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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 7817DC433EF for ; Tue, 12 Jun 2018 03:15:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 35488208B9 for ; Tue, 12 Jun 2018 03:15:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 35488208B9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=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 S1754082AbeFLDPf (ORCPT ); Mon, 11 Jun 2018 23:15:35 -0400 Received: from mga14.intel.com ([192.55.52.115]:31608 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751050AbeFLDPc (ORCPT ); Mon, 11 Jun 2018 23:15:32 -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 fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jun 2018 20:15:33 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,213,1526367600"; d="scan'208";a="66239368" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.13.118]) by orsmga002.jf.intel.com with ESMTP; 11 Jun 2018 20:15:29 -0700 From: "Huang\, Ying" To: Daniel Jordan Cc: Andrew Morton , , , "Kirill A. Shutemov" , Andrea Arcangeli , Michal Hocko , Johannes Weiner , Shaohua Li , Hugh Dickins , Minchan Kim , Rik van Riel , Dave Hansen , Naoya Horiguchi , Zi Yan Subject: Re: [PATCH -mm -V3 03/21] mm, THP, swap: Support PMD swap mapping in swap_duplicate() References: <20180523082625.6897-1-ying.huang@intel.com> <20180523082625.6897-4-ying.huang@intel.com> <20180611204231.ojhlyrbmda6pouxb@ca-dmjordan1.us.oracle.com> <87o9ggpzlk.fsf@yhuang-dev.intel.com> Date: Tue, 12 Jun 2018 11:15:28 +0800 In-Reply-To: <87o9ggpzlk.fsf@yhuang-dev.intel.com> (Ying Huang's message of "Tue, 12 Jun 2018 09:23:19 +0800") Message-ID: <87k1r4puen.fsf@yhuang-dev.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "Huang, Ying" writes: >> On Wed, May 23, 2018 at 04:26:07PM +0800, Huang, Ying wrote: >>> @@ -3516,11 +3512,39 @@ static int __swap_duplicate(swp_entry_t entry, unsigned char usage) >> >> Two comments about this part of __swap_duplicate as long as you're moving it to >> another function: >> >> } else if (count || has_cache) { >> >> if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX) /* #1 */ >> count += usage; >> else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) /* #2 */ >> err = -EINVAL; >> >> #1: __swap_duplicate_locked might use >> >> VM_BUG_ON(usage != SWAP_HAS_CACHE && usage != 1); >> >> to document the unstated assumption that usage is 1 (otherwise count could >> overflow). > > Sounds good. Will do this. Found usage parameter of __swap_duplicate() could be SWAP_MAP_SHMEM too. We can improve the parameter checking. But that appears not belong to this series. Best Regards, Huang, Ying