From: Jens Axboe <axboe@kernel.dk>
Date: Wed, 24 Feb 2021 02:17:35 +0000 (-0700)
Subject: io_uring: don't attempt IO reissue from the ring exit path
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=7c977a58dc83366e488c217fd88b1469d242bee5;p=linux.git

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 bf9ad810c6219..275ad84e8227b 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);