From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754276AbdJIPUr (ORCPT ); Mon, 9 Oct 2017 11:20:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42206 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751676AbdJIPUp (ORCPT ); Mon, 9 Oct 2017 11:20:45 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com E726C883DE Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=mst@redhat.com Date: Mon, 9 Oct 2017 18:20:30 +0300 From: "Michael S. Tsirkin" To: Wei Wang Cc: 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, mhocko@kernel.org, akpm@linux-foundation.org, mawilcox@microsoft.com, 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 v16 3/5] virtio-balloon: VIRTIO_BALLOON_F_SG Message-ID: <20171009181612-mutt-send-email-mst@kernel.org> References: <1506744354-20979-1-git-send-email-wei.w.wang@intel.com> <1506744354-20979-4-git-send-email-wei.w.wang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1506744354-20979-4-git-send-email-wei.w.wang@intel.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 09 Oct 2017 15:20:45 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 30, 2017 at 12:05:52PM +0800, Wei Wang wrote: > +static inline void xb_set_page(struct virtio_balloon *vb, > + struct page *page, > + unsigned long *pfn_min, > + unsigned long *pfn_max) > +{ > + unsigned long pfn = page_to_pfn(page); > + > + *pfn_min = min(pfn, *pfn_min); > + *pfn_max = max(pfn, *pfn_max); > + xb_preload(GFP_KERNEL); > + xb_set_bit(&vb->page_xb, pfn); > + xb_preload_end(); > +} > + So, this will allocate memory ... > @@ -198,9 +327,12 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) > struct page *page; > struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; > LIST_HEAD(pages); > + bool use_sg = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_SG); > + unsigned long pfn_max = 0, pfn_min = ULONG_MAX; > > - /* We can only do one array worth at a time. */ > - num = min(num, ARRAY_SIZE(vb->pfns)); > + /* Traditionally, we can only do one array worth at a time. */ > + if (!use_sg) > + num = min(num, ARRAY_SIZE(vb->pfns)); > > mutex_lock(&vb->balloon_lock); > /* We can't release more pages than taken */ And is sometimes called on OOM. I suspect we need to 1. keep around some memory for leak on oom 2. for non oom allocate outside locks -- MST