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=-3.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 971ADC433DB for ; Mon, 21 Dec 2020 18:36:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B361230FC for ; Mon, 21 Dec 2020 18:36:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726864AbgLUSf7 (ORCPT ); Mon, 21 Dec 2020 13:35:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726648AbgLUSf7 (ORCPT ); Mon, 21 Dec 2020 13:35:59 -0500 Received: from mail-il1-x12f.google.com (mail-il1-x12f.google.com [IPv6:2607:f8b0:4864:20::12f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 07E12C061282 for ; Mon, 21 Dec 2020 10:35:19 -0800 (PST) Received: by mail-il1-x12f.google.com with SMTP id 75so9715252ilv.13 for ; Mon, 21 Dec 2020 10:35:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=YliUtlY76/UIPuQ5v8deFXxZeb8eSvRLcMxme2JxEEk=; b=HDksKqgKauZN6tvbdPBgggj8IeeTS2c7JRuSWMI+pRG1FwKAhMCJxMCv7JOIqk50wv 3X1HRLkpEKIsTmGLQK6vIyf/RMl8sqUJoc0+IVGVdkvPNiQkOjCyDbUhahzYluorDnrk 1PDsuxVXgwT/JnDR/e8fyiqWr/gjcp4gXGi2ngqD9bS5/EBS76qfZPKMvDBaRcXFxHGt YOSyX7QbQ/Koym0Jms6BgoWpgnw/5heVHu2j7+FeQsRTUWVZEWILea7Byq/nnV5Cq6bO YDDYicvRlZMY5s2D5oa9p6I/4Nwjhwv9qDpErWN/14vrvlkMgsgZNqe/YH2kcc3Fnt+d 1eOw== 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=YliUtlY76/UIPuQ5v8deFXxZeb8eSvRLcMxme2JxEEk=; b=TvZpAje5HGbVJLznW3sA/nWNZFJJvBEjRjmV3cFs/kqdGwPuH1UW8ppsQE4wiLlKga ZifD4ii298eq406vfZU7XkuGDdQJ7a7YpVOOXR37UBwy4IPz9F4m1HComDb2xLo5V94R TZRgPdDQfrUgaXP4bdk5fLgmvu6zghNXqW0eG2ZjKxMc+7Uw+mknyyD/HreirsbaQbkU CiiajQzeKELRDlyNuy3/dM+/xbHOl6bNYCz2UPhgPWPr+JPiO/okC501/AosV7ZNo+1T Myn9aA9jdAg3AfQ3NOdlZ9Z6/RUtiyZDSEDqcTsfpm3Hl10Nqp9833uP3DGAqLDoJ6PY mFCg== X-Gm-Message-State: AOAM530fShi9NHZNzovy9WvjTPMMUckSVkRmUZHqh4q6d3VKXLriRM5s hnw1RrlhwAeJ8d7X73cgXFeahFE+HtI3nF6RQELENvFQHOBdK9Td X-Google-Smtp-Source: ABdhPJxKT6tC6/ndV2N5i1FwKZxN3yOMknKcMYRbpSq6pVUOWTKpPSP2SnmFD7tg+Np8Z6fWmUqBTLjQBM+VPNs1bYw= X-Received: by 2002:a63:480f:: with SMTP id v15mr2249541pga.341.1608565986866; Mon, 21 Dec 2020 07:53:06 -0800 (PST) MIME-Version: 1.0 References: <20201217121303.13386-1-songmuchun@bytedance.com> <20201217121303.13386-4-songmuchun@bytedance.com> <20201221091123.GB14343@linux> <20201221134345.GA19324@linux> In-Reply-To: <20201221134345.GA19324@linux> From: Muchun Song Date: Mon, 21 Dec 2020 23:52:30 +0800 Message-ID: Subject: Re: [External] Re: [PATCH v10 03/11] mm/hugetlb: Free the vmemmap pages associated with each HugeTLB page To: Oscar Salvador Cc: Jonathan Corbet , Mike Kravetz , Thomas Gleixner , mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, Peter Zijlstra , viro@zeniv.linux.org.uk, Andrew Morton , paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, Randy Dunlap , oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, Mina Almasry , David Rientjes , Matthew Wilcox , Michal Hocko , "Song Bao Hua (Barry Song)" , David Hildenbrand , naoya.horiguchi@nec.com, Xiongchun duan , linux-doc@vger.kernel.org, LKML , Linux Memory Management List , linux-fsdevel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Dec 21, 2020 at 9:44 PM Oscar Salvador wrote: > > On Mon, Dec 21, 2020 at 07:25:15PM +0800, Muchun Song wrote: > > > Should we add a BUG_ON in vmemmap_remap_free() for now? > > > > BUG_ON(reuse != start + PAGE_SIZE); > > I do not think we have to, plus we would be BUG_ing for some specific use > case in "generic" function. The vmemmap_remap_range() walks page table range [start, end), if reuse is equal to (start + PAGE_SIZE), the range can adjust to [start - PAGE_SIZE, end). But if not, we need some work to implement the "generic" function. - adjust range to [min(start, reuse), end) and call vmemmap_remap_rangeand which skip the hole which is [reuse + PAGE_SIZE, start) or [end, reuse). - call vmemmap_remap_range(reuse, reuse + PAGE_SIZE) to get the reuse page.Then, call vmemmap_remap_range(start, end) again to remap. Which one do you prefer? > Maybe others think different though. > > -- > Oscar Salvador > SUSE L3 -- Yours, Muchun