From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932549AbbC0QDI (ORCPT ); Fri, 27 Mar 2015 12:03:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59560 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932533AbbC0QDG (ORCPT ); Fri, 27 Mar 2015 12:03:06 -0400 From: Vitaly Kuznetsov To: "K. Y. Srinivasan" Cc: Haiyang Zhang , devel@linuxdriverproject.org, linux-kernel@vger.kernel.org, Dexuan Cui , Laszlo Ersek Subject: [PATCH 1/2] Drivers: hv: hv_balloon: correctly handle val.freeram In-Reply-To: <1427472180-21439-1-git-send-email-vkuznets@redhat.com> References: <1427472180-21439-1-git-send-email-vkuznets@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 'Drivers: hv: hv_balloon: refuse to balloon below the floor' fix does not correctly handle the case when val.freeram < num_pages as val.freeram is __kernel_ulong_t and the 'val.freeram - num_pages' value will be a huge positive value instead of being negative. Usually host doesn't ask us to balloon more than val.freeram but in case he have a memory hog started after we post the last pressure report we can get into troubles. Suggested-by: Laszlo Ersek Signed-off-by: Vitaly Kuznetsov --- drivers/hv/hv_balloon.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index d8c5802..20bfe36 100644 --- a/drivers/hv/hv_balloon.c +++ b/drivers/hv/hv_balloon.c @@ -1145,7 +1145,7 @@ static void balloon_up(struct work_struct *dummy) floor = compute_balloon_floor(); /* Refuse to balloon below the floor, keep the 2M granularity. */ - if (val.freeram - num_pages < floor) { + if (val.freeram < num_pages || val.freeram - num_pages < floor) { num_pages = val.freeram > floor ? (val.freeram - floor) : 0; num_pages -= num_pages % PAGES_IN_2M; } -- 1.9.3