From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f70.google.com (mail-oi0-f70.google.com [209.85.218.70]) by kanga.kvack.org (Postfix) with ESMTP id 55E256B025E for ; Thu, 18 Jan 2018 17:37:29 -0500 (EST) Received: by mail-oi0-f70.google.com with SMTP id e9so13667034oib.10 for ; Thu, 18 Jan 2018 14:37:29 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id 20si3256750oii.146.2018.01.18.14.37.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Jan 2018 14:37:28 -0800 (PST) Date: Fri, 19 Jan 2018 00:37:18 +0200 From: "Michael S. Tsirkin" Subject: Re: [PATCH v22 3/3] virtio-balloon: don't report free pages when page poisoning is enabled Message-ID: <20180119003650-mutt-send-email-mst@kernel.org> References: <1516165812-3995-1-git-send-email-wei.w.wang@intel.com> <1516165812-3995-4-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: <1516165812-3995-4-git-send-email-wei.w.wang@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Wei Wang Cc: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, akpm@linux-foundation.org, pbonzini@redhat.com, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com On Wed, Jan 17, 2018 at 01:10:12PM +0800, Wei Wang wrote: > The guest free pages should not be discarded by the live migration thread > when page poisoning is enabled with PAGE_POISONING_NO_SANITY=n, because > skipping the transfer of such poisoned free pages will trigger false > positive when new pages are allocated and checked on the destination. > This patch adds a config field, poison_val. Guest writes to the config > field to tell the host about the poisoning value. The value will be 0 in > the following cases: > 1) PAGE_POISONING_NO_SANITY is enabled; > 2) page poisoning is disabled; or > 3) PAGE_POISONING_ZERO is enabled. > > Signed-off-by: Wei Wang > Suggested-by: Michael S. Tsirkin > Cc: Michal Hocko Pls squash with the previous patch. It's not nice to break a config, then fix it up later. > --- > drivers/virtio/virtio_balloon.c | 8 ++++++++ > include/uapi/linux/virtio_balloon.h | 2 ++ > 2 files changed, 10 insertions(+) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index b9561a5..5a42235 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -706,6 +706,7 @@ static struct file_system_type balloon_fs = { > static int virtballoon_probe(struct virtio_device *vdev) > { > struct virtio_balloon *vb; > + __u32 poison_val; > int err; > > if (!vdev->config->get) { > @@ -740,6 +741,13 @@ static int virtballoon_probe(struct virtio_device *vdev) > WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0); > INIT_WORK(&vb->report_free_page_work, report_free_page_func); > vb->stop_cmd_id = VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID; > + if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY) || > + !page_poisoning_enabled()) > + poison_val = 0; > + else > + poison_val = PAGE_POISON; > + virtio_cwrite(vb->vdev, struct virtio_balloon_config, > + poison_val, &poison_val); > } > > vb->nb.notifier_call = virtballoon_oom_notify; > diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h > index 55e2456..5861876 100644 > --- a/include/uapi/linux/virtio_balloon.h > +++ b/include/uapi/linux/virtio_balloon.h > @@ -47,6 +47,8 @@ struct virtio_balloon_config { > __u32 actual; > /* Free page report command id, readonly by guest */ > __u32 free_page_report_cmd_id; > + /* Stores PAGE_POISON if page poisoning with sanity check is in use */ > + __u32 poison_val; > }; > > #define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */ > -- > 2.7.4 -- 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