From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f169.google.com (mail-pf0-f169.google.com [209.85.192.169]) by kanga.kvack.org (Postfix) with ESMTP id A71336B02BD for ; Sun, 27 Dec 2015 18:34:12 -0500 (EST) Received: by mail-pf0-f169.google.com with SMTP id e65so51689845pfe.1 for ; Sun, 27 Dec 2015 15:34:12 -0800 (PST) Received: from lgeamrelo13.lge.com (LGEAMRELO13.lge.com. [156.147.23.53]) by mx.google.com with ESMTPS id 86si38188548pfs.88.2015.12.27.15.34.10 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sun, 27 Dec 2015 15:34:11 -0800 (PST) From: Minchan Kim Subject: [PATCH 1/2] virtio_balloon: fix race by fill and leak Date: Mon, 28 Dec 2015 08:35:12 +0900 Message-Id: <1451259313-26353-1-git-send-email-minchan@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: "Michael S. Tsirkin" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Konstantin Khlebnikov , Rafael Aquini , Minchan Kim , stable@vger.kernel.org During my compaction-related stuff, I encountered a bug with ballooning. With repeated inflating and deflating cycle, guest memory( ie, cat /proc/meminfo | grep MemTotal) is decreased and couldn't be recovered. The reason is balloon_lock doesn't cover release_pages_balloon so struct virtio_balloon fields could be overwritten by race of fill_balloon(e,g, vb->*pfns could be critical). This patch fixes it in my test. Cc: Signed-off-by: Minchan Kim --- drivers/virtio/virtio_balloon.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 7efc32945810..7d3e5d0e9aa4 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -209,8 +209,8 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) */ if (vb->num_pfns != 0) tell_host(vb, vb->deflate_vq); - mutex_unlock(&vb->balloon_lock); release_pages_balloon(vb); + mutex_unlock(&vb->balloon_lock); return num_freed_pages; } -- 1.9.1 -- 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