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=-9.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,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 02A6FC47088 for ; Wed, 26 May 2021 22:29:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0CCD613BA for ; Wed, 26 May 2021 22:29:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234447AbhEZWbH (ORCPT ); Wed, 26 May 2021 18:31:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57608 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234201AbhEZWbG (ORCPT ); Wed, 26 May 2021 18:31:06 -0400 Received: from mail-pg1-x52f.google.com (mail-pg1-x52f.google.com [IPv6:2607:f8b0:4864:20::52f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5268DC061574 for ; Wed, 26 May 2021 15:29:33 -0700 (PDT) Received: by mail-pg1-x52f.google.com with SMTP id 27so2168482pgy.3 for ; Wed, 26 May 2021 15:29:33 -0700 (PDT) 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=qSkyuRLIywOgSpc4Exwi+hfwQCVFKBm/lXDqy5wmBnk=; b=r9U6b0w69kuX9cpBYYQ+ro++7IHUTvMcCWcpXHg3I+zP880ZXbtVedIaVGnN8MF00U dI/lELbxhOv7z5Pfz4Vd1ChrGE2Fa/nwR/Ezl2G97xJ9rktvrLCqRLVwvE5GkINly+gJ qNm0Zxm9QIIatcdkSC1WsBPjlDfifh2uOnjHwfQwmhLeHfo5yy9Pc3MVaXqW8IiEataS 04OQVyLN+yhwLzwLcG8As05euEReAkPUFGGOVQuwmS3VxF06AQXPfM8uiIiBR9Jy5oKm JxiJyj4tONmIcPn3lXFUMu8PAADi/f87anwdrLbZteg7tJUNj2YKgzGsZX/hjK3aVR5N XN4w== 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=qSkyuRLIywOgSpc4Exwi+hfwQCVFKBm/lXDqy5wmBnk=; b=Rm3L4VTcemRrjecN1XFVk+ikK2rSsSGVJYtwQNTvDmMW67sSKyqRRNCJu4z6uTUZVY lCuvXZevORdjERBcXUnnZLR2uDA32IxQNdNTp/1FhuyrEC6QeegudKxnzQfVVdomEmIE gX7QLYfCu/ldAbnrR6ANBcZm6mOjhOz53dbarRvtni6xL4e0+PpLYjpXgLVBUgt+eJqX uSKL9XgA8chRLhWfc4S5JIu3+OpkhB+xreKkK+0q+f+MtZsm7V7oaE+n47n8gV28aROJ FnDASg6P97ktpYNX12sY/N7DfB86UNzdB3DgJmHzzAiDBq9Wj/r0V8fKGtB0umLu6fSx Tfzw== X-Gm-Message-State: AOAM533n6YTfWaNGsZc+VAvfY7meYXTcBPhsub96MG2iHhSn83EK/axn VTkzCvKukymtSISAMD6awHE= X-Google-Smtp-Source: ABdhPJyhluupXGvNB3jQonGlCku2FVrdJ5z41FMGM97XET+rfk2B3/0QqgzoGEqd1TbHYVdBKJhKRA== X-Received: by 2002:a62:1496:0:b029:2e7:2674:147 with SMTP id 144-20020a6214960000b02902e726740147mr281572pfu.51.1622068172854; Wed, 26 May 2021 15:29:32 -0700 (PDT) Received: from google.com ([2620:15c:211:201:3dcc:6421:abe4:95d0]) by smtp.gmail.com with ESMTPSA id 4sm87124pgn.31.2021.05.26.15.29.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 May 2021 15:29:32 -0700 (PDT) Sender: Minchan Kim Date: Wed, 26 May 2021 15:29:30 -0700 From: Minchan Kim To: Yang Shi Cc: hughd@google.com, ziy@nvidia.com, kirill.shutemov@linux.intel.com, naoya.horiguchi@nec.com, wangyugui@e16-tech.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [v4 PATCH 2/2] mm: rmap: make try_to_unmap() void function Message-ID: References: <20210526201239.3351-1-shy828301@gmail.com> <20210526201239.3351-2-shy828301@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210526201239.3351-2-shy828301@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 26, 2021 at 01:12:39PM -0700, Yang Shi wrote: > Currently try_to_unmap() return bool value by checking page_mapcount(), > however this may return false positive since page_mapcount() doesn't > check all subpages of compound page. The total_mapcount() could be used > instead, but its cost is higher since it traverses all subpages. > > Actually the most callers of try_to_unmap() don't care about the > return value at all. So just need check if page is still mapped by > page_mapped() when necessary. And page_mapped() does bail out early > when it finds mapped subpage. > > Suggested-by: Hugh Dickins > Acked-by: Hugh Dickins > Signed-off-by: Yang Shi Acked-by: Minchan Kim Thanks for the update, Yang Shi.