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 E6D20C5B572 for ; Thu, 13 Aug 2026 07:13:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B8EC76B01AA; Thu, 13 Aug 2026 03:13:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B679A6B01AB; Thu, 13 Aug 2026 03:13:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A7CA76B01AE; Thu, 13 Aug 2026 03:13:13 -0400 (EDT) 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 804B16B01AA for ; Thu, 13 Aug 2026 03:13:13 -0400 (EDT) Received: from smtpin02.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 7D472A2C10 for ; Thu, 13 Aug 2026 07:13:11 +0000 (UTC) X-FDA: 85095379782.02.D5400CD Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf02.hostedemail.com (Postfix) with ESMTP id A22688000C for ; Thu, 13 Aug 2026 07:13:09 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=YaH3wzyy; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf02.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1786605189; 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=ljZR619xg+IXw5LIW+/SpuAVOzKILECXTZKiydlMDrw=; b=34/YKphlbiT6qvYwc2VJBAV00rKnpBwuZ6IaB5dAK2qLlD+bk01JyQii+VIMHx8EoJ8POs LEnORe5OYydRdJdo0cZ8I+rVJ+SDHRamtopTRQT7KseLTBIZX6YPOEqFdG5JyA3MrCVXCi GfJIzK+fn9EK0CzhQKUcMRt5YXaebuc= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=YaH3wzyy; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf02.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1786605189; b=0eH6CjR0/nR3Pzp2QB0GLUbvShe1XA6NKBrL7C6megfwotxz/YSteiYMYl54CfqejoMzyL lr2TtmO6qfrhRPgENGN8lVGT8ffwrcMifSAbOuAcvlCV0GulR/qWGWhyl4QV5A08lKbUT+ o6DOwvJEWxscpYCIE1WXFVm7MZ4VOJc= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 9CB644037B; Thu, 13 Aug 2026 07:13:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D21551F000E9; Thu, 13 Aug 2026 07:13:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786605188; bh=ljZR619xg+IXw5LIW+/SpuAVOzKILECXTZKiydlMDrw=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=YaH3wzyygs1VGyF3sOYA2UaFAQ3B0Vla5iInKG9FE3ZDZPkQvi3cyQmQNeXFR1XHc dhPW7kRsGOKKOGz+Xd3UChuCft253Iw7vXf6s4VvED7WhgGiXZQBo6wdPJxNDSxhmZ UVAvuHO2YzanXeSk4psp7bhqgOAeHB0DeCnjl51ucWJk/Kp35u2ByRJpBk60aKkDgv 6Zsxe+bohU3dUeu87O9rX8DEgxaZ+eY2vENmhbuaHbvp1aLhS4Ln1lja8SjO86Ug0W JoIU8Wr7C00avKW17GoYKml/WW/CK3iw86U13XpOclb5nzQldXBZ7fLwYbR5COdfh2 qVx1QxoXDGd4w== Message-ID: <6bfa6c93-4eb5-46c6-9524-7b59297f3601@kernel.org> Date: Thu, 13 Aug 2026 09:13:02 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 5/7] mm/khugepaged: Refactor the PTE state checks into a helper To: Zi Yan , "Nico Pache (Red Hat)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Cc: Andrew Morton , Lorenzo Stoakes , Baolin Wang , "Liam R. Howlett" , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Shuah Khan References: <20260811-khugepaged_pte_refactor-v4-0-ddac39d61c4a@linux.dev> <20260811-khugepaged_pte_refactor-v4-5-ddac39d61c4a@linux.dev> <753cb38f-66b4-4bd0-8b53-7480efe30ec3@kernel.org> From: "David Hildenbrand (Arm)" 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: xzwjcoj4z4f448ekpd47gwk8wuiu8a57 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A22688000C X-HE-Tag: 1786605189-944305 X-HE-Meta: U2FsdGVkX19I9f5RpeWA4tyPcGsencgXA1/oMEce7Aw9Z5ZHXWYlO1ijhQqkts9N889bMQG6q/8XL7LPkkuBwW3jFy7a3OkmEBq7vWNdlpS3ENpcLYvZ9/69UHOJji0pB2WbJOEw8c6GJfVVNFKR/RAGqF9kTSv2BFcBy5iV1WmU6Qm1nk/mObk5wph2QaAS/BnRRJrUre2Q/oVVP9jR7jv7RImsqVJgmjHJkVEKUplRIm8DvSMeZIv8pgIIs5Op3O81dbwIsH728htXVr3bjsomnzwrRFIICvbHbYu9g7H+GjxEYMR5dkRahJho/69gH1EihtGmXzbM23MomjzZsde+diHyC0c9Jb5bP6DIHZ7Z+UGAeirwHfflMRhWrXaup6Hvveivyy6Mz8IM3Hryq2hFaImwRItq94dVundVcYX+TdUQuxY38dQdK+It7j8SMCV/yLHuOEhmsyZ4tgd82JE1QQVE6i+pcm53Fieqv9fGkCgGYRGJsH1tu7RpXWpqQhp1mGA/MjsmQkFdfRAAbjDgaFwu1/zIigfg/zJ43lWKxnNZuKRIjHwG02z1nZh9GC1EDBMauK6mjQRwICIyxocujIxiyAJ0w0BFSgYtlcwxfmdriNllF9hdjESURNuZ0g5C7zUJ84KSn7iUjcSoutjdX7PpNlmPtN8WsgMEKEWfoprDvZ8u0oFFvPGM8Jwcprdqnw/O5MVDbAJKb1M45czk37IyHa2Lsj6rC1H3KTraOeaRuTInlfGGvSkc2wJPU/As7d31KtE3+5ILw9zja101vnbJqZMFDXXx7hjlC+Gm2KNRoqNV7Jw8xSL7kCxj+LYYp2qDjk+qYt8pIfujam4U2Kq4XfY+jLFy/Hi2WD3nq8g2D9jbaHYoJts3apFgtxl57pS81Oq6v+Qi9YAIFR5bInzQ+l7zbxXBu3QTrAnQ2ICrygCfx6CpRjm1F9gjhCFolbnxSB+zTWmAIFQ XnYSFTk0 qqAf6t+Z4aN38+X7DB4XEF/nFhNpZwmosnPypHAefthTSFNE8KJylKZMFZra4XTt4XofTF7M2eFC2Hk6BfuRjD2Vu5rRMF3qa4vR57STLGIH+V76l/EtO48QlZinYdwzErL2xKNTufjDMJA59thDgKTgHz7GEvXLEYprnV66aUuxAYHJ3sqqZr6oiUHbfUNV7nWq8dtKIleQd/GVDyGtffwM2qXZRV+xmLd3/6AH7MLbkfzKTX+nVs5uz9ePVMVvWPQ4U Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: >> + if (!pte_present(pteval)) { >> + if (ctx->max_ptes_swap < 0) >> + return SCAN_PTE_NON_PRESENT; >> + if (++ctx->nonpresent_ptes > ctx->max_ptes_swap) { > > So max_ptes_swap is actually max_ptes_nonpresent. But due to > khugepaged's max_ptes_swap config name, we just keep the variable and > related function names that way? Yes, that's how we handle it today, unfortunately, for historical reasons. Mistakes were made. I think we might be able to convert this code to actually only count swap entries, and simply reject any other ones (migration, hwpoison, ...), but that's something for another patch. [...] > > SCAN_SUCCEED + folio != NULL means to proceed with the pte, while > SCAN_SUCCEED + folio == NULL means to skip the pte. > > collapse_anon_pte_check() probably needs to document this? Not really, as you say it's straight forward if you look at it from what's actually happening: SCAN_SUCCEED + folio != NULL: check folio SCAN_SUCCEED + folio == NULL: don't check folio (no folio to check?) -- Cheers, David