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 58802C433EF for ; Tue, 29 Mar 2022 13:08:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8F49A8D0002; Tue, 29 Mar 2022 09:08:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8A3E28D0001; Tue, 29 Mar 2022 09:08:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 745AB8D0002; Tue, 29 Mar 2022 09:08:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0084.hostedemail.com [216.40.44.84]) by kanga.kvack.org (Postfix) with ESMTP id 6682D8D0001 for ; Tue, 29 Mar 2022 09:08:31 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 201368249980 for ; Tue, 29 Mar 2022 13:08:31 +0000 (UTC) X-FDA: 79297452822.17.4F85525 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf15.hostedemail.com (Postfix) with ESMTP id 0EA3CA0019 for ; Tue, 29 Mar 2022 13:08:29 +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=wpco1Q/eEi8aY7+QQt48HMppPX+YBcw1colLd/STuVk=; b=Xjh5zsk14IxefscN8QozLeefcE hInBviNQnC99d/BzMZ2+cu+ZqSOFnM0lCj4+z8dJW0PnOuRawxL3sF3k/rfKiFb9tAWKgfCQQ/RKX G7wuZfgOxUiU/ynQJdRyvdoRbCWp3sitcXyPm4vAIDz79F9iw+cCHNuUz8QL7wwrc1WCoTfp8CL7B 4M+HvY1/7v0p4rKtrh4xm8sKsr16AvGSgaiku4cAzXH1zKz1NTFRUairi2wpfVTJsGdKGRpWGWY00 67JUpZ/VqDnhAx9W3GDOXfUq1FatC1j6FL/uR3O3UD2fBU10QbftfdXLlTpqRbHmW9QzIBno85iqY FGM8Lutg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nZBaC-000Ilg-K8; Tue, 29 Mar 2022 13:08:24 +0000 Date: Tue, 29 Mar 2022 14:08:24 +0100 From: Matthew Wilcox To: Chen Wandun Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org Subject: Re: [PATCH 2/2] mm: fix contiguous memmap assumptions about alloc/free pages Message-ID: References: <20220329130928.266323-1-chenwandun@huawei.com> <20220329130928.266323-3-chenwandun@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220329130928.266323-3-chenwandun@huawei.com> X-Rspam-User: X-Stat-Signature: 6dqz74k6jx5sxdfjs7w6e4s1fc8rg54f Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=Xjh5zsk1; spf=none (imf15.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 0EA3CA0019 X-HE-Tag: 1648559309-12088 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 Tue, Mar 29, 2022 at 09:09:28PM +0800, Chen Wandun wrote: > +#define page_nth(head, tail) (page_to_pfn(tail) - page_to_pfn(head)) Could we avoid reintroducing page_nth()? It is a terrible name. > @@ -1213,7 +1213,7 @@ static int free_tail_pages_check(struct page *head_page, struct page *page) > ret = 0; > goto out; > } > - switch (page - head_page) { > + switch (page_nth(head_page, page)) { > case 1: > /* the first tail page: ->mapping may be compound_mapcount() */ > if (unlikely(compound_mapcount(page))) { This is the only place you use it. I'd suggest free_tail_pages_check() should take 'i' as its second parameter instead of 'page + i', then there's no need to convert back to i.