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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 D0CD2C433E0 for ; Sat, 30 Jan 2021 01:28:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DD97A64E02 for ; Sat, 30 Jan 2021 01:28:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DD97A64E02 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 252538D0002; Fri, 29 Jan 2021 20:28:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2026D8D0001; Fri, 29 Jan 2021 20:28:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 140388D0002; Fri, 29 Jan 2021 20:28:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0215.hostedemail.com [216.40.44.215]) by kanga.kvack.org (Postfix) with ESMTP id F32348D0001 for ; Fri, 29 Jan 2021 20:28:55 -0500 (EST) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id B56BD2471 for ; Sat, 30 Jan 2021 01:28:55 +0000 (UTC) X-FDA: 77760707430.12.dust98_060b7d2275ad Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin12.hostedemail.com (Postfix) with ESMTP id 971FF18019A2F for ; Sat, 30 Jan 2021 01:28:55 +0000 (UTC) X-HE-Tag: dust98_060b7d2275ad X-Filterd-Recvd-Size: 2458 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf13.hostedemail.com (Postfix) with ESMTP for ; Sat, 30 Jan 2021 01:28:54 +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=SVX3ARdSFIEwAcuAAYtiaqWvVAmZeuZyPoPcxefhzBs=; b=U49SJjad/UkszN7hxgWUM33ktP m3P+d0eqvLTflteqCJNM6NfjcyfjMa6tV0GPv3dEeYOxoYeaKO94bwRqT1f1Qym+udjTsXLwO47bG NAd0SCWxyAnFMHV1tW0wMS5PIPhAEweUu5eZahU5MNHL2za2ataPUsXRgchhDmp4C2Y6zDJ5f/248 P312q+6jOyjLuNcSZFpM6vHuSzJCXiT+RWJarIwP8LraKLphEQDJlg1JTpxqVc2Pchl/IoaDGVTqR t3VV5Yip9A4vPUvjbaVz8ZN8bOoyVzs561rJEaichLWXRggrPqFl45vMpD0cGA2YqRiu/de6YedX+ L9ZjUU6w==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1l5f48-00AZIA-UI; Sat, 30 Jan 2021 01:28:45 +0000 Date: Sat, 30 Jan 2021 01:28:44 +0000 From: Matthew Wilcox To: Minchan Kim Cc: hughd@google.com, kirill@shutemov.name, linux-mm Subject: Re: THP handling with driver compound page on fault Message-ID: <20210130012844.GF308988@casper.infradead.org> References: <20210130010002.GE308988@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Fri, Jan 29, 2021 at 05:22:24PM -0800, Minchan Kim wrote: > Hi Mattew, > > On Sat, Jan 30, 2021 at 01:00:02AM +0000, Matthew Wilcox wrote: > > On Fri, Jan 29, 2021 at 04:13:07PM -0800, Minchan Kim wrote: > > > A custom driver overrides (vm_operations_struct.fault) and map their > > > compound page(__GFP_COMP) to page table on userprocess on demand. > > > > You're looking to backport: > > > > commit d01ac3c35214ce362f50cada37cb7bab8c801896 > > Author: Matthew Wilcox (Oracle) > > Date: Thu Oct 15 20:05:26 2020 -0700 > > > > mm/memory: remove page fault assumption of compound page size > > > > I guess you meant the check below. > > if (compound_order(page) != HPAGE_PMD_ORDER) > > What happens if driver allcoated HPAGE_PMD_ORDER size? ... then it should be fine to map it with a PMD entry?