Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754864AbbL0XgS (ORCPT ); Sun, 27 Dec 2015 18:36:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57994 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752690AbbL0XgQ (ORCPT ); Sun, 27 Dec 2015 18:36:16 -0500 Date: Sun, 27 Dec 2015 18:36:11 -0500 From: Rafael Aquini To: Minchan Kim Cc: Andrew Morton , "Michael S. Tsirkin" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Konstantin Khlebnikov , stable@vger.kernel.org Subject: Re: [PATCH 1/2] virtio_balloon: fix race by fill and leak Message-ID: <20151227233610.GB624@t510.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> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1502 Lines: 43 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 > --- > 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 > Acked-by: Rafael Aquini -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/