From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D75A4ECDFB3 for ; Tue, 17 Jul 2018 18:32:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9EE7A2077B for ; Tue, 17 Jul 2018 18:32:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9EE7A2077B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730503AbeGQTGo (ORCPT ); Tue, 17 Jul 2018 15:06:44 -0400 Received: from mga11.intel.com ([192.55.52.93]:42790 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729976AbeGQTGo (ORCPT ); Tue, 17 Jul 2018 15:06:44 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Jul 2018 11:32:51 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,366,1526367600"; d="scan'208";a="75552242" Received: from ray.jf.intel.com (HELO [10.7.201.150]) ([10.7.201.150]) by orsmga002.jf.intel.com with ESMTP; 17 Jul 2018 11:32:50 -0700 Subject: Re: [PATCH v2 2/7] mm/swapfile.c: Replace some #ifdef with IS_ENABLED() To: "Huang, Ying" , Andrew Morton References: <20180717005556.29758-1-ying.huang@intel.com> <20180717005556.29758-3-ying.huang@intel.com> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Hocko , Johannes Weiner , Shaohua Li , Hugh Dickins , Minchan Kim , Rik van Riel , Daniel Jordan , Dan Williams From: Dave Hansen Openpgp: preference=signencrypt Autocrypt: addr=dave.hansen@linux.intel.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180717005556.29758-3-ying.huang@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > @@ -878,6 +877,11 @@ static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) > unsigned long offset, i; > unsigned char *map; > > + if (!IS_ENABLED(CONFIG_THP_SWAP)) { > + VM_WARN_ON_ONCE(1); > + return 0; > + } I see you seized the opportunity to keep this code gloriously unencumbered by pesky comments. This seems like a time when you might have slipped up and been temped to add a comment or two. Guess not. :) Seriously, though, does it hurt us to add a comment or two to say something like: /* * Should not even be attempting cluster allocations when * huge page swap is disabled. Warn and fail the allocation. */ if (!IS_ENABLED(CONFIG_THP_SWAP)) { VM_WARN_ON_ONCE(1); return 0; }