From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by dpdk.org (Postfix) with ESMTP id F342C1B2C1; Wed, 14 Feb 2018 03:03:13 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Feb 2018 18:03:13 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,510,1511856000"; d="scan'208";a="19819355" Received: from tanjianf-mobl.ccr.corp.intel.com (HELO [10.255.26.58]) ([10.255.26.58]) by fmsmga002.fm.intel.com with ESMTP; 13 Feb 2018 18:03:11 -0800 To: Maxime Coquelin , dev@dpdk.org, yliu@fridaylinux.org, tiwei.bie@intel.com, vkaplans@redhat.com References: <20171124180826.18439-1-maxime.coquelin@redhat.com> <20171124180826.18439-3-maxime.coquelin@redhat.com> <06080f95-a65a-a449-1c47-72b9d4d53122@redhat.com> Cc: stable@dpdk.org, jfreiman@redhat.com From: "Tan, Jianfeng" Message-ID: <2bb2c3fa-597f-ad32-0b8e-0db6136d0a09@intel.com> Date: Wed, 14 Feb 2018 10:03:11 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <06080f95-a65a-a449-1c47-72b9d4d53122@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit 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: Wed, 14 Feb 2018 02:03:14 -0000 Hi Maxime, On 11/28/2017 6:06 PM, Maxime Coquelin wrote: > > > 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 > Cannot access memory at address 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. I would assume this issue has been addressed by the per-queue lock patch from Victor, correct? Besides, we really don't need multiple unmap/map for each vq. Would you think this shall be fixed in QEMU? Thanks, Jianfeng