From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751461AbcAAI0j (ORCPT ); Fri, 1 Jan 2016 03:26:39 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52089 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751239AbcAAI0g (ORCPT ); Fri, 1 Jan 2016 03:26:36 -0500 Date: Fri, 1 Jan 2016 10:26:32 +0200 From: "Michael S. Tsirkin" To: Minchan Kim Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Konstantin Khlebnikov , Rafael Aquini , stable@vger.kernel.org Subject: Re: [PATCH 1/2] virtio_balloon: fix race by fill and leak Message-ID: <20160101082632.GA10656@redhat.com> References: <1451259313-26353-1-git-send-email-minchan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1451259313-26353-1-git-send-email-minchan@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 28, 2015 at 08:35:12AM +0900, Minchan Kim wrote: > 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 Acked-by: Michael S. Tsirkin > --- > 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