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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=ham 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 1597AC48BE6 for ; Sat, 12 Jun 2021 03:14:59 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A1536611CB for ; Sat, 12 Jun 2021 03:14:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A1536611CB Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D47636B006C; Fri, 11 Jun 2021 23:14:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D1E726B006E; Fri, 11 Jun 2021 23:14:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BE6B06B0070; Fri, 11 Jun 2021 23:14:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0247.hostedemail.com [216.40.44.247]) by kanga.kvack.org (Postfix) with ESMTP id 8C05C6B006C for ; Fri, 11 Jun 2021 23:14:57 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 24A07D21E for ; Sat, 12 Jun 2021 03:14:57 +0000 (UTC) X-FDA: 78243605034.10.CC926C7 Received: from mail-wm1-f41.google.com (mail-wm1-f41.google.com [209.85.128.41]) by imf10.hostedemail.com (Postfix) with ESMTP id 20A3741449E4 for ; Sat, 12 Jun 2021 03:14:50 +0000 (UTC) Received: by mail-wm1-f41.google.com with SMTP id u5-20020a7bc0450000b02901480e40338bso7060237wmc.1 for ; Fri, 11 Jun 2021 20:14:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=QzKLoZIh4OHZevy8jEH3FdJdgbtT1lGHJS8+XMd4ma0=; b=VAFEtCgqoxFGFrAAgAsdV8gLrHMwQxCnneJXRfBuQ5Qm+dMKxPfTW6gA4/cl35h7fQ xx+EWkn/X6r6gb85mJa8fQnGr4HSCYIZu6UoxbRslVitP6kz35LvNMMRuAEVQVav3AN+ Lyo4Dox441LruuFytDWhvvwtiJCyux9tY9JSAYENjx9NrdCHCk6ppAmcAMWQXcox7gQ1 n5IeJC08AC//QX0mCczs0M6m4yjCYPuKIVvYtRxwV9YsbgCavcxA/svYyQzuf76N4kkL 7zC+P77Tg+4MxlqSWRAJ8af/UjHrM3J7ZGZAG4MWLlORmLMCpBxFMHTknkkXnt9WCiBx fzAw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=QzKLoZIh4OHZevy8jEH3FdJdgbtT1lGHJS8+XMd4ma0=; b=HjeVCQ+xTNAzihgdQRxiLEXpjW8qOfmaAr/KBj82VhXUSFwiZXXRmmzwk2JAAOgUN4 o6DWOP+rbgLWGJk5s2D0QKD9A1vUJePrA9B2QrrBcZErPcbA6dVkqUlcgHKrodg+W0R/ +JEjs7NbxWd2QSDaZjh5hE0A/OX9JWa1haCTvy+WL6BRzgb2x8zj7PN/ZXQTzRNSO1mQ rzTVsQI6Ugl2Q1Jmjr+5wK27/Wdwu69gHvrGIbj6F2OudqOGmjild6d1kCPaX48cUkB2 /Q3c677ludC6uagBhjtaqIYw9uYudIFpNIXhLWsVOJ/yJ61hAFyeQWWYtfDn/o79N2Jk RmWA== X-Gm-Message-State: AOAM533OIicS4YpKgb2CXx4YGTR6jEMKyKnTjPlQZmHPh9JVdBlBQ5Ey vbGkF4/7f+k+4iGlELLufncTvDfginlTJ94Gw8oeWw== X-Google-Smtp-Source: ABdhPJzDn74wI0l4Z2zmaL4Y3vFY4CupItNzd5V1v5tk/Nu7rNH81IG3xLSH/Fii1p4cwCaItHJza8mSVgYKKgTaEX0= X-Received: by 2002:a05:600c:3647:: with SMTP id y7mr23191792wmq.149.1623467695416; Fri, 11 Jun 2021 20:14:55 -0700 (PDT) MIME-Version: 1.0 References: <20210612000714.775825-1-willy@infradead.org> In-Reply-To: <20210612000714.775825-1-willy@infradead.org> From: Yu Zhao Date: Fri, 11 Jun 2021 21:14:43 -0600 Message-ID: Subject: Re: [PATCH] mm: Mark idle page tracking as BROKEN To: "Matthew Wilcox (Oracle)" Cc: akpm@linuxfoundation.org, Linux-MM , Heiko Carstens , Rafael Aquini , Vlastimil Babka , Vladimir Davydov , "Kirill A . Shutemov" Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=google.com header.s=20161025 header.b=VAFEtCgq; spf=pass (imf10.hostedemail.com: domain of yuzhao@google.com designates 209.85.128.41 as permitted sender) smtp.mailfrom=yuzhao@google.com; dmarc=pass (policy=reject) header.from=google.com X-Stat-Signature: k5hybg3fpgeixhau79y5xjifbdko3n3e X-Rspamd-Queue-Id: 20A3741449E4 X-Rspamd-Server: rspam06 X-HE-Tag: 1623467690-428410 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, Jun 11, 2021 at 6:08 PM Matthew Wilcox (Oracle) wrote: > > In discussion with other MM developers around how idle page tracking > should be fixed for transparent huge pages, several expressed the opinion > that it should be removed as it is inefficient at accomplishing the > job that it is supposed to, and we have better mechanisms (eg uffd) for > accomplishing the same goals these days. > > Mark the feature as BROKEN for now and we can remove it entirely in a > few months if nobody complains. It is not enabled by Android, ChromeOS, > Debian, Fedora or SUSE. Red Hat enabled it with RHEL-8.1 and UEK followed > suit, but I have been unable to find why RHEL enabled it. > > Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Yu Zhao It had been broken on arm64 (corrupting user data) until commit 07509e10dcc7 ("arm64: pgtable: Fix pte_accessible()") came along. It may also break functions that call pte/pmd_mkold() but not test_and_clear_young(), e.g., it breaks MADV_FREE because page_referenced() will return true upon seeing PageYoung(), which in turn makes the page reclaim reject the madvise()'ed pages. > --- > mm/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/Kconfig b/mm/Kconfig > index 02d44e3420f5..311b50bb92ce 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -772,7 +772,7 @@ config DEFERRED_STRUCT_PAGE_INIT > > config IDLE_PAGE_TRACKING > bool "Enable idle page tracking" > - depends on SYSFS && MMU > + depends on SYSFS && MMU && BROKEN > select PAGE_EXTENSION if !64BIT > help > This feature allows to estimate the amount of user pages that have > -- > 2.30.2 > >