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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,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 38DCEC433ED for ; Wed, 5 May 2021 18:59:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AD09261106 for ; Wed, 5 May 2021 18:59:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AD09261106 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 27ADD6B0074; Wed, 5 May 2021 14:59:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 229D76B0075; Wed, 5 May 2021 14:59:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0CAFA6B0078; Wed, 5 May 2021 14:59:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0100.hostedemail.com [216.40.44.100]) by kanga.kvack.org (Postfix) with ESMTP id E79376B0074 for ; Wed, 5 May 2021 14:59:53 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id A0B4B181AEF10 for ; Wed, 5 May 2021 18:59:53 +0000 (UTC) X-FDA: 78108091866.28.FAE493F Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf30.hostedemail.com (Postfix) with ESMTP id BE94EE00011F for ; Wed, 5 May 2021 18:59:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=7Ts3m9Dmu8TbFp1Zou/lAmdxBv7vUaszRSdZtygGL3s=; b=eKuCCZ+YLLh/IfsiA2w2TJnrVq OgsO6w/D0Fq0g3dHXII9KGzSc/qTA7NBXv38JF7QEOyGbRPI+lQzcqZ/aYb1SJdMtttFxdlIc3UQ/ gsmOyS+xv0AUj0u8nQICpJLKl56GUf2FrWTZOM83hUHEaRUlaciSIebpnb1qCyo4mDgKcSsFsux3z GpYO6JkYOwrZCA4dlgPSWLWUiu+cO4qfsDeNbKDkLDDBtW5y5BKAsBa/6OCccyEKi+VnNszzSVzSv zt9omkCl03D90I/M5UK6bjixbmbSfSvHuxKrCa402BYQq/BIo+9XdgPVWy1RoH0ejumnnoRoDgRUG r6n6Og3w==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1leMjW-000nXf-H1; Wed, 05 May 2021 18:59:01 +0000 Date: Wed, 5 May 2021 19:58:54 +0100 From: Matthew Wilcox To: Dan Williams Cc: Joao Martins , Linux MM , Ira Weiny , linux-nvdimm , Jason Gunthorpe , Jane Chu , Muchun Song , Mike Kravetz , Andrew Morton Subject: Re: [PATCH v1 04/11] mm/memremap: add ZONE_DEVICE support for compound pages Message-ID: <20210505185854.GI1847222@casper.infradead.org> References: <20210325230938.30752-1-joao.m.martins@oracle.com> <20210325230938.30752-5-joao.m.martins@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=eKuCCZ+Y; dmarc=none; spf=none (imf30.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Rspamd-Server: rspam03 X-Stat-Signature: gobjczp7hi949hsjef64w9udkm6cicua X-Rspamd-Queue-Id: BE94EE00011F Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf30; identity=mailfrom; envelope-from=""; helo=casper.infradead.org; client-ip=90.155.50.34 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1620241167-253443 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, May 05, 2021 at 11:44:29AM -0700, Dan Williams wrote: > > @@ -6285,6 +6285,8 @@ void __ref memmap_init_zone_device(struct zone *zone, > > unsigned long pfn, end_pfn = start_pfn + nr_pages; > > struct pglist_data *pgdat = zone->zone_pgdat; > > struct vmem_altmap *altmap = pgmap_altmap(pgmap); > > + unsigned int pfn_align = pgmap_pfn_align(pgmap); > > + unsigned int order_align = order_base_2(pfn_align); > > unsigned long zone_idx = zone_idx(zone); > > unsigned long start = jiffies; > > int nid = pgdat->node_id; > > @@ -6302,10 +6304,30 @@ void __ref memmap_init_zone_device(struct zone *zone, > > nr_pages = end_pfn - start_pfn; > > } > > > > - for (pfn = start_pfn; pfn < end_pfn; pfn++) { > > + for (pfn = start_pfn; pfn < end_pfn; pfn += pfn_align) { > > pfn_align is in bytes and pfn is in pages... is there a "pfn_align >>= > PAGE_SHIFT" I missed somewhere? If something is measured in bytes, I like to use size_t (if it's in memory) and loff_t (if it's on storage). The compiler doesn't do anything useful to warn you, but it's a nice indication to humans about what's going on. And it removes the temptation to do 'pfn_align >>= PAGE_SHIFT' and suddenly take pfn_align from being measured in bytes to being measured in pages.