From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751196AbeAWJ1g (ORCPT ); Tue, 23 Jan 2018 04:27:36 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46456 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750946AbeAWJ1e (ORCPT ); Tue, 23 Jan 2018 04:27:34 -0500 From: Jason Wang To: mst@redhat.com, jasowang@redhat.com, linux-kernel@vger.kernel.org Cc: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH net 1/2] vhost: use mutex_lock_nested() in vhost_dev_lock_vqs() Date: Tue, 23 Jan 2018 17:27:25 +0800 Message-Id: <1516699646-7321-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- drivers/vhost/vhost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 33ac2b1..549771a 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -904,7 +904,7 @@ static void vhost_dev_lock_vqs(struct vhost_dev *d) { 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) -- 2.7.4