From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: Re: [PATCH v2 6/8] migration: move handle of zero page to the thread Date: Tue, 24 Jul 2018 15:39:00 +0800 Message-ID: <0647863e-dd2e-a761-9c3c-7a24b11a5f01@gmail.com> References: <20180719121520.30026-1-xiaoguangrong@tencent.com> <20180719121520.30026-7-xiaoguangrong@tencent.com> <20180723050325.GF2491@xz-mi> <20180723082838.GJ2491@xz-mi> <20180723094021.GN2491@xz-mi> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, mst@redhat.com, mtosatti@redhat.com, Xiao Guangrong , dgilbert@redhat.com, qemu-devel@nongnu.org, wei.w.wang@intel.com, jiang.biao2@zte.com.cn, pbonzini@redhat.com To: Peter Xu Return-path: In-Reply-To: <20180723094021.GN2491@xz-mi> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel2=m.gmane.org@nongnu.org Sender: "Qemu-devel" List-Id: kvm.vger.kernel.org On 07/23/2018 05:40 PM, Peter Xu wrote: > On Mon, Jul 23, 2018 at 04:44:49PM +0800, Xiao Guangrong wrote: > > [...] > >>>> >>>> However, it is not safe to do ram_release_pages in the thread as it's >>>> not protected it multithreads. Fortunately, compression will be disabled >>>> if it switches to post-copy, so i preferred to keep current behavior and >>>> deferred to fix it after this patchset has been merged. >>> >>> Do you mean ram_release_pages() is not thread-safe? Why? I didn't >>> notice it before but I feel like it is safe. >> >> bitmap_clear() called in the function is not safe. > > Yeah, and the funny thing is that I don't think ram_release_pages() > should even touch the receivedmap... It's possible that the > release-ram feature for postcopy is broken. > > Never mind on that. I'll post a patch to fix it, then I think the > ram_release_pages() will be thread safe. > > Then this patch shouldn't be affected and it should be fine after that > fix That would be great, thanks for your work.