Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:41442 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932515AbeBWSmQ (ORCPT ); Fri, 23 Feb 2018 13:42:16 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+dbb7c1161485e61b0241@syzkaller.appspotmail.com, Jason Wang , "Michael S. Tsirkin" , "David S. Miller" Subject: [PATCH 4.9 001/145] vhost: use mutex_lock_nested() in vhost_dev_lock_vqs() Date: Fri, 23 Feb 2018 19:25:07 +0100 Message-Id: <20180223170724.846027079@linuxfoundation.org> In-Reply-To: <20180223170724.669759283@linuxfoundation.org> References: <20180223170724.669759283@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Wang commit e9cb4239134c860e5f92c75bf5321bd377bb505b upstream. We used to call mutex_lock() in vhost_dev_lock_vqs() which tries to hold mutexes of all virtqueues. This may confuse lockdep to report a possible deadlock because of trying to hold locks belong to same class. Switch to use mutex_lock_nested() to avoid false positive. Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API") Reported-by: syzbot+dbb7c1161485e61b0241@syzkaller.appspotmail.com Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/vhost/vhost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -849,7 +849,7 @@ static void vhost_dev_lock_vqs(struct vh { int i = 0; for (i = 0; i < d->nvqs; ++i) - mutex_lock(&d->vqs[i]->mutex); + mutex_lock_nested(&d->vqs[i]->mutex, i); } static void vhost_dev_unlock_vqs(struct vhost_dev *d)