The patch below does not apply to the 5.11-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 7c977a58dc83366e488c217fd88b1469d242bee5 Mon Sep 17 00:00:00 2001
From: Jens Axboe axboe@kernel.dk Date: Tue, 23 Feb 2021 19:17:35 -0700 Subject: [PATCH] io_uring: don't attempt IO reissue from the ring exit path
If we're exiting the ring, just let the IO fail with -EAGAIN as nobody will care anyway. It's not the right context to reissue from.
Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe axboe@kernel.dk
diff --git a/fs/io_uring.c b/fs/io_uring.c index bf9ad810c621..275ad84e8227 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2839,6 +2839,13 @@ static bool io_rw_reissue(struct io_kiocb *req) return false; if ((req->flags & REQ_F_NOWAIT) || io_wq_current_is_worker()) return false; + /* + * If ref is dying, we might be running poll reap from the exit work. + * Don't attempt to reissue from that path, just let it fail with + * -EAGAIN. + */ + if (percpu_ref_is_dying(&req->ctx->refs)) + return false;
lockdep_assert_held(&req->ctx->uring_lock);