From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-7514-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 0F5DC985359 for ; Mon, 29 Jun 2020 08:06:29 +0000 (UTC) From: David Hildenbrand Date: Mon, 29 Jun 2020 10:06:15 +0200 Message-Id: <20200629080615.26022-1-david@redhat.com> MIME-Version: 1.0 Subject: [virtio-dev] [PATCH v2] virtio-balloon: always indicate S_DONE when migration fails Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable To: qemu-devel@nongnu.org Cc: "Michael S . Tsirkin" , virtio-dev@lists.oasis-open.org, David Hildenbrand , Alexander Duyck , Wei Wang , Alexander Duyck List-ID: If something goes wrong during precopy, before stopping the VM, we will never send a S_DONE indication to the VM, resulting in the hinted pages not getting released to be used by the guest OS (e.g., Linux). Easy to reproduce: 1. Start migration (e.g., HMP "migrate -d 'exec:gzip -c > STATEFILE.gz'") 2. Cancel migration (e.g., HMP "migrate_cancel") 3. Oberve in the guest (e.g., cat /proc/meminfo) that there is basically no free memory left. While at it, add similar locking to virtio_balloon_free_page_done() as done in virtio_balloon_free_page_stop. Locking is still weird, but that has to be sorted out separately. There is nothing to do in the PRECOPY_NOTIFY_COMPLETE case. Add some comments regarding S_DONE handling. Fixes: c13c4153f76d ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT") Reviewed-by: Alexander Duyck Cc: Wei Wang Cc: Alexander Duyck Signed-off-by: David Hildenbrand --- hw/virtio/virtio-balloon.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index 10507b2a43..8a84718490 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -628,8 +628,13 @@ static void virtio_balloon_free_page_done(VirtIOBalloo= n *s) { VirtIODevice *vdev =3D VIRTIO_DEVICE(s); =20 - s->free_page_report_status =3D FREE_PAGE_REPORT_S_DONE; - virtio_notify_config(vdev); + if (s->free_page_report_status !=3D FREE_PAGE_REPORT_S_DONE) { + /* See virtio_balloon_free_page_stop() */ + qemu_mutex_lock(&s->free_page_lock); + s->free_page_report_status =3D FREE_PAGE_REPORT_S_DONE; + qemu_mutex_unlock(&s->free_page_lock); + virtio_notify_config(vdev); + } } =20 static int @@ -653,17 +658,26 @@ virtio_balloon_free_page_report_notify(NotifierWithRe= turn *n, void *data) case PRECOPY_NOTIFY_SETUP: precopy_enable_free_page_optimization(); break; - case PRECOPY_NOTIFY_COMPLETE: - case PRECOPY_NOTIFY_CLEANUP: case PRECOPY_NOTIFY_BEFORE_BITMAP_SYNC: virtio_balloon_free_page_stop(dev); break; case PRECOPY_NOTIFY_AFTER_BITMAP_SYNC: if (vdev->vm_running) { virtio_balloon_free_page_start(dev); - } else { - virtio_balloon_free_page_done(dev); + break; } + /* + * Set S_DONE before migrating the vmstate, so the guest will reus= e + * all hinted pages once running on the destination. Fall through. + */ + case PRECOPY_NOTIFY_CLEANUP: + /* + * Especially, if something goes wrong during precopy or if migrat= ion + * is canceled, we have to properly communicate S_DONE to the VM. + */ + virtio_balloon_free_page_done(dev); + break; + case PRECOPY_NOTIFY_COMPLETE: break; default: virtio_error(vdev, "%s: %d reason unknown", __func__, pnd->reason)= ; --=20 2.26.2 --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org