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Tsirkin" To: Yongji Xie Cc: Jason Wang , Stefan Hajnoczi , Stefano Garzarella , Parav Pandit , Christoph Hellwig , Christian Brauner , Randy Dunlap , Matthew Wilcox , viro@zeniv.linux.org.uk, Jens Axboe , bcrl@kvack.org, Jonathan Corbet , Mika =?iso-8859-1?Q?Penttil=E4?= , Dan Carpenter , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: Re: Re: [PATCH v6 03/10] vhost-vdpa: protect concurrent access to vhost device iotlb Message-ID: <20210412045900-mutt-send-email-mst@kernel.org> References: <20210331080519.172-1-xieyongji@bytedance.com> <20210331080519.172-4-xieyongji@bytedance.com> <20210409121512-mutt-send-email-mst@kernel.org> <20210411164827-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Apr 12, 2021 at 10:29:17AM +0800, Yongji Xie wrote: > On Mon, Apr 12, 2021 at 4:49 AM Michael S. Tsirkin wrote: > > > > On Sun, Apr 11, 2021 at 01:36:18PM +0800, Yongji Xie wrote: > > > On Sat, Apr 10, 2021 at 12:16 AM Michael S. Tsirkin wrote: > > > > > > > > On Wed, Mar 31, 2021 at 04:05:12PM +0800, Xie Yongji wrote: > > > > > Use vhost_dev->mutex to protect vhost device iotlb from > > > > > concurrent access. > > > > > > > > > > Fixes: 4c8cf318("vhost: introduce vDPA-based backend") > > > > > Cc: stable@vger.kernel.org > > > > > Signed-off-by: Xie Yongji > > > > > Acked-by: Jason Wang > > > > > Reviewed-by: Stefano Garzarella > > > > > > > > I could not figure out whether there's a bug there now. > > > > If yes when is the concurrent access triggered? > > > > > > > > > > When userspace sends the VHOST_IOTLB_MSG_V2 message concurrently? > > > > > > vhost_vdpa_chr_write_iter -> vhost_chr_write_iter -> > > > vhost_vdpa_process_iotlb_msg() > > > > > > Thanks, > > > Yongji > > > > And then what happens currently? > > > > Then we might access vhost_vdpa_map() concurrently and cause > corruption of the list and interval tree in struct vhost_iotlb. > > Thanks, > Yongji OK. Sounds like it's actually needed in this release if possible. Pls add this info in the commit log and post it as a separate patch. -- MST