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 5CFC4CD4F35 for ; Wed, 13 May 2026 10:03:39 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 99BB16B0005; Wed, 13 May 2026 06:03:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 923CD6B008A; Wed, 13 May 2026 06:03:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7C4896B008C; Wed, 13 May 2026 06:03:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 66F196B0005 for ; Wed, 13 May 2026 06:03:38 -0400 (EDT) Received: from smtpin06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay02.hostedemail.com (Postfix) with ESMTP id F19D51207B5 for ; Wed, 13 May 2026 10:03:37 +0000 (UTC) X-FDA: 84761959674.06.DE1219F Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf16.hostedemail.com (Postfix) with ESMTP id EE0E618000F for ; Wed, 13 May 2026 10:03:35 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=QYQeNyMT; spf=pass (imf16.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=1778666616; 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=FA+d0KPwbeDJDyO8jDcrFphrE/mc/PVRZRNuSXXA3/w=; b=jarynVu/+5wVt0gk3idfVuzcLH2/Y2vMTjHYzscJoFDgVMKJnt2SXT5FLYeE8ouP8NdVkL In7yOGS8srzwr548SOjhGi0jk0jQAm0ayyLXqQNvT7Z16F19sDbeuvx6TyWQsuBfRNm//n MLq7IXeca6O7eUAyfMX7uODEaYi7e7o= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1778666616; a=rsa-sha256; cv=none; b=sw5M1Y6YqRg40lEMQDdXjs06/Pwy/jZQrRbD/WlJsUo0AVPUFW5vhyulfPEpCXbE0jHT0u YUZHh+vaPROaEC5paxvUcOEwVG79u4hYCmKyHrJ+fRnny5w/R1BlCyeo/B4ZLIPVk8GPNm nZRe08adk42A/nAMzBFVyc4Ze+vA2pU= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=QYQeNyMT; spf=pass (imf16.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 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 05597444FB; Wed, 13 May 2026 10:03:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6F18C2BCB7; Wed, 13 May 2026 10:03:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778666614; bh=uNr/uFHa8lFJk/JJ/8kd9ZumVdyGQuQQfbYHdUl02UA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=QYQeNyMThpHjuSLKa58f6dppmWVqBeBwSraMrvGJW3jNALwIswOENNrssr9p9eTBR Q3aMvEfZFP+wFNDCbqCVIID/PyxalTbdPQy/d4sWJJkNODltdx2dFIbqTgYHOVCSoB o+x01VAEcKRnWfVOq896D4oaoy82xi+n3/bEaUkrzst0INftTsXsRAbZiIOeyhKflz lQnQVp928t+BO9kjs9ISzqh2vYZ6O2GILsrYPSDEY8qXCcVUiFVRWEABkx3wFA5bqt Gmlh0fwZTTPBaae/HTBvWClE4tJyF27OeL2ZLc8nZbQ5TX6bjVBl/M+txt/WCt4NBV rFKP3SPG1FF5Q== Message-ID: <65596f86-e6a3-48b0-aa3d-2e608964e29d@kernel.org> Date: Wed, 13 May 2026 12:03:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] mm/shmem: add shmem_insert_folio() To: =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , =?UTF-8?Q?Christian_K=C3=B6nig?= , intel-xe@lists.freedesktop.org Cc: Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Hugh Dickins , Baolin Wang , Brendan Jackman , Johannes Weiner , Zi Yan , Huang Rui , Matthew Auld , Matthew Brost , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260512110339.6244-1-thomas.hellstrom@linux.intel.com> <20260512110339.6244-2-thomas.hellstrom@linux.intel.com> <26479389-459b-4cc4-914d-e7d29d5e5cc9@kernel.org> <1ce447ceea88bbe56c7d28654a51fc2856a7f986.camel@linux.intel.com> 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: <1ce447ceea88bbe56c7d28654a51fc2856a7f986.camel@linux.intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: EE0E618000F X-Rspam-User: X-Stat-Signature: 9p4ozw9xm5pxfndfhxfapxtndotp5cas X-HE-Tag: 1778666615-151600 X-HE-Meta: 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 HpR3pZnX iV6I8oWYQmLF8C3kFz1Paj9rjjXvQTfTYh0SwdEP6mEXlJw5FjI1egwEXGJNajffP+BsleVXaex3OROZlAsDQgPfudFn2Ef/k6hfpv+uSymgHN5UTmljByNrZYaywI2+zZRQczqmv1e+MqDXmaEE9tI0EcrpsVIy4WCULBsqP6egYc3iZPC5hM/g+b+sijfwplHYXZYq7ovtInHMxs2T/lKMy3nYJBliEgUaKFtYYyXtzbYd1QInLp1Itd4azN85pMmFp2zRikFRgJIwWPaLg7QfuoK5HaxqQhirf3Do4lMt2BC+WC28TCHpGJsdLtxodQVWUXhY/SiBa8oE= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/13/26 10:51, Thomas Hellström wrote: > On Wed, 2026-05-13 at 10:37 +0200, David Hildenbrand (Arm) wrote: >> On 5/13/26 09:47, Christian König wrote: >>> Hi David & Thomas, >>> >>> ... >>> >>> Exactly that is one of the major reasons why we aren't using a >>> shmem as backing store for TTM buffers in the first place. >> >> What was the problem with that the last time this was considered? >> >> shmem nowadays supports THP (e.g., 2M) and even mTHP (e.g., 64K). >> >> For internal mounts, it must be enabled accordingly >> (/sys/kernel/mm/transparent_hugepage/.../shmem_enabled). >> >> Some distributions still default to "never". I guess if an admin >> enables it, you >> would just get THPs. > > FWIW, the i915 driver which uses shmem "natively" uses a special mount > here that gives back THPs. > >> >> If "distro default" is the only problem, I guess we could think about >> how to >> improve that. For example, just let internal GPU DRM objects allocate >> any folio >> size available and supported etc. >> >> Would that make it possible to just use shmem natively? (e.g., how >> would this >> interact with shmem features like folio migration, would that be >> workable with >> DRM objects?). > > Currently the drivers that use shmem in this way use > "mapping_set_unevictable()" as long as the object is bound to the GPU. > Then shrinkers can unbind from GPU and revert that setting. Right, but mapping_set_unevictable() only affects folio_evictable() - -reclaim behavior. Not other properties (such as folio migration). > > The problem, (as also stated in the cover letter of this series) is for > drivers that need to change caching of the pages to WC or UC. I assume you mean "To be able to easily maintain pools of pages mapped uncached or write-combined". Can you point me at the code that changes the caching of the pages? > That's an > extremely costly operation so TTM needs to pool such allocations. > That's where using shmem natively becomes very ugly, because you can't > really use a 1:1 mapping between shmem objects and DRM objects anymore. So you would require different caching attributes within a DRM object? -- Cheers, David