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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6AAA3C6FA8E for ; Thu, 2 Mar 2023 13:58:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229566AbjCBN6J (ORCPT ); Thu, 2 Mar 2023 08:58:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229456AbjCBN6G (ORCPT ); Thu, 2 Mar 2023 08:58:06 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AD4C4E0 for ; Thu, 2 Mar 2023 05:57:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1677765437; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=gccvmUWslfjTlAzcdDHC7/3ANajeBrFuvt3rIaFYx8Y=; b=bMOVttF7ni/XtkPEh1qixRR8/VTPRJFv2foQRwBR7NWs7NPKlR/iig39m6wIeqG1rppwYu MCeYS8e2Jde2pRa1j4l7u/3A059F0RtNJhgrgR0bsjAu7h8+ywexQoKUrbvm2E5D5z0b2N DqT4ntICympQe3snn+NOqkEwt3hJ9P4= Received: from mail-qv1-f72.google.com (mail-qv1-f72.google.com [209.85.219.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-318-EsgGfzxKOpGRYeY8EMBhZw-1; Thu, 02 Mar 2023 08:57:16 -0500 X-MC-Unique: EsgGfzxKOpGRYeY8EMBhZw-1 Received: by mail-qv1-f72.google.com with SMTP id ef20-20020a0562140a7400b004c72d0e92bcso8782461qvb.12 for ; Thu, 02 Mar 2023 05:57:16 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1677765435; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=gccvmUWslfjTlAzcdDHC7/3ANajeBrFuvt3rIaFYx8Y=; b=W239mK6yihV2jF1TbFcSzbgwILL0hZrReIKRBIQxfkJ0VJGceW9i8mmZw2wuL6952X gAZM8XS+VqZpjM6fwlPvrvFRRBWZixMtezskAZklCV36Pxry2SknMKSOYzuFai1oA9mc JTqEXoMSfjsv3rF3SDSTfHJCGxhu34Bbz4+GOgwthFcCFegkHwDfn9nlL4ZqHQQu6LwO E0d7pwxvmEfXD9wBWYStwo9TNICMQaNMDMqqbfzQ6BuLjO1ofU03AmEW4EBFYKZ40e5o zD2UHiLKAmIoPm5KmVIt0vgVJWUaCDRSl7NAxsByLpgVdgFg8SEoZvitmqN9VVfzBvtl qugg== X-Gm-Message-State: AO0yUKUCSPLVHEIie8J7YHAvuwuG7+AYRB+oi2pIAsZ9OMsSM5ez1Vfq oZtujP/S7qAGvshOr01p4x0ZiH8YhcBVysWCuRWbZcrz0D6I0OCvkouZVRUvyMMFacohV7f2cP5 Ox3rxufyjDWfSUfFDZ4qm82lPFRA75A== X-Received: by 2002:ac8:7f0a:0:b0:3b8:695b:aad1 with SMTP id f10-20020ac87f0a000000b003b8695baad1mr20143122qtk.1.1677765435575; Thu, 02 Mar 2023 05:57:15 -0800 (PST) X-Google-Smtp-Source: AK7set8H4gfBuJJp5phRpbP5qGIlqmNyZirFO7rBLz5iR3KfJfdBtCXIKEdIK9pXyEDSVuBmAby7dQ== X-Received: by 2002:ac8:7f0a:0:b0:3b8:695b:aad1 with SMTP id f10-20020ac87f0a000000b003b8695baad1mr20143082qtk.1.1677765435194; Thu, 02 Mar 2023 05:57:15 -0800 (PST) Received: from x1n (bras-base-aurron9127w-grc-56-70-30-145-63.dsl.bell.ca. [70.30.145.63]) by smtp.gmail.com with ESMTPSA id d71-20020ae9ef4a000000b0073ba3fd4e4asm10972473qkg.16.2023.03.02.05.57.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Mar 2023 05:57:14 -0800 (PST) Date: Thu, 2 Mar 2023 08:57:13 -0500 From: Peter Xu To: David Hildenbrand Cc: Muhammad Usama Anjum , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrea Arcangeli , Andrew Morton , Mike Rapoport , Axel Rasmussen , Nadav Amit , "kernel@collabora.com" Subject: Re: [PATCH v2] mm/uffd: UFFD_FEATURE_WP_UNPOPULATED Message-ID: References: <20230227230044.1596744-1-peterx@redhat.com> <640319be-ddb6-d74f-b731-eee5ceab3d01@collabora.com> <8783f47e-76ea-cd24-e373-f2156884cd05@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8783f47e-76ea-cd24-e373-f2156884cd05@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 02, 2023 at 10:37:44AM +0100, David Hildenbrand wrote: > Especially for such large sparse VMAs, the current way of allocating > pagetables to place markers/zeropages is far from optimal. IMHO that's not a generic workload. As mentioned in the reply there, I would suggest we go with simple then we have space to optimize it in the future if necessary, because the API will be the same. If I want to monitor a super sparse VMA on dirty, one thing I can already try is register with MISSING + WP (!WP_UNPOPULATED). It may be a good intermediate solution to avoid any marker ovearheads. -- Peter Xu