From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933791AbcGKNKX (ORCPT ); Mon, 11 Jul 2016 09:10:23 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:35249 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932115AbcGKNKW (ORCPT ); Mon, 11 Jul 2016 09:10:22 -0400 X-Greylist: delayed 2461 seconds by postgrey-1.27 at vger.kernel.org; Mon, 11 Jul 2016 09:10:21 EDT From: "Denis V. Lunev" To: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Cc: den@openvz.org, Konstantin Neumoin , "Michael S. Tsirkin" Subject: [PATCH 1/1] balloon: check the number of available pages in leak balloon Date: Mon, 11 Jul 2016 15:28:59 +0300 Message-Id: <1468240139-16873-1-git-send-email-den@openvz.org> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Konstantin Neumoin The balloon has a special mechanism that is subscribed to the oom notification which leads to deflation for a fixed number of pages. The number is always fixed even when the balloon is fully deflated. But leak_balloon did not expect that the pages to deflate will be more than taken, and raise a "BUG" in balloon_page_dequeue when page list will be empty. So, the simplest solution would be to check that the number of releases pages is less or equal to the number taken pages. Signed-off-by: Konstantin Neumoin Signed-off-by: Denis V. Lunev CC: Michael S. Tsirkin --- drivers/virtio/virtio_balloon.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 476c0e3..f6ea8f4 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -202,6 +202,8 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) num = min(num, ARRAY_SIZE(vb->pfns)); mutex_lock(&vb->balloon_lock); + /* We can't release more pages than taken */ + num = min(num, (size_t)vb->num_pages); for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { page = balloon_page_dequeue(vb_dev_info); -- 2.1.4