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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 6BCF3C433DB for ; Tue, 5 Jan 2021 18:04:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 05E7422CB3 for ; Tue, 5 Jan 2021 18:04:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 05E7422CB3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 529C98D008B; Tue, 5 Jan 2021 13:04:28 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4D8F08D006E; Tue, 5 Jan 2021 13:04:28 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3EEF68D008B; Tue, 5 Jan 2021 13:04:28 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0004.hostedemail.com [216.40.44.4]) by kanga.kvack.org (Postfix) with ESMTP id 25E638D006E for ; Tue, 5 Jan 2021 13:04:28 -0500 (EST) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id C25843624 for ; Tue, 5 Jan 2021 18:04:27 +0000 (UTC) X-FDA: 77672496174.11.screw52_4716a62274da Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin11.hostedemail.com (Postfix) with ESMTP id 9E306180F8B80 for ; Tue, 5 Jan 2021 18:04:27 +0000 (UTC) X-HE-Tag: screw52_4716a62274da X-Filterd-Recvd-Size: 4223 Received: from mail-ed1-f50.google.com (mail-ed1-f50.google.com [209.85.208.50]) by imf17.hostedemail.com (Postfix) with ESMTP for ; Tue, 5 Jan 2021 18:04:27 +0000 (UTC) Received: by mail-ed1-f50.google.com with SMTP id cm17so1572635edb.4 for ; Tue, 05 Jan 2021 10:04:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=g9dWEenEa1Tbu2wF3XZKdyzz1Vq1iEFWmTgkC1pdmgE=; b=gbHxkwq9CjvYKdpKPtd2ZRrJEAevgMtRmYOb22xACgeJQuGsT2kP/c6aINE2iyvqDh tdJH1JdM40naCrddYIyMiMsUENx53xvhNMADzgLohYngGBuX0McumeV6/7gbDztyy67e oWl8U90wipDPcVTOylJwuJSgvaDFkudEhEdKy0z85h+dvWIYq7TwqJjK1ZliE9r37x/P Nf4fANZwZ4WLBw5I2MbWU9tvHHR6hqLH2dvzrurTCXvRUtgJojsDVF1GeWEzRPdTR+Gp hOIQ3Is353X0KpdkYQhw8Amkqx+8xBUZcDw1Zb4JxHmT1787wDciaHU+koprkXTiO/cc LzWA== 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=g9dWEenEa1Tbu2wF3XZKdyzz1Vq1iEFWmTgkC1pdmgE=; b=e4r0Itsxr+Jgka+tFGWKRUmkdwsWQtpYU7PtGXaN4QrZCFFosR6+Mkfnbo1XuBI3FT 2KRJByDUtcqkuVvjaEPMmYsKrbtHHmY9IAauIAbWq2+Z2zLltpFYz+GBKLQitXlwJl2S EfU+ctcrYhkhiSfv1KlNxMOnXonZRXlQxA5c02CT/HeTV/e7Nsf3WSMiUclQNIiHmcf5 NvdJGiTx8VbF0EXRTZqcrNoM3yaQeBd8XxL0FAlaIRdpMYjirGAsvPfazX123VI5BnXW drxYLYTzOu1q6r83oF7aDPfYvkyBn3M7D2Bf/A5IoVSeavYH1G9t7tyuhHvF1p4lEsOr 99NA== X-Gm-Message-State: AOAM5311A7g0JWXvuF1yOTRD73/8ESymFhivJB6c4LnX5a4HsDgFwaTS yDg+uVSdA+/roNIVrb0tkEqiU+zmPRyPeQLQfKU= X-Google-Smtp-Source: ABdhPJy2q8y1vT9nVv1PXe/O7TiK+riynHFEQmh3eJty2cejYpnhb5xJ60LuQuiK08rsZfPpjTkqH1DQnwPYWgp75Ss= X-Received: by 2002:a05:6402:ca2:: with SMTP id cn2mr956808edb.137.1609869865933; Tue, 05 Jan 2021 10:04:25 -0800 (PST) MIME-Version: 1.0 References: <20210104065843.5658-1-songmuchun@bytedance.com> In-Reply-To: From: Yang Shi Date: Tue, 5 Jan 2021 10:04:13 -0800 Message-ID: Subject: Re: [PATCH 1/6] mm: migrate: do not migrate HugeTLB page whose refcount is one To: David Hildenbrand Cc: Muchun Song , Mike Kravetz , Andrew Morton , hillf.zj@alibaba-inc.com, Naoya Horiguchi , ak@linux.intel.com, yongjun_wei@trendmicro.com.cn, mhocko@suse.cz, Linux MM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" 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 Tue, Jan 5, 2021 at 8:58 AM David Hildenbrand wrote: > > On 04.01.21 07:58, Muchun Song wrote: > > If the refcount is one when it is migrated, it means that the page > > was freed from under us. So we are done and do not need to migrate. > > > > Signed-off-by: Muchun Song > > --- > > mm/migrate.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/mm/migrate.c b/mm/migrate.c > > index 4385f2fb5d18..a6631c4eb6a6 100644 > > --- a/mm/migrate.c > > +++ b/mm/migrate.c > > @@ -1279,6 +1279,12 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, > > return -ENOSYS; > > } > > > > + if (page_count(hpage) == 1) { > > + /* page was freed from under us. So we are done. */ > > + putback_active_hugepage(hpage); > > + return MIGRATEPAGE_SUCCESS; > > + } > > + > > new_hpage = get_new_page(hpage, private); > > if (!new_hpage) > > return -ENOMEM; > > > > This series seems to fix quite some important cases (thanks). Do we want > to cc stable some/all? For this particular one, I don't think so IMHO. It is an optimization rather than a bug fix. > > -- > Thanks, > > David / dhildenb > >