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 DD708C433EF for ; Mon, 4 Apr 2022 16:06:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E74AF6B0071; Mon, 4 Apr 2022 12:06:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E23C16B0073; Mon, 4 Apr 2022 12:06:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CEC4B6B0074; Mon, 4 Apr 2022 12:06:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0019.hostedemail.com [216.40.44.19]) by kanga.kvack.org (Postfix) with ESMTP id C05666B0071 for ; Mon, 4 Apr 2022 12:06:42 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 799C6183E4B71 for ; Mon, 4 Apr 2022 16:06:32 +0000 (UTC) X-FDA: 79319674182.20.1D464D6 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf21.hostedemail.com (Postfix) with ESMTP id BB6FB1C0022 for ; Mon, 4 Apr 2022 16:06:30 +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=DEQK48DTwuMTMNUTpLWwhw+3ZXcCifB/CeMmKRj1wOY=; b=DAFAD08Dvu2jDB3R/moESGFvEY Qm/1sjjfXx8+Dbu/JriCkI2v/nHfqxIR3/zQ14SmSywHcDSXwXuiktZlD/CIbcT1jyYBGUljAV77+ 1pzvYO/rOvLU9dQDRxCnzq1P++ZpREsTjxFXOHzz+quDx4Mc6MIBYZ9dTflIdAstJXUEhkTf84IP0 pJ6RhSlHpWUcsMzoqBMnr+bRMJhxECh9GBRoKgxe/9JtY7xjjaVHq40lvRP4zCpUJHRehexqvCtbx 3peHdoR4IikvuNN7WwxM+FUwcHx3YizY9zb166RCLkGfzLZvjtHoJKWLaQ+g0dG+vW1CX9h8xFine 5qQ7q7Lg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nbPDh-005sCJ-7u; Mon, 04 Apr 2022 16:06:21 +0000 Date: Mon, 4 Apr 2022 17:06:21 +0100 From: Matthew Wilcox To: Zi Yan Cc: Naoya Horiguchi , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Michal Hocko , Naoya Horiguchi Subject: Re: v5.18-rc1: migratepages triggers VM_BUG_ON_FOLIO(folio_nr_pages(old) != nr_pages) Message-ID: References: <20220404132908.GA785673@u2004> <20220404151805.GA800317@u2004> <857E3E12-5C2D-4990-A667-79E1FC000291@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <857E3E12-5C2D-4990-A667-79E1FC000291@nvidia.com> X-Stat-Signature: 5whyk3qphwr5wopc4mcah53if7w1wzo5 Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=DAFAD08D; dmarc=none; spf=none (imf21.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: BB6FB1C0022 X-HE-Tag: 1649088390-13626 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 Mon, Apr 04, 2022 at 11:44:39AM -0400, Zi Yan wrote: > I am wondering if my change is the right fix or not. folios with order>0 > are still available when CONFIG_TRANSPARENT_HUGEPAGE is not set, right? That's the eventual plan, but it's not possible today. We need to be able to split large folios (eg in truncation) and that functionality is still under CONFIG_TRANSPARENT_HUGEPAGE in mm/huge_memory.c. So large folios depend on CONFIG_TRANSPARENT_HUGEPAGE instead of having a clean separation between functionality-to-support-PMD-mapping and functionality-to-support-order>0. So I preferred your earlier patch because it's more obvious. I mean, we could pull in the two or three patches from my tree that convert these functions and their callers to folios ... we're only at rc1. I can post them and see what others think.