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 49EA9CD4851 for ; Tue, 12 May 2026 06:25:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 823996B0093; Tue, 12 May 2026 02:25:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7D4316B0096; Tue, 12 May 2026 02:25:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6C3696B009D; Tue, 12 May 2026 02:25:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 59EB26B0093 for ; Tue, 12 May 2026 02:25:41 -0400 (EDT) Received: from smtpin13.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 20F70140389 for ; Tue, 12 May 2026 06:25:41 +0000 (UTC) X-FDA: 84757781682.13.4C4BC80 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf18.hostedemail.com (Postfix) with ESMTP id 72D931C000B for ; Tue, 12 May 2026 06:25:39 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=KPJcQ42l; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1778567139; a=rsa-sha256; cv=none; b=29UNyODxrng5Uq+yDK+i5axbrqV9jPxIOYSBx4VopIljhJhbOn7PadCHelm6OIkzR+CN97 yM7sfjy2gmQQx6lA5vFIY/UDcKFIDtyRLNDfIUJJbQj/eq4Nlf3rhMP1zokbZNgvvHtnlu Yc4GeKiii50z/46pnVNfTjLaRluph+o= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=KPJcQ42l; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf18.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=1778567139; 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=f1acAZ/Sh8ScpKdVt9NyUqWQyZ/FLoN5Ha7ECc0GdNA=; b=sHt+invU1BCY1KjDD6kpDkbPehlPY8FGpLtlOyedRS/WaPhQY6pL1u0uX2bIggybwiP1OP kV855bAgnDuTK9pR1DycIJTeDCRgF2hg3WM56Z5U5Q6JBD51iGOPIPANiHCSktKvjbtxvV CB/GULCP3NkuGYLt2vDTJkQMAfs7jEA= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id C55D060123; Tue, 12 May 2026 06:25:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 390C1C2BCF7; Tue, 12 May 2026 06:25:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778567138; bh=bvbc8NXu/FH7JnxQJ63NcUmUspxbFGn5COPiYbadr3A=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=KPJcQ42lqoBcaETRv9s+IzNGz//Ivc3JXk62CLGniVddCcT7ZanylFrpu5HvNcC72 8YEE0SbmT1B3xZ4lA1+2Qsjkh1eXEslJ/tY8CMEED1WfQJQ14v9wTsLocbwC9h3gCL jccrj5ez6EJPBy2q3LVN/R1TErMfH+SvCgv2cpqkH611/p+ILQTxG6cVhb0ucvazyI F90DLpobyL8sA1ptsK1UAA3yb7vOWSkrGWgpanWP2o/5xSobicfFs8pvRks7wYEXMK 5dQVpp0DW6QfrHV0VstIURYs3Hxu6a8pKNDYl/Wc2Wo+kLpw1dZZjii2Jp2ju/Itia HTqfliANKU/Zg== Message-ID: <9171623c-4775-49e9-bc05-3ecf1a81c7bb@kernel.org> Date: Tue, 12 May 2026 08:25:31 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drivers/base/memory: make memory block get/put explicit To: Muchun Song Cc: Muchun Song , Oscar Salvador , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , linux-mm@kvack.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org References: <2841f424-580c-48c6-bb26-de30e4397b7f@kernel.org> <3234B4D3-8202-4E79-B85B-8B6373BB76F6@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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: hbm9wepjo1xyaz5mx5edmg7w7i1gxcjb X-Rspam-User: X-Rspamd-Queue-Id: 72D931C000B X-Rspamd-Server: rspam07 X-HE-Tag: 1778567139-783680 X-HE-Meta: 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 iKX4kIOd lL0mUZjM6EYuERHZ53rNzQWyiBGL9iyJN6R/wzFdCeKZiSFFaHQfamGTbIwO0OD2AORp/0llby6/noQtfqF60cnwahmEOlaSVO2Rsq87JQLo6eeN73fmDHXB/RJCblzeRh9vPlFDvT/4+oA5b7rORlSwgs8MXviGbaQRIEJ8rWhxYmJORYEVWCuz9DAyRlTi4UQBL6b/6q+MNmi0655AQh0m347w9DN5s/K/HZrO60UPzaadZ2x3H80d80vgStG4PZCw2Z778s4GyFmA8uyyhBBidXFul7wqdbjNf Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/12/26 05:11, Muchun Song wrote: > > >> On May 11, 2026, at 21:23, Muchun Song wrote: >> >> >> >>> >>> On 5/11/26 13:18, Muchun Song wrote: >>> >>> Better mention some of the other changes here, like removing find_memory_block(). >> >> Will do. >> >>> >>> [...] >>> >>> >>> While at it, please drop the "extern". >> >> OK. >> >>> >>> >>> Would guards come in handy here? >> >> You mean to introduce something like: >> >> scoped_guard(memory_block, id) { >> } >> >> Right? If yes, I will give it a try. > > Hi David, Hi, > > Did I get that right? I assume so, but it's indeed rather ugly. ... in particular the CLASS and scoped_class() thingies are pretty intuitive. I thought we could use guard()/scoped_guard(), but reading the details, it's mostly for locks only. There is only one users of scoped_class in the tree (overlayfs). Maybe, if we would do this properly, we would actually provide our own wrappers, like MEMORY_BLOCK scoped_memory_block not even providing "memory_block_get", as that would be implicit. Like MEMORY_BLOCK(mem)(block_id); // the second () is confusing scoped_memory_block(mem, block_id) { } But that requires more thought, and I don't really know what the best practice is there ... So thanks for trying, but let's leave it as is for now. -- Cheers, David