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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 0521AC3F2D7 for ; Tue, 3 Mar 2020 09:13:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A2C8C214D8 for ; Tue, 3 Mar 2020 09:13:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A2C8C214D8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1E74A6B0005; Tue, 3 Mar 2020 04:13:29 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 197E26B0006; Tue, 3 Mar 2020 04:13:29 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 062116B0007; Tue, 3 Mar 2020 04:13:29 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0158.hostedemail.com [216.40.44.158]) by kanga.kvack.org (Postfix) with ESMTP id E03EC6B0005 for ; Tue, 3 Mar 2020 04:13:28 -0500 (EST) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 98006180AD801 for ; Tue, 3 Mar 2020 09:13:28 +0000 (UTC) X-FDA: 76553487696.12.rail20_759c6163c8922 X-HE-Tag: rail20_759c6163c8922 X-Filterd-Recvd-Size: 3830 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf03.hostedemail.com (Postfix) with ESMTP for ; Tue, 3 Mar 2020 09:13:28 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4D0B62F; Tue, 3 Mar 2020 01:13:27 -0800 (PST) Received: from [10.162.16.51] (p8cg001049571a15.blr.arm.com [10.162.16.51]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 802903F6C4; Tue, 3 Mar 2020 01:13:23 -0800 (PST) From: Anshuman Khandual Subject: Re: [RFC 3/3] mm/vma: Introduce some more VMA flag wrappers To: Hugh Dickins Cc: linux-mm@kvack.org, "David S. Miller" , Alexey Dobriyan , Andrew Morton , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <1583131666-15531-1-git-send-email-anshuman.khandual@arm.com> <1583131666-15531-4-git-send-email-anshuman.khandual@arm.com> Message-ID: Date: Tue, 3 Mar 2020 14:43:21 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 03/03/2020 12:04 PM, Hugh Dickins wrote: > On Mon, 2 Mar 2020, Anshuman Khandual wrote: > >> This adds the following new VMA flag wrappers which will replace current >> open encodings across various places. This should not have any functional >> implications. >> >> vma_is_dontdump() >> vma_is_noreserve() >> vma_is_special() >> vma_is_locked() >> vma_is_mergeable() >> vma_is_softdirty() >> vma_is_thp() >> vma_is_nothp() > > Why?? Please don't. I am not at all keen on your 1/3 and 2/3 (some > of us actually like to see what the VM_ flags are where they're used, > without having to chase through scattered wrappers hiding them), > but this 3/3 particularly upset me. Can understand your reservations regarding 3/3. But I had called that out in the series cover letter that this patch can be dropped if related code churn is not justified. But 1/3 does create a default flag combination for VM_DATA_DEFAULT_FLAGS with a value that is used by multiple platforms at the moment. This is very similar to the existing VM_STACK_DEFAULT_FLAGS which has a default value. Then why cannot VM_DATA_DEFAULT_FLAGS have one ? More over this also saves some code duplication across platforms. Regarding the patch 2/3, when there are many existing VMA flag overrides like VM_STACK_FLAGS, VM_STACK_INCOMPLETE_SETUP, VM_INIT_DEF_MASK etc why cannot a commonly used VMA flag combination with a very specific meaning (i.e accessibility) get one. Do you have any particular concern here which I might be missing. > > There is a good reason for the (hideously named) is_vm_hugetlb_page(vma): > to save "#ifdef CONFIG_HUGETLB_PAGE"s all over (though I suspect the > same could have been achieved much more nicely by #define VM_HUGETLB 0); > but hiding all flags in vma_is_whatever()s is counter-productive churn. Makes sense, I can understand your reservation here. > > Improved readability? Not to my eyes. As mentioned before, I dont feel strongly about patch 3/3 and will drop.