From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755450Ab1KYNRO (ORCPT ); Fri, 25 Nov 2011 08:17:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53797 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754099Ab1KYNRN (ORCPT ); Fri, 25 Nov 2011 08:17:13 -0500 Date: Fri, 25 Nov 2011 14:12:41 +0100 From: Andrea Arcangeli To: Youquan Song Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, wli@holomorphy.com, david.woodhouse@intel.com, allen.m.kay@intel.com, mtosatti@redhat.com, chrisw@redhat.com, andi@firstfloor.org, chaohong.guo@intel.com, Youquan Song Subject: Re: [PATCH 1/2] thp: Add compound tail page _mapcount when mapped Message-ID: <20111125131241.GZ8397@redhat.com> References: <1322200030-26350-1-git-send-email-youquan.song@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1322200030-26350-1-git-send-email-youquan.song@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Both are needed to take care of CONFIG_DEBUG_VM false positives. Worst case a false positive hits, but if it doesn't there was no risk because the tail page refcounting isn't actively used by that code and the refcounting on the head page was done right already. Thanks, Andrea