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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 25E67C433DB for ; Sat, 30 Jan 2021 01:49:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 81AAA64E00 for ; Sat, 30 Jan 2021 01:49:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 81AAA64E00 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B6BDB8D0002; Fri, 29 Jan 2021 20:49:16 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AF4F08D0001; Fri, 29 Jan 2021 20:49:16 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9BC1A8D0002; Fri, 29 Jan 2021 20:49:16 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0038.hostedemail.com [216.40.44.38]) by kanga.kvack.org (Postfix) with ESMTP id 8206F8D0001 for ; Fri, 29 Jan 2021 20:49:16 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 37F0D180AD837 for ; Sat, 30 Jan 2021 01:49:16 +0000 (UTC) X-FDA: 77760758712.21.group45_601329f275ad Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin21.hostedemail.com (Postfix) with ESMTP id 1F90A180442D3 for ; Sat, 30 Jan 2021 01:49:16 +0000 (UTC) X-HE-Tag: group45_601329f275ad X-Filterd-Recvd-Size: 4180 Received: from mail-pg1-f176.google.com (mail-pg1-f176.google.com [209.85.215.176]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Sat, 30 Jan 2021 01:49:15 +0000 (UTC) Received: by mail-pg1-f176.google.com with SMTP id i7so7820845pgc.8 for ; Fri, 29 Jan 2021 17:49:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=7No8scn7gnbsRUcfGwWcGJYIeN5Tri/u18/P1/Ox2Ws=; b=MJrehQTFts7++k5WPBgj5HQ09Xe3QfzvzV4xw1XYM+r+JIi31Vi4JoDKk7F1qSHz9I KNYIBhEni1npXmJVpUw1ux/LL2oW+l3dlclzFF+mTAWHsMWhPE1yLax0Rzp0hQHn3FBs qwnURN/odnLPDGbmVYmEJ/dkTJf/hLMtUpHGBjW12SfjHmgEif34qQWae6hajgZYFgie pnwLZt1cGWddVFyl/VgsUlx8nJEUBMrNCceNmAvnjlk5Jk21NlWJtGT9tn/r/9dC/hKS jLFdp9YL8giduDHLNNz6drCh04FcrnNVD9i2YaPtAuvpWWcHZZLXHwc+9uaWomi4nflS aZLQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=7No8scn7gnbsRUcfGwWcGJYIeN5Tri/u18/P1/Ox2Ws=; b=qncS+dqtI3Qekc03nSBW+nBMrZ7GertW7MtkJHogv57dxqoDoiLm7UPfAm29F57t/B 5a6XT1nc6q1anclfVDrgOtiW3eMJBebkG/fKdnitdwHxDEPTlDTu0Wh1ryFGsXrmYrnu TaWeVeP3J58m4FHM0VEI8qsuyUxylgE3OHkrMGDY3SDCGxv0UoeVBnESHrEBoWRg19sj 5iecLrIchQpOIXQHI/m56u3YJbkTAjxRgHx9oL5KBlwSGeepDFlbIU1f7xWTTGmKKO9U GFyyaJfLEKfuVMwAK9jVmLIcyeE+Z94GZ6r/V1Tx5Mn3DlsBa94DzlqLr20i6FRdzf0T ec+A== X-Gm-Message-State: AOAM533DRor6yg91cKrjuB16r3J2NW/Rm+K7/WDgQG2WylATP2JZhnW4 9ZyctJA/3FLtHqboS18yjhA= X-Google-Smtp-Source: ABdhPJxjJvVYd6Uvl14Zlau3zbRVWtfQapAvD+yADnMKdd9GM8dEpG9s/8oAcrcQPMM02lS985CHJQ== X-Received: by 2002:a63:4e08:: with SMTP id c8mr6930348pgb.87.1611971354775; Fri, 29 Jan 2021 17:49:14 -0800 (PST) Received: from google.com ([2620:15c:211:201:b81c:be0c:d615:b5bb]) by smtp.gmail.com with ESMTPSA id y11sm9921310pff.93.2021.01.29.17.49.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Jan 2021 17:49:13 -0800 (PST) Date: Fri, 29 Jan 2021 17:49:11 -0800 From: Minchan Kim To: Matthew Wilcox Cc: hughd@google.com, kirill@shutemov.name, linux-mm Subject: Re: THP handling with driver compound page on fault Message-ID: References: <20210130010002.GE308988@casper.infradead.org> <20210130012844.GF308988@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210130012844.GF308988@casper.infradead.org> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000005, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Jan 30, 2021 at 01:28:44AM +0000, Matthew Wilcox wrote: > 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? I don't think so because following logic assumes it's THP page, for example, page_add_file_rmap, count_vm_event(THP_FILE_MAPPED) in do_set_pmd. Isn't it bug?