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 BC7BFC3DA59 for ; Mon, 22 Jul 2024 13:29:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 550BB6B007B; Mon, 22 Jul 2024 09:29:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4D9506B0083; Mon, 22 Jul 2024 09:29:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 304D16B0085; Mon, 22 Jul 2024 09:29:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 0D6F36B007B for ; Mon, 22 Jul 2024 09:29:53 -0400 (EDT) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 718D4A181B for ; Mon, 22 Jul 2024 13:29:52 +0000 (UTC) X-FDA: 82367471424.26.1CB29F9 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf16.hostedemail.com (Postfix) with ESMTP id 19AA5180020 for ; Mon, 22 Jul 2024 13:29:49 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=fLCwrejS; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf16.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1721654956; a=rsa-sha256; cv=none; b=gXeraGyM4X2qXus7I7XDpuRfn22T+pGiosgARYr+HCxh/4YKW3kRMa5lBVBg9/VOOX4QGM p2EkC8ScEd3wFle4KNcH8rmwxvo3xV1QS5kgTZg/VaIYZRDzoayXPMvKE6m6LXefX3VLlQ bmTDb5iOZb0an+KZ7cFpYlkvIXSoIXo= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=fLCwrejS; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf16.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1721654956; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=hj0518Q+ag2Y9NZVcsCpncBBpD7wr8EEpXH9Btxb4Io=; b=3RD1Qj411Jgwk1KlPzug1wmwg32R2QMAHesfXmXqvUDIly1LNu52C9LaTtqS4RRPKH2DBV F7UyX6pHZrR3ec9P7AlTcTUDGWOTndxEyOkbu9TdX6HIaCers1Wd7kYRY/39ER+59Q27qt MW6cfB2YlKUCAKnM4rytbwGIaPm4+ag= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1721654989; 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:autocrypt:autocrypt; bh=hj0518Q+ag2Y9NZVcsCpncBBpD7wr8EEpXH9Btxb4Io=; b=fLCwrejSGd8EwhkzncuiF35/KqnR0ZoEGsXcooJjWf5WqReaxZInyvko+EUbWp84GIF20a BJKDv073G8lciS/AQBNKxLjcg/Ywc683jBcXpyBuAFr+sq0NzWXMSh3yHtUZkCpPVMPjBg 8MxlZGuAokjukKCMmd+zT6bFevsNbDM= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-651-9JMvYhheOMWQ0prJl0ZBbA-1; Mon, 22 Jul 2024 09:29:46 -0400 X-MC-Unique: 9JMvYhheOMWQ0prJl0ZBbA-1 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-42667cc80e8so32766565e9.2 for ; Mon, 22 Jul 2024 06:29:46 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1721654985; x=1722259785; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=hj0518Q+ag2Y9NZVcsCpncBBpD7wr8EEpXH9Btxb4Io=; b=nF8cTXFb46RtVdfx0mzRBGk++yvAZW/0K17LN19uvFFj3tFLPEc9LxFw8jeRLR63VY 2otRn3hi/ktzF8OhwiTSfmoxRnsL7+u5Eheu7WyyCmHvXo5ak+MS7TP+hTjOcAneJpXT orDcs9PxntC7Icl+C3FtvJ/ZCx7dC70BkCa0L3MtNz+DSuL3MJJ/0m+7Ey9UfNLK0TLp lE4XcuLDMmEgkeDWLfU2iG7ZFuTXzuPkp2TFtx+WlLSsjkwtFUjnrhukmpXZlZa2aAwN k2QtT7M5rTmTL511wAlOk3wS+8U/WRhV7zRfMehVYlhiEKx8pfpEcKYXSS4w4Vqzpcxz Hsdw== X-Forwarded-Encrypted: i=1; AJvYcCXLzqbd1ZlyXkVMvl4zvb4jw6AOHghPfkkTFoFJlgpa8gHIl0rqykBmqjxsBhP5Yb3vihCmGXPrcxZFHjzKZ4TdriI= X-Gm-Message-State: AOJu0YyjFePSH/og3MexUESbfsWkO3Fpv1Wr2FdQI85Ad/vxzZyXRKH/ fhbMtopyRJWNRMwLG+Cc1NQzLEiw+hz9TOfiXhmTiH5EE2Jf91tH9Kgv9+9SqCs2FUkY578rHEl 8biyc3be9hvyRDaRpSbJFTqI0JsTGTZufSR3Ss9KsrrMTpmlV X-Received: by 2002:a05:600c:a4c:b0:426:6389:94c4 with SMTP id 5b1f17b1804b1-427ea1d5a2dmr9070815e9.37.1721654985318; Mon, 22 Jul 2024 06:29:45 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGIyw9dA2YYXh0wR+3Pj025bxjyvTGi6gFSINBbowgn9GBPFQbhi8MNgjqnWB9eXV6rnCmpfg== X-Received: by 2002:a05:600c:a4c:b0:426:6389:94c4 with SMTP id 5b1f17b1804b1-427ea1d5a2dmr9070715e9.37.1721654984893; Mon, 22 Jul 2024 06:29:44 -0700 (PDT) Received: from ?IPV6:2003:cb:c727:7000:c050:e303:f8a7:6ed9? (p200300cbc7277000c050e303f8a76ed9.dip0.t-ipconnect.de. [2003:cb:c727:7000:c050:e303:f8a7:6ed9]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-427d6900caasm126895385e9.11.2024.07.22.06.29.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 22 Jul 2024 06:29:44 -0700 (PDT) Message-ID: Date: Mon, 22 Jul 2024 15:29:43 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 0/6] mm: THP-agnostic refactor on huge mappings To: Peter Xu , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Vlastimil Babka , Oscar Salvador , linux-s390@vger.kernel.org, Andrew Morton , Matthew Wilcox , Dan Williams , Michal Hocko , linux-riscv@lists.infradead.org, sparclinux@vger.kernel.org, Alex Williamson , Jason Gunthorpe , x86@kernel.org, Alistair Popple , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, Ryan Roberts , Hugh Dickins , Axel Rasmussen References: <20240717220219.3743374-1-peterx@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20240717220219.3743374-1-peterx@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 19AA5180020 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: ez9hja1dtsrwwwq8tqkjn3g18m813z7w X-HE-Tag: 1721654989-843289 X-HE-Meta: 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 aLxbcFN3 LKlu5a0xdfrN8WhnD2MClp8IXa+pe4Kxjr08sQiS18buK3DOu/oBqaFxyFttbNV1mo2NplGUayAPrsiBOx3lLGjo4O/QW8DjZ9lrhQKB8MNfuWz0JT0bAerCBSHa3gWfyIajVnIOKiIydXLx58uWS+vWRFBOFHyAsWNUuP983gPJOzzBn//1kx8gBJOfzHntQW966RryrKAl4njSsGSbhL9vkgfX+1layrUB277lRpMs7ePaYc5FL6xgWdj+j+5orI5xgXp1rQ4FhGVs1Lam5Fi8dmKn3ptAvjpw5jSTlQXuUvGiP5LsIWc9ckOmkq45kCOxV97f8O56665mCLsTDgt1vxPE5EQ7+WuYUBbob5YXYt/bok0icC3m93NpXpi0QcK02OckSa5MPXo1YiFriJQeZFnBmic64fXCOrrIHQjgupgetBIIH6BOzBOnwGBq9+qXwSuJor7Q6PhY= 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: List-Subscribe: List-Unsubscribe: On 18.07.24 00:02, Peter Xu wrote: > This is an RFC series, so not yet for merging. Please don't be scared by > the code changes: most of them are code movements only. > > This series is based on the dax mprotect fix series here (while that one is > based on mm-unstable): > > [PATCH v3 0/8] mm/mprotect: Fix dax puds > https://lore.kernel.org/r/20240715192142.3241557-1-peterx@redhat.com > > Overview > ======== > > This series doesn't provide any feature change. The only goal of this > series is to start decoupling two ideas: "THP" and "huge mapping". We > already started with having PGTABLE_HAS_HUGE_LEAVES config option, and this > one extends that idea into the code. > > The issue is that we have so many functions that only compile with > CONFIG_THP=on, even though they're about huge mappings, and huge mapping is > a pretty common concept, which can apply to many things besides THPs > nowadays. The major THP file is mm/huge_memory.c as of now. > > The first example of such huge mapping users will be hugetlb. We lived > until now with no problem simply because Linux almost duplicated all the > logics there in the "THP" files into hugetlb APIs. If we want to get rid > of hugetlb specific APIs and paths, this _might_ be the first thing we want > to do, because we want to be able to e.g., zapping a hugetlb pmd entry even > if !CONFIG_THP. > > Then consider other things like dax / pfnmaps. Dax can depend on THP, then > it'll naturally be able to use pmd/pud helpers, that's okay. However is it > a must? Do we also want to have every new pmd/pud mappings in the future > to depend on THP (like PFNMAP)? My answer is no, but I'm open to opinions. > > If anyone agrees with me that "huge mapping" (aka, PMD/PUD mappings that > are larger than PAGE_SIZE) is a more generic concept than THP, then I think > at some point we need to move the generic code out of THP code into a > common code base. > > This is what this series does as a start. Hi Peter! From a quick glimpse, patch #1-#4 do make sense independent of patch #5. I am not so sure about all of the code movement in patch #5. If large folios are the future, then likely huge_memory.c should simply be the home for all that logic. Maybe the goal should better be to compile huge_memory.c not only for THP, but also for other use cases that require that logic, and fence off all THP specific stuff using #ifdef? Not sure, though. But a lot of this code movements/churn might be avoidable. -- Cheers, David / dhildenb