From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F368FC32753 for ; Wed, 14 Aug 2019 10:30:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D44A42083B for ; Wed, 14 Aug 2019 10:30:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726221AbfHNKaJ (ORCPT ); Wed, 14 Aug 2019 06:30:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36274 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725800AbfHNKaJ (ORCPT ); Wed, 14 Aug 2019 06:30:09 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0EB3F30083EE; Wed, 14 Aug 2019 10:30:07 +0000 (UTC) Received: from gondolin (dhcp-192-232.str.redhat.com [10.33.192.232]) by smtp.corp.redhat.com (Postfix) with ESMTP id 59F6C1001B35; Wed, 14 Aug 2019 10:29:52 +0000 (UTC) Date: Wed, 14 Aug 2019 12:29:49 +0200 From: Cornelia Huck To: Nitesh Narayan Lal Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtio-dev@lists.oasis-open.org, pbonzini@redhat.com, lcapitulino@redhat.com, pagupta@redhat.com, wei.w.wang@intel.com, yang.zhang.wz@gmail.com, riel@surriel.com, david@redhat.com, mst@redhat.com, dodgen@google.com, konrad.wilk@oracle.com, dhildenb@redhat.com, aarcange@redhat.com, alexander.duyck@gmail.com, john.starks@microsoft.com, dave.hansen@intel.com, mhocko@suse.com Subject: Re: [RFC][Patch v12 2/2] virtio-balloon: interface to support free page reporting Message-ID: <20190814122949.4946f438.cohuck@redhat.com> In-Reply-To: <20190812131235.27244-3-nitesh@redhat.com> References: <20190812131235.27244-1-nitesh@redhat.com> <20190812131235.27244-3-nitesh@redhat.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Wed, 14 Aug 2019 10:30:09 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, 12 Aug 2019 09:12:35 -0400 Nitesh Narayan Lal wrote: > Enables the kernel to negotiate VIRTIO_BALLOON_F_REPORTING feature with > the host. If it is available and page_reporting_flag is set to true, > page_reporting is enabled and its callback is configured along with > the max_pages count which indicates the maximum number of pages that > can be isolated and reported at a time. Currently, only free pages of > order >= (MAX_ORDER - 2) are reported. To prevent any false OOM > max_pages count is set to 16. > > By default page_reporting feature is enabled and gets loaded as soon > as the virtio-balloon driver is loaded. However, it could be disabled > by writing the page_reporting_flag which is a virtio-balloon parameter. > > Signed-off-by: Nitesh Narayan Lal > --- > drivers/virtio/Kconfig | 1 + > drivers/virtio/virtio_balloon.c | 64 ++++++++++++++++++++++++++++- > include/uapi/linux/virtio_balloon.h | 1 + > 3 files changed, 65 insertions(+), 1 deletion(-) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 226fbb995fb0..defec00d4ee2 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c (...) > +static void virtballoon_page_reporting_setup(struct virtio_balloon *vb) > +{ > + struct device *dev = &vb->vdev->dev; > + int err; > + > + vb->page_reporting_conf.report = virtballoon_report_pages; > + vb->page_reporting_conf.max_pages = PAGE_REPORTING_MAX_PAGES; > + err = page_reporting_enable(&vb->page_reporting_conf); > + if (err < 0) { > + dev_err(dev, "Failed to enable reporting, err = %d\n", err); > + page_reporting_flag = false; Should we clear the feature bit in this case as well? > + vb->page_reporting_conf.report = NULL; > + vb->page_reporting_conf.max_pages = 0; > + return; > + } > +} > + > static void set_page_pfns(struct virtio_balloon *vb, > __virtio32 pfns[], struct page *page) > { > @@ -476,6 +524,7 @@ static int init_vqs(struct virtio_balloon *vb) > names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate"; > names[VIRTIO_BALLOON_VQ_STATS] = NULL; > names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; > + names[VIRTIO_BALLOON_VQ_REPORTING] = NULL; > > if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { > names[VIRTIO_BALLOON_VQ_STATS] = "stats"; > @@ -487,11 +536,18 @@ static int init_vqs(struct virtio_balloon *vb) > callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; > } > > + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) { > + names[VIRTIO_BALLOON_VQ_REPORTING] = "reporting_vq"; > + callbacks[VIRTIO_BALLOON_VQ_REPORTING] = balloon_ack; Do we even want to try to set up the reporting queue if reporting has been disabled via module parameter? Might make more sense to not even negotiate the feature bit in that case. > + } > err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, > vqs, callbacks, names, NULL, NULL); > if (err) > return err; > > + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) > + vb->reporting_vq = vqs[VIRTIO_BALLOON_VQ_REPORTING]; > + > vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE]; > vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE]; > if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { > @@ -924,6 +980,9 @@ static int virtballoon_probe(struct virtio_device *vdev) > if (err) > goto out_del_balloon_wq; > } > + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING) && > + page_reporting_flag) > + virtballoon_page_reporting_setup(vb); In that case, you'd only need to check for the feature bit here. > virtio_device_ready(vdev); > > if (towards_target(vb)) > @@ -971,6 +1030,8 @@ static void virtballoon_remove(struct virtio_device *vdev) > destroy_workqueue(vb->balloon_wq); > } > > + if (page_reporting_flag) > + page_reporting_disable(&vb->page_reporting_conf); I think you should not disable it if the feature bit was never offered in the first place, right? > remove_common(vb); > #ifdef CONFIG_BALLOON_COMPACTION > if (vb->vb_dev_info.inode) (...)