Apr 2022 16:10:34 +0100 Subject: [PATCH] io_uring: fix poll file assign deadlock

We pass "unlocked" into io_assign_file() in io_poll_check_events(), which can lead to double locking.

Fixes: 6bf9c47a3989 ("io_uring: defer file assignment") Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://lore.kernel.org/r/2476d4ae46554324b599ee4055447b105f20a75a.164986251... Signed-off-by: Jens Axboe axboe@kernel.dk

diff --git a/fs/io_uring.c b/fs/io_uring.c index 3d6cbf77c89d..d06f1952fdfa 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -5858,8 +5858,9 @@ static int io_poll_check_events(struct io_kiocb *req, bool locked)

if (!req->result) { struct poll_table_struct pt = { ._key = req->apoll_events }; + unsigned flags = locked ? 0 : IO_URING_F_UNLOCKED;

- if (unlikely(!io_assign_file(req, IO_URING_F_UNLOCKED))) + if (unlikely(!io_assign_file(req, flags))) req->result = -EBADF; else req->result = vfs_poll(req->file, &pt) & req->apoll_events;