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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 231A2EB64DD for ; Tue, 27 Jun 2023 15:57:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AEC458D0002; Tue, 27 Jun 2023 11:57:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A4D3A8D0001; Tue, 27 Jun 2023 11:57:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8ED8A8D0002; Tue, 27 Jun 2023 11:57:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 7C3EA8D0001 for ; Tue, 27 Jun 2023 11:57:31 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 419621201B3 for ; Tue, 27 Jun 2023 15:57:31 +0000 (UTC) X-FDA: 80948982702.21.D4BD871 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf19.hostedemail.com (Postfix) with ESMTP id 156B81A000A for ; Tue, 27 Jun 2023 15:57:28 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=O4LgnaJa; dmarc=none; spf=none (imf19.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1687881449; a=rsa-sha256; cv=none; b=DDzfMuKgJysOfOeLzBlzyqJ/5EJy+p6k1r1AJevEzYdzJE9Y0b9PTfbZlG/1sO2oYsY6Zh cax8vmt1mepas+NPUXo4tE8pOWwdfvQMP2Pxw0YQyR3yZFclgRzKUEn2OQl4AfKnB7YdGK 79b2ig0o0g/P0D3ohK68yCjePAfe9LQ= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=O4LgnaJa; dmarc=none; spf=none (imf19.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1687881449; h=from:from:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=grdde8Xiu7qmn+xeWQjS6jhM9eMOIEx2FTKQKHA0qcE=; b=jNr4qLDt4bL8Avj2jnP4nSyp0eB4swFS3HZYUf+4ipBkFWvLL2aL407ZG6HpPCQaak4qWF 0knjcVx3dO7gdLLhjoD6FoMp+LO2eLFDJOFnSU1D/656SEidueAnEcLRYQdeE0wz442i9p 8Cs12rxnNuj6yrWgEnWK2UZcFeOFwbQ= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=grdde8Xiu7qmn+xeWQjS6jhM9eMOIEx2FTKQKHA0qcE=; b=O4LgnaJa+96/pjOun/grMWRgf0 LntDzHo/Nz16KvqxiEr1HwXvA//H8Xwaltp+tupPUb4EjOFyVKwNxLm4bicLOTqp/7aKDRUtZ+Ti+ YkZNFYgufWM7VfJ37zBwafjppANl7Ov4YfJ/3SNrxho42WxRJ90YRkLRkEz9110OQT69JgyQix3bE 1UUN6JmWKzg8Bc5AERWCg8k1In+54bOFEIjoHmAhuJ48uTlyrsgS9ASEoWWfFX2oCx8vHeEKiHBK2 0ATl5M0lbW4dygkvrSWQNrInCol2nuI3Fn1fE8BBqWu2s6F5FIZzUwvO8Dgsb04PN8JGsMx2K7RYi V5QQ1b6Q==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qEB4A-002rlX-EZ; Tue, 27 Jun 2023 15:57:18 +0000 Date: Tue, 27 Jun 2023 16:57:18 +0100 From: Matthew Wilcox To: Hugh Dickins Cc: "Vishal Moola (Oracle)" , Andrew Morton , linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-openrisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, xen-devel@lists.xenproject.org, kvm@vger.kernel.org, Catalin Marinas , Huacai Chen , Geert Uytterhoeven , Thomas Bogendoerfer , Dinh Nguyen , Jonas Bonn , David Hildenbrand , Claudio Imbrenda , Paul Walmsley , "David S. Miller" , Richard Weinberger , Yoshinori Sato , Dave Hansen , Arnd Bergmann , Christophe Leroy Subject: Re: [PATCH v6 00/33] Split ptdesc from struct page Message-ID: References: <20230627031431.29653-1-vishal.moola@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 156B81A000A X-Stat-Signature: 5racfw35gs9nb743bnynbqhmra8gztkq X-HE-Tag: 1687881448-894692 X-HE-Meta: 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 1XRi0oO1 VsAmepCAOUBpN0QJv7xt65U+S6Mz+cWtVGqCtY9utnCpPpoI7rVImzirMzQylHag1DmLInEu29RVoOxKinefM5t7nw3OPBMJojB5PQv8t0ZG9+Vou9i9UHRzwdxF30MPSz78J95IDIJWgY/ID0lDdrhchwo+fDURlTJ42V24r9p7x4TiPtkox7o8CKjecQQjYXZexjClV3O4xj88kQdpNZsgFQQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jun 26, 2023 at 09:44:08PM -0700, Hugh Dickins wrote: > On Mon, 26 Jun 2023, Vishal Moola (Oracle) wrote: > > > The MM subsystem is trying to shrink struct page. This patchset > > introduces a memory descriptor for page table tracking - struct ptdesc. > ... > > 39 files changed, 686 insertions(+), 455 deletions(-) > > I don't see the point of this patchset: to me it is just obfuscation of > the present-day tight relationship between page table and struct page. > > Matthew already explained: > > > The intent is to get ptdescs to be dynamically allocated at some point > > in the ~2-3 years out future when we have finished the folio project ... > > So in a kindly mood, I'd say that this patchset is ahead of its time. > But I can certainly adapt to it, if everyone else sees some point to it. If you think this patchset is ahead of its time, we can certainly put it on hold. We're certainly prepared to redo it to be merged after your current patch series. I think you can see the advantage of the destination, so I don't think you're against that. Are you opposed to the sequencing of the work to get us there? I'd be happy to discuss another way to do it. For example, we could dynamically allocate ptdescs right now. We'd get the benefit of having an arbitrary amount of space in the ptdesc, although not the benefit of a smaller memmap until everything else is also dynamically allocated.