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 4FF99C433F5 for ; Wed, 2 Mar 2022 21:22:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AB0E78D0002; Wed, 2 Mar 2022 16:22:00 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A5FBF8D0001; Wed, 2 Mar 2022 16:22:00 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 94E9C8D0002; Wed, 2 Mar 2022 16:22:00 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id 8555A8D0001 for ; Wed, 2 Mar 2022 16:22:00 -0500 (EST) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 4D77462524 for ; Wed, 2 Mar 2022 21:22:00 +0000 (UTC) X-FDA: 79200718800.09.87B323E Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf17.hostedemail.com (Postfix) with ESMTP id 9AA2440004 for ; Wed, 2 Mar 2022 21:21:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Sender:In-Reply-To:Content-Type: MIME-Version:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:References; bh=QGQwHCQX3j+TcKKZtmw4Nue4CTnQRxDyxtp3O3ZauA8=; b=lYcaijEmRslYq3x6eyRWtLcAQq wgJKfe0IUb0dX0eXRFwcI6S944b3Z5XXManZwwaU0TDGnbXOGosC5c7Nu4I9eC5zC8TbwlHSvFGEg wSAI45wlWP0NsAInVV5SjB4H/HtpONAc0AUA7hTtXdbayCwIbPdvWj/m3HrPsLfTv/GH10RACIqi4 7csgyH7+04vAD1fd4l9ef23dhGfG7l2qPzm/+yURq3r8Ly8FOw8gX63GWTBnQCoT8PMvEuBzd7zIf +v5tpjWY4p7SDs+rgxj/+LqQ1HVMqSRcKh1t7TgAdTLSBkni4sGEcpSBwsF4dnCUkyTKfOaYcMVAc Sk/hxRBA==; Received: from mcgrof by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nPWPt-004Gph-Mq; Wed, 02 Mar 2022 21:21:49 +0000 Date: Wed, 2 Mar 2022 13:21:49 -0800 From: Luis Chamberlain To: Muchun Song Cc: corbet@lwn.net, mike.kravetz@oracle.com, akpm@linux-foundation.org, keescook@chromium.org, yzaikin@google.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, duanxiongchun@bytedance.com, smuchun@gmail.com, Adam Manzanares , Davidlohr Bueso Subject: Re: [PATCH v2 1/3] mm: hugetlb: disable freeing vmemmap pages when struct page crosses page boundaries Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220302083758.32528-2-songmuchun@bytedance.com> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 9AA2440004 X-Stat-Signature: e7nkntcra8wk3njygezh9sjs96166p5m Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=lYcaijEm; spf=none (imf17.hostedemail.com: domain of mcgrof@infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=mcgrof@infradead.org; dmarc=fail reason="No valid SPF, DKIM not aligned (relaxed)" header.from=kernel.org (policy=none) X-Rspam-User: X-HE-Tag: 1646256119-947357 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000003, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Mar 02, 2022 at 04:37:56PM +0800, Muchun Song wrote: > If CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON is enabled and the size > of "struct page" is not power of two, we cannot optimize vmemmap pages > of HugeTLB pages. We should disable this feature in this case. The commit log does not descrie what happens if this is left enabled in that case? Is this a fix? Why would it be a fix? Was something failing? How did you spot this issue? What are the consequences of not applying this patch? Luis