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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2BCFBC4450D for ; Wed, 21 Jan 2026 12:08:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8EF366B0005; Wed, 21 Jan 2026 07:08:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8C6746B0088; Wed, 21 Jan 2026 07:08:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7D29B6B008A; Wed, 21 Jan 2026 07:08:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 6A9AD6B0005 for ; Wed, 21 Jan 2026 07:08:09 -0500 (EST) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 14BB01A0D36 for ; Wed, 21 Jan 2026 12:08:09 +0000 (UTC) X-FDA: 84355847898.01.34DCF3E Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf17.hostedemail.com (Postfix) with ESMTP id 2B10340006 for ; Wed, 21 Jan 2026 12:08:06 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=dhakkB3L; spf=pass (imf17.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1768997287; 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=dYQuoHxFtcE3s2fOb8hPMYy2cGQnR2DrgkUSJb6gtN8=; b=qK2yCnxmo8fG9D8inRMnyJ74mgL5rAgKkD0FDoPUAfq1EOWgx+Er1vGCxM2KTFbdb0hGKo v7VYbKPU/wbpl9R7XAbF9Yz/OAtwwBZC3S9RuUpu9D6Cv7l2r6IMBfDxfP5IdiIKS5zclK /bzvAgiAnmZzruIlkEDehY/qYvLJsr8= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=dhakkB3L; spf=pass (imf17.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1768997287; a=rsa-sha256; cv=none; b=q0XPUA32ycBv8IihjdaFZgaedz1sZNBznAhPwKWMfYKECZzjxopuV58pq0mLvWWEG06/KK UnfAmMcl/G8wDLXIqOwWmCH0ZjeCd+mOSjcGnJhDOZYbF/4VMkwBpflpjs/f49mrAUGeIY cwVJYKMuWrAmCeIrThxTFfV+anAwbAM= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id C9E7040542; Wed, 21 Jan 2026 12:08:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D0AD6C19425; Wed, 21 Jan 2026 12:08:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768997285; bh=gk0BsMovNsGS2Kpyp/yON4csHC0IuD0vi07fmsUfXqo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=dhakkB3LbtxvZcMkv4y89+GP5JGm3DMVD50uq8fotcFVaBNls6RmNTZpjyWqtYqk+ D06JPppgYcJNrhvg58Yw5RKX7+3+Gh8aWBlQVzT7Y/DnghlU8UnQ08P+50KxhT3Sm9 zDafBn7ITHI0M53wc6zW4yJz0VQ4H7FqKpg9sgJ35MnH0koUxmvCPBicxM0Vjkgo1c eqJNe1D5BxKkG72OEEarDLbz62Ce0vDize0fB4x5dxEMzRAeasfpIoCrkon1aXFjGw gJha7c9bPu2aTul021JRTe+0ZSeC38/aZ2qyO1+iV1YkyHe27tVv90JLFwQ9+vXumy cED+GniKYREYg== Message-ID: Date: Wed, 21 Jan 2026 13:08:00 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/2] mm: move pte table reclaim code to memory.c To: Kiryl Shutsemau Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Qi Zheng References: <20260119220708.3438514-1-david@kernel.org> <20260119220708.3438514-2-david@kernel.org> From: "David Hildenbrand (Red Hat)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 ZW5icmFuZCA8ZGF2aWRAa2VybmVsLm9yZz7CwY0EEwEIADcWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCaKYhwAIbAwUJJlgIpAILCQQVCgkIAhYCAh4FAheAAAoJEE3eEPcA/4Naa5EP/3a1 9sgS9m7oiR0uenlj+C6kkIKlpWKRfGH/WvtFaHr/y06TKnWn6cMOZzJQ+8S39GOteyCCGADh 6ceBx1KPf6/AvMktnGETDTqZ0N9roR4/aEPSMt8kHu/GKR3gtPwzfosX2NgqXNmA7ErU4puf zica1DAmTvx44LOYjvBV24JQG99bZ5Bm2gTDjGXV15/X159CpS6Tc2e3KvYfnfRvezD+alhF XIym8OvvGMeo97BCHpX88pHVIfBg2g2JogR6f0PAJtHGYz6M/9YMxyUShJfo0Df1SOMAbU1Q Op0Ij4PlFCC64rovjH38ly0xfRZH37DZs6kP0jOj4QdExdaXcTILKJFIB3wWXWsqLbtJVgjR YhOrPokd6mDA3gAque7481KkpKM4JraOEELg8pF6eRb3KcAwPRekvf/nYVIbOVyT9lXD5mJn IZUY0LwZsFN0YhGhQJ8xronZy0A59faGBMuVnVb3oy2S0fO1y/r53IeUDTF1wCYF+fM5zo14 5L8mE1GsDJ7FNLj5eSDu/qdZIKqzfY0/l0SAUAAt5yYYejKuii4kfTyLDF/j4LyYZD1QzxLC MjQl36IEcmDTMznLf0/JvCHlxTYZsF0OjWWj1ATRMk41/Q+PX07XQlRCRcE13a8neEz3F6we 08oWh2DnC4AXKbP+kuD9ZP6+5+x1H1zEzsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCgh Cj/CA/lc/LMthqQ773gauB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseB fDXHA6m4B3mUTWo13nid0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts 6TZ+IrPOwT1hfB4WNC+X2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiu Qmt3yqrmN63V9wzaPhC+xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKB Tccu2AXJXWAE1Xjh6GOC8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvF FFyAS0Nk1q/7EChPcbRbhJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh 2YmnmLRTro6eZ/qYwWkCu8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRk F3TwgucpyPtcpmQtTkWSgDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0L LH63+BrrHasfJzxKXzqgrW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4v q7oFCPsOgwARAQABwsF8BBgBCAAmAhsMFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAmic2qsF CSZYCKEACgkQTd4Q9wD/g1oq0xAAsAnw/OmsERdtdwRfAMpC74/++2wh9RvVQ0x8xXvoGJwZ rk0Jmck1ABIM//5sWDo7eDHk1uEcc95pbP9XGU6ZgeiQeh06+0vRYILwDk8Q/y06TrTb1n4n 7FRwyskKU1UWnNW86lvWUJuGPABXjrkfL41RJttSJHF3M1C0u2BnM5VnDuPFQKzhRRktBMK4 GkWBvXlsHFhn8Ev0xvPE/G99RAg9ufNAxyq2lSzbUIwrY918KHlziBKwNyLoPn9kgHD3hRBa Yakz87WKUZd17ZnPMZiXriCWZxwPx7zs6cSAqcfcVucmdPiIlyG1K/HIk2LX63T6oO2Libzz 7/0i4+oIpvpK2X6zZ2cu0k2uNcEYm2xAb+xGmqwnPnHX/ac8lJEyzH3lh+pt2slI4VcPNnz+ vzYeBAS1S+VJc1pcJr3l7PRSQ4bv5sObZvezRdqEFB4tUIfSbDdEBCCvvEMBgoisDB8ceYxO cFAM8nBWrEmNU2vvIGJzjJ/NVYYIY0TgOc5bS9wh6jKHL2+chrfDW5neLJjY2x3snF8q7U9G EIbBfNHDlOV8SyhEjtX0DyKxQKioTYPOHcW9gdV5fhSz5tEv+ipqt4kIgWqBgzK8ePtDTqRM qZq457g1/SXSoSQi4jN+gsneqvlTJdzaEu1bJP0iv6ViVf15+qHuY5iojCz8fa0= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: 44z95kejt9adegsno81zo7juqkss3rbz X-Rspamd-Queue-Id: 2B10340006 X-Rspamd-Server: rspam05 X-HE-Tag: 1768997286-685041 X-HE-Meta: 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 MH8IvNV7 g8bTNuWeJlD6k3CXUGLe6v1irotpITtHjk//VoXlXDFnlFd97Rh0h/BPRtLR1zPhMM8QFpYgU312LcjRoM+QVk3AuOc+Bpm26YXJN7llI3bz5v3Id5LgwioaSsTHZgSB3GFfkoIzaUdxb9k9uVpw8XkgBPlwnttSdKRcDl9SgbIjPqFI5duFBT4ZYEBig7+lewOxdQ6O3OGuXByIwXfZk3khe4qopluX4dr3cwBgn6vz48fUHU9+b3kn8QMK8FqA8efwv 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 1/20/26 12:19, Kiryl Shutsemau wrote: > On Mon, Jan 19, 2026 at 11:07:07PM +0100, David Hildenbrand (Red Hat) wrote: >> The pte-table reclaim code is only called from memory.c, while zapping >> pages, and it better also stays that way in the long run. If we ever >> have to call it from other files, we should expose proper high-level >> helpers for zapping if the existing helpers are not good enough. >> >> So, let's move the code over (it's not a lot) and slightly clean it up a >> bit by: >> - Renaming the functions. >> - Dropping the "Check if it is empty PTE page" comment, which is now >> self-explaining given the function name. >> - Making zap_pte_table_if_empty() return whether zapping worked so the >> caller can free it. >> - Adding a comment in pte_table_reclaim_possible(). >> - Inlining free_pte() in the last remaining user. >> - In zap_empty_pte_table(), switch from pmdp_get_lcokless() to >> pmd_clear(), we are holding the PMD PT lock. >> >> By moving the code over, compilers can also easily figure out when >> zap_empty_pte_table() does not initialize the pmdval variable, avoiding >> false-positive warnings about the variable possibly not being >> initialized. > > mm/memory.c is a kitchen sink as it is. > > I think you miss opportunity to introduce mm/zap.c and move all zap > code. > > It can be done for code from both mm/memory.c and mm/huge_memory.c. > Line between THP and non-THP code gets more and more blurry over time. > > The same can be done for copy and fault code. I think it is going to be > more maintainable this way. While agree that memory.c contains too much stuff, I don't think zap.c is the right abstraction either. And actually, I think basic page table handling is well kept in memory.c, or moved along with other stuff (fork()) handling somewhere else. So I won't do any of that as part of this patch. -- Cheers David