From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) by kanga.kvack.org (Postfix) with ESMTP id 10BF66B71C7 for ; Wed, 5 Sep 2018 02:48:04 -0400 (EDT) Received: by mail-ed1-f71.google.com with SMTP id c16-v6so2173956edc.21 for ; Tue, 04 Sep 2018 23:48:04 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id z53-v6si1167658edc.320.2018.09.04.23.48.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 04 Sep 2018 23:48:02 -0700 (PDT) Date: Wed, 5 Sep 2018 08:48:00 +0200 From: Michal Hocko Subject: VM_BUG_ON_PGFLAGS with CONFIG_DEBUG_VM_PGFLAGS=n Message-ID: <20180905064800.GX14951@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: linux-mm@kvack.org Hi Kirill, while looking at something unrelated I have stumbled over %subj and I simply do not understand how BUILD_BUG_ON_INVALID is supposed to work for page flags checks which are dynamic by definition. BUILD_BUG_ON_INVALID is noop without any side effects unless __CHECKER__ is enabled when it evaluates to ((void )(sizeof((__force long )(e)))). How is this supposed to work? Am I just confused or BUILD_BUG_ON_INVALID is simply not a good fit here and all you wanted is the no side-effect nature of it? Thanks! -- Michal Hocko SUSE Labs