From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-2998-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [66.179.20.138]) by lists.oasis-open.org (Postfix) with ESMTP id CCD5C1CB8080 for ; Thu, 18 Jan 2018 22:21:56 -0800 (PST) Message-ID: <5A618F0B.4090805@intel.com> Date: Fri, 19 Jan 2018 14:24:11 +0800 From: Wei Wang MIME-Version: 1.0 References: <1516165812-3995-1-git-send-email-wei.w.wang@intel.com> <1516165812-3995-3-git-send-email-wei.w.wang@intel.com> <20180117180337-mutt-send-email-mst@kernel.org> In-Reply-To: <20180117180337-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: [virtio-dev] Re: [PATCH v22 2/3] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_VQ To: "Michael S. Tsirkin" Cc: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, akpm@linux-foundation.org, pbonzini@redhat.com, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com List-ID: On 01/18/2018 12:44 AM, Michael S. Tsirkin wrote: > On Wed, Jan 17, 2018 at 01:10:11PM +0800, Wei Wang wrote: >> >> +static void virtballoon_changed(struct virtio_device *vdev) >> +{ >> + struct virtio_balloon *vb = vdev->priv; >> + unsigned long flags; >> + __u32 cmd_id; >> + s64 diff = towards_target(vb); >> + >> + if (diff) { >> + spin_lock_irqsave(&vb->stop_update_lock, flags); >> + if (!vb->stop_update) > Why do you ignore stop_update for freeze? > This means new wq entries can be added during remove > causing use after free issues. I think stop_update isn't needed, because the lock has already been handled internally by the APIs. Similar examples like mem_cgroup_css_free() in "mm/memcontrol.c", there is no such locks used for cancel_work_sync(&memcg->high_work). Best, Wei --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org