From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f44.google.com (mail-qg0-f44.google.com [209.85.192.44]) by kanga.kvack.org (Postfix) with ESMTP id 9240A6B02BC for ; Sun, 27 Dec 2015 18:36:17 -0500 (EST) Received: by mail-qg0-f44.google.com with SMTP id 6so60239069qgy.1 for ; Sun, 27 Dec 2015 15:36:17 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id z139si62144521qka.98.2015.12.27.15.36.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 27 Dec 2015 15:36:17 -0800 (PST) Date: Sun, 27 Dec 2015 18:36:11 -0500 From: Rafael Aquini 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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, 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