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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 AB469C4338F for ; Wed, 4 Aug 2021 14:22:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5E82260F25 for ; Wed, 4 Aug 2021 14:22:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5E82260F25 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=shutemov.name Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id B31F98D0003; Wed, 4 Aug 2021 10:22:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AE1618D0001; Wed, 4 Aug 2021 10:22:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9D0F18D0003; Wed, 4 Aug 2021 10:22:55 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0112.hostedemail.com [216.40.44.112]) by kanga.kvack.org (Postfix) with ESMTP id 86DAD8D0001 for ; Wed, 4 Aug 2021 10:22:55 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 2D50C252B8 for ; Wed, 4 Aug 2021 14:22:55 +0000 (UTC) X-FDA: 78437614710.03.FB53B00 Received: from mail-lf1-f47.google.com (mail-lf1-f47.google.com [209.85.167.47]) by imf25.hostedemail.com (Postfix) with ESMTP id D6C8EB000E33 for ; Wed, 4 Aug 2021 14:22:54 +0000 (UTC) Received: by mail-lf1-f47.google.com with SMTP id t9so4761062lfc.6 for ; Wed, 04 Aug 2021 07:22:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=RWlPdL6DwUB6mJRKo0+xi01KggPqUO2/jhQbASI+2FE=; b=QE89PTFODc67XC5H0kcbNIHy9cHlhvZkaAEzK2h6T5fIoEU3d/4E71kndL/f8s0tX+ JJ2IIyqzYAV0j2e/4ewwAvS4XIxTlCfeK/XRJ/YxRCkeu+mNPzOr1xke1fPqRbdyAR4B HpxGTKCP36gIfxXsUcVm/lgcHiih0hCBskkrIwgV3F6DfSmJA40eJiRToQYPcUYR0eyT RCbPpYju7Y4YRRRqtxU07ogL97sP0o4V1NsUx2pYjrfcgP0VetrNVpj/ytQszajPV9MH 6wty0FiHYQ32pTJpHGrmLfDORsARUr2M1ZV8qaW76tJn4/ZHo3J7Cc8u8NvjL/6y+gTn ZYpQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=RWlPdL6DwUB6mJRKo0+xi01KggPqUO2/jhQbASI+2FE=; b=cLRBvopKOmtdiHVcCVeraf4JVAvsdG8vup0GqZTOYwknve2f7iz5E7VGuKBe7uq+1W nYkKXwpvL1dvOrJIbN+gj+boziuwoGSHwvEtq+q6cRS7IjDhjo+U+1XHN2SPRFAXdaf5 AZF+4dE0aJzcRQ2aK3cyq79qZGXH5d3u0SelewMtuE+eSjfW/zIlWyYYYJES4xa2SC9F VYOS5sV2RoGhOo8ga7tm3BonTvJ5V4AEMQEw1rFrfgq9YCy2PPpbTuVWDIFNMyb3mhDy qe9m2Zy7Ni23rPLhf57dhorAcaY2ZKijueb3JpDD/gCuOYXUDe04w7OA3XZ0Gw4j3v+3 ZiiA== X-Gm-Message-State: AOAM530kgpFjSjWBvcrJ190cKSHNWCqJJ0qAZQMkkl40OhKFH6M4eQuS 657ZhdoIcrm71tkm8AjOI5RJEA== X-Google-Smtp-Source: ABdhPJwmL8YC08a1GHI5b6vVSDE4TmS9HGaEeEH0JAy+4KfiRyfMQ4fATRlflfmdnGgIK/c1Hjc6kw== X-Received: by 2002:a05:6512:3481:: with SMTP id v1mr3277279lfr.325.1628086973453; Wed, 04 Aug 2021 07:22:53 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id o10sm211359lfl.129.2021.08.04.07.22.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Aug 2021 07:22:52 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 00CD6102BC1; Wed, 4 Aug 2021 17:22:57 +0300 (+03) Date: Wed, 4 Aug 2021 17:22:57 +0300 From: "Kirill A. Shutemov" To: Yu Zhao Cc: linux-mm@kvack.org, Andrew Morton , Hugh Dickins , "Kirill A . Shutemov" , Matthew Wilcox , Vlastimil Babka , Yang Shi , Zi Yan , linux-kernel@vger.kernel.org, Shuang Zhai Subject: Re: [PATCH 2/3] mm: free zapped tail pages when splitting isolated thp Message-ID: <20210804142257.tsgzpfc3zq7um7iu@box.shutemov.name> References: <20210731063938.1391602-1-yuzhao@google.com> <20210731063938.1391602-3-yuzhao@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210731063938.1391602-3-yuzhao@google.com> Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=shutemov-name.20150623.gappssmtp.com header.s=20150623 header.b=QE89PTFO; spf=none (imf25.hostedemail.com: domain of kirill@shutemov.name has no SPF policy when checking 209.85.167.47) smtp.mailfrom=kirill@shutemov.name; dmarc=none X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D6C8EB000E33 X-Stat-Signature: otqmczo3p3xk4m3qi8ptx8i73bxr316o X-HE-Tag: 1628086974-663588 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 Sat, Jul 31, 2021 at 12:39:37AM -0600, Yu Zhao wrote: > @@ -2506,6 +2508,25 @@ static void __split_huge_page(struct page *page, struct list_head *list, > continue; > unlock_page(subpage); > > + /* > + * If a tail page has only two references left, one inherited > + * from the isolation of its head and the other from > + * lru_add_page_tail() which we are about to drop, it means this > + * tail page was concurrently zapped. Then we can safely free it > + * and save page reclaim or migration the trouble of trying it. > + */ > + if (list && page_ref_freeze(subpage, 2)) { > + VM_BUG_ON_PAGE(PageLRU(subpage), subpage); > + VM_BUG_ON_PAGE(PageCompound(subpage), subpage); > + VM_BUG_ON_PAGE(page_mapped(subpage), subpage); > + > + ClearPageActive(subpage); > + ClearPageUnevictable(subpage); Why touch PG_Active/PG_Unevictable? > + list_move(&subpage->lru, &pages_to_free); > + nr_pages_to_free++; > + continue; > + } > + -- Kirill A. Shutemov