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 58F7EC9831E for ; Thu, 24 Sep 2026 20:31:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 722446B0088; Thu, 24 Sep 2026 16:31:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6D3276B0096; Thu, 24 Sep 2026 16:31:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5C1966B0098; Thu, 24 Sep 2026 16:31:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 387F66B0088 for ; Thu, 24 Sep 2026 16:31:01 -0400 (EDT) Received: from smtpin09.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id D51781A04A2 for ; Thu, 24 Sep 2026 20:31:00 +0000 (UTC) X-FDA: 85249799880.09.B6608DF Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf21.hostedemail.com (Postfix) with ESMTP id 17D291C0008 for ; Thu, 24 Sep 2026 20:30:58 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=dwzxLk1z; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf21.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1790281859; 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=7QesB3wn8+yidQJfEr/89OKxUr18TgMww+mIYXxRsD0=; b=hS6TwB2Q94FM44pPwvvLlIHdvfAy1JGRJ7iaKCFNHdNANsu+yR5FFSqLVk+uLhuj+APVz2 fGns4SDB+8Fc1ecGaKn1KpaxQV+lH5MbWAtPIFtPGBZ4Haq3Wviy5SPdK4578HojWQKlp1 lmAlKNi+Fh8dpCp5pFvo7D2JYYwEUQ0= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=dwzxLk1z; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf21.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1790281859; b=d0PBZOMxvWbBHAj8+G3faDMZHyeTBbsnSpDbbN3EtVYbTVLflO14HPSyrc9pvgbfwAwif+ xmYcq8gHh64dCB4+xkNMv03mKCRwbe63W6s4Az1rudoLn1ijqktQt2LtfyOIkT7lBT9YqB l/WxwdHDE2BEenFCzpNYjR6o5X9nb+I= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 869D860230; Thu, 24 Sep 2026 20:30:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 952081F00893; Thu, 24 Sep 2026 20:30:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790281858; bh=7QesB3wn8+yidQJfEr/89OKxUr18TgMww+mIYXxRsD0=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=dwzxLk1zFjuelEjbXSV1QpGBOpalmXXXwREbsm4ynBL02XEnvhS+KtKgYliWpRGdq xBQBouEEARo9WI4lxyUPxdSIRjVbsoh1q5EAZ9CBIKQhDe+Mby8nwQ5C2Eu/ce0aoc N+JA+6L+tfIdMTfLyYzFQ7q1e/Ps2Ep6SBrGQnibpWm2SOA6kXu4Y4soAANgI80KXo NJkETdjZz+7xtcfrV2SlITh2YXd6ikHSVLj12W51FQdPpBw2NAe2OdRyOGp45+S0V9 QB66EBYVDUQ7hHgPuC5DX76C5hjnZkNIVbZeCevhtJo4smCmvP2ySX/ueDGXTw+bod x/L7WQo+UxuOw== Message-ID: <4842e76f-c30b-4204-922c-ecdd02d627dc@kernel.org> Date: Thu, 24 Sep 2026 22:30:47 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RESEND v7 13/29] mm: zswap: reject high-order swap cache allocations backed by zswap To: Usama Arif , Andrew Morton , chrisl@kernel.org, kasong@tencent.com, ljs@kernel.org, ziy@nvidia.com, linux-mm@kvack.org Cc: ying.huang@linux.alibaba.com, Baoquan He , willy@infradead.org, youngjun.park@lge.com, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, alex@ghiti.fr, kas@kernel.org, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, Nico Pache , "Liam R. Howlett" , ryan.roberts@arm.com, Vlastimil Babka , lance.yang@linux.dev, linux-kernel@vger.kernel.org, nphamcs@gmail.com, shikemeng@huaweicloud.com, yosry@kernel.org, qi.zheng@linux.dev, luizcap@redhat.com, kernel-team@meta.com References: <20260914122950.3283997-1-usama.arif@linux.dev> <20260914122950.3283997-14-usama.arif@linux.dev> 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: <20260914122950.3283997-14-usama.arif@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: b1donxbzpt8no7q8ytu6xgnpd8zjrsq6 X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 17D291C0008 X-HE-Tag: 1790281858-513662 X-HE-Meta: U2FsdGVkX18Dmr1cUsFOMYm4WZm2yDOfYIdW3E49xBle1y13As6xcg6hRPiluvr3US7BBXsDCIXAurAbyOCBnEkR0FZGz2fVHhSQD1Lv0KXtBX6XACUcvMHVT5cX5WKT4bvJ0rYZGxRz3Nk508bqp9JTahX6uSzg8Rvihu2MzCpzJBvJ9nkrYnHCzeQcnGq2ryQvKPegBh+M8oszXU68qMpxUwrevt6Dsvg9xzqBxDt2VKuighZJfJdSbeLIn2Hww2Hm+AS3rWIE5ocfJHD151RpYEfYTg4G0HFKERF3iKAsunEsdo7lbst1JXaETHMsUuDDcKGv8RQbLAylyYhj0daGpvx+Xnj/kUb/JDlXc5G+2uljqdzUbkLEOIO7Xoc/QUECUCeHuaw337HWiimdBP/j+UQ4KV04/mfy2B+lplh1jfLMDT66xBf7cdu/2tfl9hdFVz9DcolMESN4VzhCexT1ll9VOruV/ez8Ud1A09gsOxAJq98YXlyqo8KraSgUoO3s2ETdad3NAX9c49bdmW85I2oNsCZvSMo/UtWUhGBrbExFLbl3EL0myQ96Df1g5BomfSipivn61LJJr1DMuZjdvZSOjftQYeRsaPO0JJO38HIs5+HehXM2TGX8GMFxbdoR1jHDUu+W38QMz+UMnSeeT50aedCbb2iDUOpupSemBzzTDW9kKnkd6nl42iQnV8W5vFGC2d6PKURvLfEHTd8FpfcRxPpp8++9FfAy5AxUV3tuQxSREjujH0mrZfKePCpqjmRnEoY2h5LNzYmeVG6MyfoOwswlaToLWqHElPEFTBIbkoz9apO9ychYRFY5/sfRdJwtY+S5r5md340hnVGkiwe3DmhwmtkXQNGlVz6Kud9hX4SsmO/5hkCJ3+IdNAEsAcagpxcA1CNqRWpL7vam/EGlUv4dgXtbbAeMAYE629tANgxivG+PTY+mmSYjl1HLoYxm0hcTPDDiXK5 wqMHMTAX x4ojakjkNIuLNLLmxx3IV52FjZ//ylsYFgNyILblTT8ezbpjRQHJbzvgRTrmtXzK7URnxcev/21lffkmfeVkT7RlqDS0lKouU4ypYcFBioILJ0VppQqs53nGJni5epEKj3fm96xFZKH4DXh7QzZlG2rAm1PG32HrD31JJJB69PZ6AICNO+ZPRAVsc/PLWfzOywiLSmqdnhMU04FR2yeMVudUZ7UYW0Mgz5Gca34JO7ut/vFVJDX4wDb2WxoHuk9hp0QUF Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/14/26 14:28, Usama Arif wrote: > zswap stores swapped-out pages one at a time, so a range of swap slots can > be split between zswap entries and the backing device. A high-order > swap-cache folio over such a range cannot be read back in one go: the disk > read would return stale or zero data for every slot zswap owns. > > Reject that in __swap_cache_alloc(). Do the check after the folio is in the > swap cache: from that point zswap can neither start storing nor start > writing back any slot in the range, so the answer is stable. Callers > already fall back to order-0, which zswap_load() handles per page. > > Export zswap_is_present() for the PMD-order swap-in users added later. > > Co-developed-by: Alexandre Ghiti > Signed-off-by: Alexandre Ghiti > Signed-off-by: Usama Arif > --- For 10:30pm that is way over my head to review. I'll rest assured that zswap folks have that under control. -- Cheers, David