From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 426AF2B9E; Tue, 28 Nov 2017 11:06:24 +0100 (CET) Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6EFA55D689; Tue, 28 Nov 2017 10:06:23 +0000 (UTC) Received: from [10.36.112.19] (ovpn-112-19.ams2.redhat.com [10.36.112.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 390A75191E; Tue, 28 Nov 2017 10:06:17 +0000 (UTC) To: dev@dpdk.org, yliu@fridaylinux.org, tiwei.bie@intel.com, jianfeng.tan@intel.com, vkaplans@redhat.com Cc: stable@dpdk.org, jfreiman@redhat.com References: <20171124180826.18439-1-maxime.coquelin@redhat.com> <20171124180826.18439-3-maxime.coquelin@redhat.com> From: Maxime Coquelin Message-ID: <06080f95-a65a-a449-1c47-72b9d4d53122@redhat.com> Date: Tue, 28 Nov 2017 11:06:15 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171124180826.18439-3-maxime.coquelin@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 28 Nov 2017 10:06:23 +0000 (UTC) Subject: Re: [dpdk-dev] [PATCH v2 2/3] vhost: protect dirty logging against logging base change X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 28 Nov 2017 10:06:24 -0000 On 11/24/2017 07:08 PM, Maxime Coquelin wrote: > When performing live-migration with multiple queue pairs, > VHOST_USER_SET_LOG_BASE request is sent multiple times. > > If packets are being processed by the PMD threads, it is > possible that they are setting bits in the dirty log map while > its region is being unmapped by the vhost-user protocol thread. > It results in the following crash: > Thread 3 "lcore-slave-2" received signal SIGSEGV, Segmentation fault. > [Switching to Thread 0x7f71ca495700 (LWP 32451)] > 0x00000000004bfc8a in vhost_set_bit (addr=0x7f71cbe18432 , nr=1) at /home/max/projects/src/mainline/dpdk/lib/librte_vhost/vhost.h:267 > 267 __sync_fetch_and_or_8(addr, (1U << nr)); > > We can see the vhost-user protocol thread just did the unmap of the > dirty log region when it happens. > > This patch prevents this by introducing a RW lock to protect > the log base. > > Fixes: 54f9e32305d4 ("vhost: handle dirty pages logging request") > Cc: stable@dpdk.org > > Signed-off-by: Maxime Coquelin > --- > lib/librte_vhost/vhost.c | 2 ++ > lib/librte_vhost/vhost.h | 14 +++++++++++--- > lib/librte_vhost/vhost_user.c | 4 ++++ > 3 files changed, 17 insertions(+), 3 deletions(-) > By clarifying the vhost-user spec, we may be able to avoid this lock and just ignore the subsequent SET_LOG_BASE requests once VHOST_F_LOG_ALL feature bit is set. So let's just discard this series for now. Maxime