From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 44CA93E123E; Fri, 5 Jun 2026 10:56:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780656997; cv=none; b=KKGO0/m0I1IcVPCBbaPgcoSHz7eUa4mxyNz8g6/21JjOdnPyBgnrUFbtVC3YU9C1ayNJC+IN4Chw5lC96uP86SZXDe7mnibv46l7ZB+a3LwrH+rbx+csenlRSrJv44I1P/xF2l9lTRaGQv2P0Ccbc8t8v5PfyWZxp9yddMWH7rw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780656997; c=relaxed/simple; bh=qrBjB8lzTK112ZuUEtbeZFSWvGmRim+4+Tv42fPij7w=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=enUoTHQ+aUnG8C2F2rSJSmLiFMLR/iRsdanjgLfA7WK+svf0R1IWg7ZzD8glu2uIu+Clwa3nI4sa7+xF7lNSPL1vs1lvOv9xoKkapUE/RTX+8YdqFyyDBBT6LM/ksUy3t04emAY9h7Op+qae6jmMM4dOTHRlOXXt4Lx33/GoxQY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Q23J5p0k; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Q23J5p0k" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5716D1F00893; Fri, 5 Jun 2026 10:56:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780656995; bh=GUm8w415k6U8QcFmjz5s7cPq1GIEQMx0uHtMtXak1VU=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Q23J5p0kWQAPg+EEk4Q+GJHKXIm0nGZ8UXg2IGF2TUJGaXUt3cT0i97qo9ACbrUt1 /im3EqNL3g8t1nKW31dJ0xDZz7Os0VVS5nfzXNFxbaYJIVqfabg0Y2ZavdhQDtaIla OmhVjByX1bBOlxUxG6FSBZAyLQnQA1aG3xRQG9TJjibsg5FYF13UXTcKXcOBKRXilw bLzo7CpUorzdHchml9B1caftDJjOhtVI2oeocxWqfsYTfiYjYEI4uzp6HovO8OZDGB gOCLAZJiQ4PJRiYc6R0wy694Pr4xwht/VA8wxUY5e03IWG745MmM/i1G2l179F1MMx eDq8zmBgS9olg== Message-ID: <3752203b-9806-42aa-83be-8b88dec12e21@kernel.org> Date: Fri, 5 Jun 2026 12:56:20 +0200 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/15] mm: introduce ANON_VMA_LAZY for deferred anon_vma creation To: Lorenzo Stoakes Cc: xu.xin16@zte.com.cn, tao.wangtao@honor.com, catalin.marinas@arm.com, will@kernel.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, akpm@linux-foundation.org, willy@infradead.org, sj@kernel.org, kees@kernel.org, luizcap@redhat.com, zhangjiao2@cmss.chinamobile.com, kas@kernel.org, hpa@zytor.com, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, jack@suse.cz, riel@surriel.com, harry@kernel.org, jannh@google.com, jgg@ziepe.ca, jhubbard@nvidia.com, peterx@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, chengming.zhou@linux.dev, nao.horiguchi@gmail.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, pfalcato@suse.de, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, damon@lists.linux.dev, shakeel.butt@linux.dev, ryncsn@gmail.com, dvander@google.com, wangzicheng@honor.com References: <20260604111035154Lk-9ZgwKY4Nlk4zz30U1t@zte.com.cn> <68a4aec0-72d4-4967-b063-b57cc7ee40cf@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 6/5/26 12:07, Lorenzo Stoakes wrote: > On Fri, Jun 05, 2026 at 11:38:52AM +0200, David Hildenbrand (Arm) wrote: >> On 6/4/26 05:10, xu.xin16@zte.com.cn wrote: >>> >>> Indeed, it's very complex, but having the changes of 15 patches scattered across >>> various subsystems is really frustrating for reviewers. It took me a whole day to >>> read through the entire patch set, which made an already complicated matter even >>> more complex (maintaining such complex code in the future will be a pain). >>> >>> However, overall, I think the original intention behind Tao's patch is innovative >>> and valuable, and Tao could definitely make this patch set simpler and more >>> readable, because the core changes actually start from PATCH 10. >>> >>> I believe that if Tao had done the following, things might have gone better and easier >>> for reviewing. In fact, I understand the motivation behind the patch is quite simple >>> at its core (just wanting to avoid allocating the anon_vma structure when a VMA hasn't >>> been truly forked, and instead put the VMA information directly into folio->mapping): >>> >>> 1) You could actually simplify your patch significantly — without adding a lot of wrappers >>> and helper functions that introduce extra review overhead — and keep only the most essential elements. >>> >>> 2) Provide complete test code (in tools/testing/selftest) that covers the affected functionality, >>> such as VMA, huge pages, KSM, etc. >>> >>> 3) Use the RFC tag to start a discussion. >>> >>> >>> I would be very glad to see if Tao could post a simpler v2 version that does not alter the rmap >>> core data structures too much and does not introduce excessive complexity, no matter whether >>> it can be merged finaly. >> >> I'm afraid, the overall complexity would increase in any case. >> >> So to quote myself "But fundamentally, I think we want to find a new design that >> is just naturally simpler." > > In general I'm prioritising my work, and hope to ship something within the next > month, even if it might just be some early bits of work on this to plumb stuff > in, and certainly the main ting will be an RFC :) Cool, I'll cover your back on upstream review as much as you need :) -- Cheers, David