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[209.132.183.28]) by mx.google.com with ESMTPS id m9si39473941qke.19.2019.07.31.22.03.32 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 31 Jul 2019 22:03:32 -0700 (PDT) Received-SPF: pass (google.com: domain of jasowang@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of jasowang@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=jasowang@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D7CC330044CC; Thu, 1 Aug 2019 05:03:31 +0000 (UTC) Received: from [10.72.12.66] (ovpn-12-66.pek2.redhat.com [10.72.12.66]) by smtp.corp.redhat.com (Postfix) with ESMTP id 042175D9C9; Thu, 1 Aug 2019 05:03:25 +0000 (UTC) Subject: Re: [PATCH V2 4/9] vhost: reset invalidate_count in vhost_set_vring_num_addr() To: Jason Gunthorpe Cc: mst@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20190731084655.7024-1-jasowang@redhat.com> <20190731084655.7024-5-jasowang@redhat.com> <20190731124124.GD3946@ziepe.ca> <31ef9ed4-d74a-3454-a57d-fa843a3a802b@redhat.com> <20190731193252.GH3946@ziepe.ca> From: Jason Wang Message-ID: <0a4deb4e-92e8-44e1-b20e-05767641b6ba@redhat.com> Date: Thu, 1 Aug 2019 13:03:24 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190731193252.GH3946@ziepe.ca> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Thu, 01 Aug 2019 05:03:31 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2019/8/1 上午3:32, Jason Gunthorpe wrote: > On Wed, Jul 31, 2019 at 09:29:28PM +0800, Jason Wang wrote: >> On 2019/7/31 下午8:41, Jason Gunthorpe wrote: >>> On Wed, Jul 31, 2019 at 04:46:50AM -0400, Jason Wang wrote: >>>> The vhost_set_vring_num_addr() could be called in the middle of >>>> invalidate_range_start() and invalidate_range_end(). If we don't reset >>>> invalidate_count after the un-registering of MMU notifier, the >>>> invalidate_cont will run out of sync (e.g never reach zero). This will >>>> in fact disable the fast accessor path. Fixing by reset the count to >>>> zero. >>>> >>>> Reported-by: Michael S. Tsirkin >>> Did Michael report this as well? >> >> Correct me if I was wrong. I think it's point 4 described in >> https://lkml.org/lkml/2019/7/21/25. > I'm not sure what that is talking about > > But this fixes what I described: > > https://lkml.org/lkml/2019/7/22/554 > > Jason I'm sorry I miss this, will add your name as reported-by in the next version. Thanks