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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C811ECAAD5 for ; Fri, 2 Sep 2022 09:02:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EF6948D0018; Fri, 2 Sep 2022 05:02:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EA6718D0014; Fri, 2 Sep 2022 05:02:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D6E2C8D0018; Fri, 2 Sep 2022 05:02:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id C5CC08D0014 for ; Fri, 2 Sep 2022 05:02:13 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 9192F1211E4 for ; Fri, 2 Sep 2022 09:02:13 +0000 (UTC) X-FDA: 79866553746.08.889BF14 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf11.hostedemail.com (Postfix) with ESMTP id 55B2740050 for ; Fri, 2 Sep 2022 09:02:12 +0000 (UTC) Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4MJsL36Wz1znTyn; Fri, 2 Sep 2022 16:59:39 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggpemm500024.china.huawei.com (7.185.36.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 2 Sep 2022 17:02:08 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 2 Sep 2022 17:02:08 +0800 Content-Type: multipart/alternative; boundary="------------GGyBCt6VpG0zUD0echR5pj0L" Message-ID: <79d05f57-8b3a-2450-43bf-f45de53a8c8e@huawei.com> Date: Fri, 2 Sep 2022 17:02:07 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH 2/2] mm: add pageblock_aligned() macro Content-Language: en-US To: David Hildenbrand , Andrew Morton , CC: Mike Rapoport , Oscar Salvador , , Vlastimil Babka References: <20220902064751.17890-1-wangkefeng.wang@huawei.com> <20220902064751.17890-2-wangkefeng.wang@huawei.com> From: Kefeng Wang In-Reply-To: X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662109333; a=rsa-sha256; cv=none; b=Keo/u6heJmGE0emx9kBVe5nMph4FLNftAAqt4QmfHLQ3FJq6gmXEnhNWkmC038McOLAY5y /oA+9ajNBPgjzZ6a5O4uHUS7KperEIM+f8nJr8FfyVQyO6yXtWmG/8uQktRUO1937GhlTb k7Y5+vw2q7eY1qxFgSOUjLiDVKcWv6o= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=none; spf=pass (imf11.hostedemail.com: domain of wangkefeng.wang@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=wangkefeng.wang@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662109333; 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; bh=J2piAVLyNTxNG7dWxGfSEkKSz07kGyHkZyWCxz3Al4Y=; b=CphtQvf4dSq1qdWAPGpellU3hA8aFtlu13z5jw9pUtpnKXYyA/O9tB3GjQN9Z91zC+anYg 49nnxIHWdvBV66btGEe4AYEunvmY+EkLaoFOgh8RWfPjOs0G7pNessBnuBAGEmV8rgL4z2 5wdY4EBL2FAD09KWFJarnHoKKBuLLKg= X-Stat-Signature: ip44orj8p9yn9nt7ucwwoggimy3h9d1f X-Rspam-User: X-Rspamd-Queue-Id: 55B2740050 X-Rspamd-Server: rspam07 Authentication-Results: imf11.hostedemail.com; dkim=none; spf=pass (imf11.hostedemail.com: domain of wangkefeng.wang@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=wangkefeng.wang@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-HE-Tag: 1662109332-565660 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: --------------GGyBCt6VpG0zUD0echR5pj0L Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit On 2022/9/2 16:42, David Hildenbrand wrote: > On 02.09.22 08:47, Kefeng Wang wrote: >> Add pageblock_aligned() and use it to simplify code. >> >> Signed-off-by: Kefeng Wang >> --- > [...] > >> - unsigned long nr_pgmask = pageblock_nr_pages - 1; >> int nid = zone_to_nid(zone); >> unsigned long nr_pages = 0; >> int zid = zone_idx(zone); >> @@ -1977,7 +1974,7 @@ static unsigned long __init deferred_init_pages(struct zone *zone, >> if (!deferred_pfn_valid(pfn)) { >> page = NULL; >> continue; >> - } else if (!page || !(pfn & nr_pgmask)) { > > I didn't sleep too well this night and am tired, please tell me why I'm > wrong :) Wish you have a good reset :) > > "pfn & (pageblock_nr_pages - 1)" is true if the pageblock is not aligned > > E.g., pfn = 1, pageblock_nr_pages = 512 > > pfn & (pageblock_nr_pages - 1) > -> 1 & (512 - 1) > -> 1 & 511 > -> true > > "!(pfn & (pageblock_nr_pages - 1))" is true if the pageblock is aligned > -> !(true) > -> false > > > However, "!pageblock_aligned(1)" = true > > >> + } else if (!page || !pageblock_aligned(pfn)) { pageblock_aligned(pfn) IS_ALIGNED((unsigned long)(pfn), pageblock_nr_pages) #define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0) (((pfn) & (pageblock_nr_pages - 1)) == 0) -> ((1 & 512 -1) == 0) -> ((1 & 511) == 0) -> ((511) == 0) -> false right ? > > So shouldn't this be "pageblock_aligned(pfn)" > > > ? > >> page = pfn_to_page(pfn); >> } else { >> page++; > --------------GGyBCt6VpG0zUD0echR5pj0L Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: 7bit


On 2022/9/2 16:42, David Hildenbrand wrote:
On 02.09.22 08:47, Kefeng Wang wrote:

Add pageblock_aligned() and use it to simplify code.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---

[...]


-	unsigned long nr_pgmask = pageblock_nr_pages - 1;
 	int nid = zone_to_nid(zone);
 	unsigned long nr_pages = 0;
 	int zid = zone_idx(zone);
@@ -1977,7 +1974,7 @@ static unsigned long  __init deferred_init_pages(struct zone *zone,
 		if (!deferred_pfn_valid(pfn)) {
 			page = NULL;
 			continue;
-		} else if (!page || !(pfn & nr_pgmask)) {


I didn't sleep too well this night and am tired, please tell me why I'm
wrong :)
Wish you have a good reset :)

"pfn & (pageblock_nr_pages - 1)" is true if the pageblock is not aligned

E.g., pfn = 1, pageblock_nr_pages = 512

pfn & (pageblock_nr_pages - 1)
-> 1 & (512 - 1)
-> 1 & 511
-> true

"!(pfn & (pageblock_nr_pages - 1))" is true if the pageblock is aligned
-> !(true)
-> false


However, "!pageblock_aligned(1)" = true



+		} else if (!page || !pageblock_aligned(pfn)) {

pageblock_aligned(pfn) IS_ALIGNED((unsigned long)(pfn), pageblock_nr_pages)

#define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0)

(((pfn) & (pageblock_nr_pages - 1)) == 0)
-> ((1 & 512 -1) == 0)
-> ((1 & 511) == 0)
-> ((511) == 0)
-> false

right ? 


So shouldn't this be "pageblock_aligned(pfn)"


?


 			page = pfn_to_page(pfn);
 		} else {
 			page++;
--------------GGyBCt6VpG0zUD0echR5pj0L--