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 4FE35C433EF for ; Fri, 10 Jun 2022 17:39:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347115AbiFJRjn (ORCPT ); Fri, 10 Jun 2022 13:39:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54136 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350086AbiFJRjk (ORCPT ); Fri, 10 Jun 2022 13:39:40 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3815444A16 for ; Fri, 10 Jun 2022 10:39:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1654882776; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=J8z5Zt980Qbu7w4WytKw8QIuAeP80x+ID2G+tu0x/MM=; b=ffbUZp/OCqVfiRqIWjGX0m/PjYbc7Ium/vZGuF3KAd1Z/5TYzZz25yFCjGzBN+oWqRzzPr ABtTFcMf7tKBW5sxcAuN+2q8MoeNZKSVrUe3FbrMnHIZIZsgKpQCOtlkFVVJBwPYMdG5Jm ZXYSzmhzecMJyQwwHDm9Qjvl9gQYpR8= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-614-zw12R2MDNa20VQqXLD6cww-1; Fri, 10 Jun 2022 13:39:35 -0400 X-MC-Unique: zw12R2MDNa20VQqXLD6cww-1 Received: by mail-wr1-f71.google.com with SMTP id v14-20020a5d610e000000b00213b51a0234so5713695wrt.11 for ; Fri, 10 Jun 2022 10:39:35 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:organization:in-reply-to :content-transfer-encoding; bh=J8z5Zt980Qbu7w4WytKw8QIuAeP80x+ID2G+tu0x/MM=; b=IcAnxurLGJLLR8meAd49bWW5IS+etZfxNKwoRIY05kJzgZaEkSiQKLnJjA0NeRATDv OC3TcacPN4J4LIbdt/7Yka7nkC5tzx1e3WfZFZNzchdtESXro4zG76DhDiMGTary8XVg AKZ86a+PJaQc15tROz8etq6cHyjZ3kEvnb8+ddMx9hqyjPld3tgH1wcuLdaygArB2a61 IYLd7ZH5QgucUmCj9dTrMHTOOysjmqJ35N0VExoMAD4gL0pAkf6yxJksqY3ZLsCjtu/Y V0GxwfEmjzhwZMdIfpF1OWsNc+C8fsQgX3qwclPzFkKBmJtcN6Hqsi+ZtPS1io9K6Yde Ur3A== X-Gm-Message-State: AOAM5306/XzF7lGIn6yr6oGZIlsFx+EiE3TqweqWNXXd3yIATbR1EqyB PoMfmADLR9NpJ6T2xV+bhu76BuDMGKN/bUpsE6+9LSQZQdsCc/u5DSIWnDlK7iONzXxY7HQIvr4 9C1JAllKEznVumcAp0vv1gKaaNg== X-Received: by 2002:a5d:40c7:0:b0:210:3135:e662 with SMTP id b7-20020a5d40c7000000b002103135e662mr44279391wrq.280.1654882774283; Fri, 10 Jun 2022 10:39:34 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxA4FremyZ3ut+fy1xQvwAFMxRGpPCjNehnAC2visnqTz3yALMvAKH9p08Lry8ai9np40pgtw== X-Received: by 2002:a5d:40c7:0:b0:210:3135:e662 with SMTP id b7-20020a5d40c7000000b002103135e662mr44279379wrq.280.1654882774053; Fri, 10 Jun 2022 10:39:34 -0700 (PDT) Received: from ?IPV6:2003:cb:c705:1f00:4727:6420:1d4d:ca23? (p200300cbc7051f00472764201d4dca23.dip0.t-ipconnect.de. [2003:cb:c705:1f00:4727:6420:1d4d:ca23]) by smtp.gmail.com with ESMTPSA id j20-20020adfa554000000b002100316b126sm47617wrb.6.2022.06.10.10.39.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 10 Jun 2022 10:39:33 -0700 (PDT) Message-ID: <688dccfb-ec4e-7522-b5ef-18a46337df91@redhat.com> Date: Fri, 10 Jun 2022 19:39:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: Freeing page flags Content-Language: en-US To: Mike Rapoport , Matthew Wilcox Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: From: David Hildenbrand Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 23.05.22 08:38, Mike Rapoport wrote: > On Thu, May 12, 2022 at 09:54:59PM +0100, Matthew Wilcox wrote: >> The LWN writeup [1] on merging the MGLRU reminded me that I need to send >> out a plan for removing page flags that we can do without. >> >> 4. I think I can also consolidate PG_slab and PG_reserved into a "single >> bit" (not really, but change the encoding so that effectively they only >> take a single bit). > > PG_reserved could be a PageType, AFAIR no reserved pages are ever mapped to > userspace include/linux/page-flags.h documents for PG_reserved: "Pages part of the kernel image (including vDSO)" Further, vm_normal_page() contains a comment "NOTE! We still have PageReserved() pages in the page tables. eg. VDSO mappings can cause them to exist." -- Thanks, David / dhildenb