From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751881AbdKFITL (ORCPT ); Mon, 6 Nov 2017 03:19:11 -0500 Received: from mga09.intel.com ([134.134.136.24]:4547 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750737AbdKFITK (ORCPT ); Mon, 6 Nov 2017 03:19:10 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.44,351,1505804400"; d="scan'208";a="1240188364" Message-ID: <5A001B72.1010204@intel.com> Date: Mon, 06 Nov 2017 16:21:06 +0800 From: Wei Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Tetsuo Handa , virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mst@redhat.com, mhocko@kernel.org, akpm@linux-foundation.org, mawilcox@microsoft.com CC: david@redhat.com, cornelia.huck@de.ibm.com, mgorman@techsingularity.net, aarcange@redhat.com, amit.shah@redhat.com, pbonzini@redhat.com, willy@infradead.org, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu@aliyun.com Subject: Re: [PATCH v17 4/6] virtio-balloon: VIRTIO_BALLOON_F_SG References: <1509696786-1597-1-git-send-email-wei.w.wang@intel.com> <1509696786-1597-5-git-send-email-wei.w.wang@intel.com> <201711032025.HJC78622.SFFOMLOtFQHVJO@I-love.SAKURA.ne.jp> <59FD9FE3.5090409@intel.com> <201711042028.EGB64074.FOLMHtFJVQOOFS@I-love.SAKURA.ne.jp> In-Reply-To: <201711042028.EGB64074.FOLMHtFJVQOOFS@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/04/2017 07:28 PM, Tetsuo Handa wrote: > Wei Wang wrote: >> On 11/03/2017 07:25 PM, Tetsuo Handa wrote: >> >> If this is inside vb->balloon_lock mutex (isn't this?), xb_set_page() must not >> use __GFP_DIRECT_RECLAIM allocation, for leak_balloon_sg_oom() will be blocked >> on vb->balloon_lock mutex. >> OK. Since the preload() doesn't need too much memory (< 4K in total), >> how about GFP_NOWAIT here? > Maybe GFP_NOWAIT | __GFP_NOWARN ? Sounds good to me. I also plan to move "xb_set_page()" under mutex_lock, that is, fill_balloon() { ... mutex_lock(&vb->balloon_lock); vb->num_pfns = 0; while ((page = balloon_page_pop(&pages))) { ==> xb_set_page(..,page,..); balloon_page_enqueue(&vb->vb_dev_info, page); ... } As explained in the xbitmap patch, we need the lock to avoid concurrent access to the bitmap. Best, Wei