From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 76C0F6B025F for ; Mon, 6 Nov 2017 03:19:11 -0500 (EST) Received: by mail-pf0-f199.google.com with SMTP id 76so10441359pfr.3 for ; Mon, 06 Nov 2017 00:19:11 -0800 (PST) Received: from mga09.intel.com (mga09.intel.com. [134.134.136.24]) by mx.google.com with ESMTPS id i13si10924122pgp.62.2017.11.06.00.19.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 06 Nov 2017 00:19:10 -0800 (PST) Message-ID: <5A001B72.1010204@intel.com> Date: Mon, 06 Nov 2017 16:21:06 +0800 From: Wei Wang MIME-Version: 1.0 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: owner-linux-mm@kvack.org List-ID: 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 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org