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=-3.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 420BCC2BA2B for ; Thu, 9 Apr 2020 14:09:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 019DC20692 for ; Thu, 9 Apr 2020 14:09:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="RuVM92Ss" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 019DC20692 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=shutemov.name Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A30AD8E000D; Thu, 9 Apr 2020 10:09:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9DF9B8E0006; Thu, 9 Apr 2020 10:09:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 880DA8E000D; Thu, 9 Apr 2020 10:09:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0240.hostedemail.com [216.40.44.240]) by kanga.kvack.org (Postfix) with ESMTP id 76E778E0006 for ; Thu, 9 Apr 2020 10:09:18 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 4988DA8FB for ; Thu, 9 Apr 2020 14:09:18 +0000 (UTC) X-FDA: 76688498796.06.crush98_341478deb9b08 X-HE-Tag: crush98_341478deb9b08 X-Filterd-Recvd-Size: 4338 Received: from mail-lj1-f193.google.com (mail-lj1-f193.google.com [209.85.208.193]) by imf15.hostedemail.com (Postfix) with ESMTP for ; Thu, 9 Apr 2020 14:09:17 +0000 (UTC) Received: by mail-lj1-f193.google.com with SMTP id i20so11580542ljn.6 for ; Thu, 09 Apr 2020 07:09:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=uv8UP3Wi+CGR6aJHvj/vA4c90Y3msAt+vS5SBdybyk4=; b=RuVM92SsPNRhm7BsWsPTbRCsSBTx+CH3ocev16sXCwZDfS51MYTN9xOJSpDgsezMWC RBDfi5pOVjMcKiRauCnRnAIJ2rTa8RsVD8QCoqI5E+UTcTbOawe/iKLi92mZ+aFYUTi7 v+O4AIxbnCQenN38OXdP2gK8A9kGkYKBvaR0tIsNFTORsVuyzv482nrRLZ1cE56F8FUr ii47IUIro7DgOwl41fPTBw3zG4LmFF3x0KWOSt4hg/AF3DJ2X9Q7uG5N8IU5Y1hkz+yf kvYchwSq0UOTxBnliUAu4C86E2gE6TzG7rRlnBN4eNlg8P3m3TE9E+5x0fOgjaEQgEp6 HQRg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=uv8UP3Wi+CGR6aJHvj/vA4c90Y3msAt+vS5SBdybyk4=; b=J1u5m3+SDfULyXqFU6zzIZLh0aQ+ytSMYYTl+D1JvR+5kF9uugggDrdSnqVmyA3wmz zZBvu/LVFCVf5YjXrCREU7mRq6zvbulJDCQqBO4kJDONYFJp2SQ5bPj8m1oGOvYnc7Kd FUpwHrR6X1hzwVRnKEkoj7PRLlSLP5jjx4IBXSa2Ck5ZeQAu7hCCP0pKkpeX55awXosm HssmT8FpQxjVj+oz40daKyDTjWJ/vVyLsjPzmO5p8EsWujQeGNFMN42F0ya2iADGW8SU XnB6k6uVwr7pCVTResyt79wxnfl04blQ9nBvauTQOxJrXqiHHcMKD1ATjc4SGC1+N9BY 1tew== X-Gm-Message-State: AGi0PuY5G3Ku/uh2vb0CP4SBCVFwFA+3vVvrug++vzu4Rst+FQKdp3DF BReNGH1nS2mdMGzPCBXv4z0TZla7Y2Y= X-Google-Smtp-Source: APiQypJLpjc3e2tA3QUEZWu18kTW6vg2YCD06Mfyfz/Shzqjy0SVO5btkGFUIy3eE7Yhfbiby9B+Xw== X-Received: by 2002:a05:651c:14b:: with SMTP id c11mr306727ljd.27.1586441356253; Thu, 09 Apr 2020 07:09:16 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id u4sm15277511ljj.44.2020.04.09.07.09.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Apr 2020 07:09:15 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id B7370102132; Thu, 9 Apr 2020 17:09:14 +0300 (+03) Date: Thu, 9 Apr 2020 17:09:14 +0300 From: "Kirill A. Shutemov" To: Matthew Wilcox Cc: linux-mm@kvack.org, kirill.shutemov@linux.intel.com, pasha.tatashin@soleen.com Subject: Re: [PATCH 1/5] mm: Constify a lot of struct page arguments Message-ID: <20200409140914.u3mff4xrk5u4tvht@box> References: <20200408150148.25290-1-willy@infradead.org> <20200408150148.25290-2-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200408150148.25290-2-willy@infradead.org> 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, Apr 08, 2020 at 08:01:44AM -0700, Matthew Wilcox wrote: > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 4aba6c0c2ba8..a8c3fa076f43 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -221,15 +221,8 @@ struct page { > #endif > } _struct_page_alignment; > > -static inline atomic_t *compound_mapcount_ptr(struct page *page) > -{ > - return &page[1].compound_mapcount; > -} > - > -static inline atomic_t *compound_pincount_ptr(struct page *page) > -{ > - return &page[2].hpage_pinned_refcount; > -} > +#define compound_mapcount_ptr(page) (&(page)[1].compound_mapcount) > +#define compound_pincount_ptr(page) (&(page)[2].hpage_pinned_refcount) Looks like this conversion is not covered by the reason given in the commit message. Hm? > +#define compound_head(page) ({ \ > + __typeof__(page) _page = page; \ > + unsigned long head = READ_ONCE(_page->compound_head); \ > + if (unlikely(head & 1)) \ > + _page = (void *)(head - 1); \ > + _page; \ > +}) Ugh.. Other option would be to make compound_head() take 'const struct page *' and return 'void *'. It arguably would provide better type safety, no? -- Kirill A. Shutemov