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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id c1-20020a05622a024100b0039cc0fbdb61sm10856656qtx.53.2022.11.09.18.10.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Nov 2022 18:10:14 -0800 (PST) Date: Wed, 9 Nov 2022 18:10:12 -0800 (PST) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Sidhartha Kumar cc: Hugh Dickins , Andrew Morton , "Kirill A. Shutemov" , Matthew Wilcox , David Hildenbrand , Vlastimil Babka , Peter Xu , Yang Shi , John Hubbard , Mike Kravetz , Muchun Song , Miaohe Lin , Naoya Horiguchi , Mina Almasry , James Houghton , Zach O'Keefe , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/3] mm,hugetlb: use folio fields in second tail page In-Reply-To: Message-ID: <7f60bcac-a2e5-9c4b-8a8f-e972a93e116@google.com> References: <5f52de70-975-e94f-f141-543765736181@google.com> <3818cc9a-9999-d064-d778-9c94c5911e6@google.com> <5bd8a365-e2c5-a721-1257-81ec4ae0c626@oracle.com> <3934b34-ae2f-2119-9a68-33e51e909795@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=ckQT3Ln0; spf=pass (imf01.hostedemail.com: domain of hughd@google.com designates 209.85.222.182 as permitted sender) smtp.mailfrom=hughd@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1668046216; a=rsa-sha256; cv=none; b=4sBMjLsZicEVQhDsOnP8dw3+bxVyWNo0V3Ph+mu9uUSpDoGK8jgbSqxE1w40dRFQ25mk2/ b9RMQdB+HN38djMAJuVMdenk/wlRGf1dcODtOGuO4/tE4YjWRnL7oGROCAsl7y8p2iH2N3 cklhwtWm6toDVUg+OYAzup8oB8Pc8vk= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1668046216; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=zPoVaZI3+eUsBLgHzkw8YZRMFuPpzhPKpLA9H61td34=; b=wTjipvxaXE3v7m1iglYF5qPfA7fkP3U6kdYTrqHaVyNbSq7nUpnq5MYjaB9M2D8tt5RaDK h7Jl/QrSK59quBNhXB+1GZSQPt0YNm3PdfTq16FcldyXf+0TcOnBXuMBjJknOTulm+wzod /zWepSyM7nr352Q62heP988r/MtNc8w= X-Stat-Signature: n146m4z3fq6iucab55ruujyqo3s67agj X-Rspamd-Queue-Id: 62C5540009 Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=ckQT3Ln0; spf=pass (imf01.hostedemail.com: domain of hughd@google.com designates 209.85.222.182 as permitted sender) smtp.mailfrom=hughd@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1668046216-394643 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 Wed, 9 Nov 2022, Sidhartha Kumar wrote: > On 11/3/22 9:29 PM, Hugh Dickins wrote: > > > >> Should the usage of page_1 and page_2 also be documented here? > > You must have something interesting in mind to document about them, > > but I cannot guess what! They are for field alignment, not for use. > > (page_2 to help when/if someone needs to add another pageful.) > > > > Do you mean that I should copy the > > /* private: the union with struct page is transitional */ > > comment from above the original "struct page page;" line I copied? > > Or give all three of them a few underscores to imply not for use? > > I think the underscores with a comment about not for use could be helpful. I've given them two underscores (but not to the original "struct page page", since a build showed that used as "page" elsewhere, not just for alignment). I'm sorry, but I've not given them any comment: I don't think they belong in the commented fields section (_flags_1 etc), "page" is not there; and I'm, let's be honest, terrified of dabbling in this kerneldoc area - feel very fortunate to have escaped attack by a robot for my additions so far. I'll leave adding comment to you or other cognoscenti. Hugh