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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 92206C43331 for ; Sat, 28 Mar 2020 00:20:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 66C11206F2 for ; Sat, 28 Mar 2020 00:20:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="uTMKkCv4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727070AbgC1AUm (ORCPT ); Fri, 27 Mar 2020 20:20:42 -0400 Received: from mail-lf1-f65.google.com ([209.85.167.65]:35457 "EHLO mail-lf1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726212AbgC1AUl (ORCPT ); Fri, 27 Mar 2020 20:20:41 -0400 Received: by mail-lf1-f65.google.com with SMTP id t16so8501572lfl.2 for ; Fri, 27 Mar 2020 17:20:38 -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=/PGvAdlDpTAvB7KdpnM6fLatQ14ogwNqTHuTCTj8vrc=; b=uTMKkCv4mPz+vxre39ZpG3ohbpZ1KSoepLIPrRvYKRYwR9XSD/vNYjdkqMT4BRGGjU 9kwBn0UH+Ms6hId660N1sBAHuAPWxzAWeugMJAHkFjWNNdtOpgD98XeKD5LVPJf2Q5pL TpDAqUaxR9EzteQ6zOn+BhK0CDJZc+PY5FWWFd6yZZVAx1ndv2/sSaUITY4D1b4ycADF jcFAZvwzA96l/3pHOnviyMV1atk9eVoMtI/kdtsZ+Juy2X0/uo6zUVVtt2cu4gkMSF8i wLs61ABuzTLDxQN5Q9YnxeGJa0Bc5y2K2ThKrRD8EUC2nXQx2EXKVqFuPP6zo73fuvw+ dnlw== 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=/PGvAdlDpTAvB7KdpnM6fLatQ14ogwNqTHuTCTj8vrc=; b=NH814w7VtaQ8L7LXapi0yVVToQd43GeIjbkAD4hSVMw9byvXQdZcDdAlmemJ1lvOQX O3aEOFn/GYrVHlx7abxS9AFmYthXNB3Tq9PzEwdfOxYQcoJ4U4dffsOnjqKpLo8bwKpA CZU7kTHjXGx/HsWHKB+M4yLlw6cQBBjO2nLa+8dnkSXP3o7xmJlG3yI6bkGNmXoNciwT zsEUpQVjfEgfATEdLZDcSU/f2eK7iXFRS+TH7l+jRBjXNV84KOxs1oNwSoAGWmirbvIx aFDQYe35A8p5fgB5yo0uQ+owN2b8hQ8VEbLxabgRKWjLdWcA5M4eCEPb9UU8XRMUJg5T kDGw== X-Gm-Message-State: AGi0PuYn2iCQe8BIccokU+YJkzEAeRetuw1NZWEA9qy6vFCH5500k8M4 oNeNwANb2GLV2ZUV4ZaA0DmleA== X-Google-Smtp-Source: APiQypI1dzxazGJf2mdV8Y25k+HN8OAvP36U5psGaYtZEqO0MsDmIh5lsZTOXJ7ykFOGzeBdPWB0fQ== X-Received: by 2002:a19:6445:: with SMTP id b5mr1052563lfj.187.1585354837656; Fri, 27 Mar 2020 17:20:37 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id h10sm3570540lfc.42.2020.03.27.17.20.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Mar 2020 17:20:36 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 62DE3100D24; Sat, 28 Mar 2020 03:20:41 +0300 (+03) Date: Sat, 28 Mar 2020 03:20:41 +0300 From: "Kirill A. Shutemov" To: Zi Yan Cc: akpm@linux-foundation.org, Andrea Arcangeli , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: Re: [PATCH 3/7] khugepaged: Drain LRU add pagevec to get rid of extra pins Message-ID: <20200328002041.5tnoy67ruw7lavwx@box> References: <20200327170601.18563-1-kirill.shutemov@linux.intel.com> <20200327170601.18563-4-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 27, 2020 at 01:34:20PM -0400, Zi Yan wrote: > On 27 Mar 2020, at 13:05, Kirill A. Shutemov wrote: > > > __collapse_huge_page_isolate() may fail due to extra pin in the LRU add > > pagevec. It's petty common for swapin case: we swap in pages just to > > fail due to the extra pin. > > > > Signed-off-by: Kirill A. Shutemov > > --- > > mm/khugepaged.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > > index 14d7afc90786..39e0994abeb8 100644 > > --- a/mm/khugepaged.c > > +++ b/mm/khugepaged.c > > @@ -585,11 +585,19 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, > > * The page must only be referenced by the scanned process > > * and page swap cache. > > */ > > + if (page_count(page) != 1 + PageSwapCache(page)) { > > + /* > > + * Drain pagevec and retry just in case we can get rid > > + * of the extra pin, like in swapin case. > > + */ > > + lru_add_drain(); > > + } > > if (page_count(page) != 1 + PageSwapCache(page)) { > > unlock_page(page); > > result = SCAN_PAGE_COUNT; > > goto out; > > } > > + > > if (pte_write(pteval)) { > > writable = true; > > } else { > > -- > > 2.26.0 > > Looks good to me. Is the added empty line intentional? Yes. It groups try and retry together. -- Kirill A. Shutemov