Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Thu, 3 Oct 2019 12:48:39 -0700
From:   Eric Biggers <ebiggers@kernel.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        syzbot+af05535bb79520f95431@syzkaller.appspotmail.com,
        syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com,
        Christoph Hellwig <hch@lst.de>,
        Miklos Szeredi <mszeredi@redhat.com>,
        Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 4.19 209/211] fuse: fix deadlock with aio poll and
 fuse_iqueue::waitq.lock
Message-ID: <20191003194838.GA6620@gmail.com>
Mail-Followup-To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        syzbot+af05535bb79520f95431@syzkaller.appspotmail.com,
        syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com,
        Christoph Hellwig <hch@lst.de>,
        Miklos Szeredi <mszeredi@redhat.com>,
        Sasha Levin <sashal@kernel.org>
References: <20191003154447.010950442@linuxfoundation.org>
 <20191003154530.645657617@linuxfoundation.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20191003154530.645657617@linuxfoundation.org>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Oct 03, 2019 at 05:54:35PM +0200, Greg Kroah-Hartman wrote:
>  
>  static void queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
>  {
> -	spin_lock(&fiq->waitq.lock);
> +	spin_lock(&fiq->lock);
>  	if (test_bit(FR_FINISHED, &req->flags)) {
> -		spin_unlock(&fiq->waitq.lock);
> +		spin_unlock(&fiq->lock);
>  		return;
>  	}
>  	if (list_empty(&req->intr_entry)) {
>  		list_add_tail(&req->intr_entry, &fiq->interrupts);
>  		wake_up_locked(&fiq->waitq);
>  	}
> -	spin_unlock(&fiq->waitq.lock);
> +	spin_unlock(&fiq->lock);
>  	kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
>  }

This isn't backported correctly.  wake_up_locked() needs to be changed to wake_up().

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index c0d59a86ada2e..6d39143cfa094 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -434,7 +434,7 @@ static void queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
 	}
 	if (list_empty(&req->intr_entry)) {
 		list_add_tail(&req->intr_entry, &fiq->interrupts);
-		wake_up_locked(&fiq->waitq);
+		wake_up(&fiq->waitq);
 	}
 	spin_unlock(&fiq->lock);
 	kill_fasync(&fiq->fasync, SIGIO, POLL_IN);