From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0A41B3B71B6; Tue, 11 Aug 2026 12:11:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786450311; cv=none; b=qkf5rDq2L25ojW3JgZWbA7/eHDFNBuWyAXTUAjc5ECYnz5W89jBNCrMIN3Ub/Epn6QIsTBXkGTt2lKRgJD8xEzyPK7YNSYuP+7xuZN2CZ18bNi3z/jVn8XE7fncleGkw11E3BKH+GwJVIU+20TW7BJ9czFDWeHNGI60kVq6O23Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786450311; c=relaxed/simple; bh=nInDi7/nGPIcNHx3XhP2r2B28pAKpq9pB70NVwqzbGE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Gk32dfASBvrkSV3p/hImwynhbRzUr+HtWIXajxl1Ugawg3zjfRxOtkXgtyftpsFm1YpKug7I2Yav/RIeIAXkppO5Mvlv2SuAWWPyqoQC1ydgfiRE6/HOx5+hpW1LMK2rS/14o6xZNA5bnL5hTJm/v4xMD5Ec4xRzMsHk7a0/WOY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oMzFJcn9; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="oMzFJcn9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E88261F000E9; Tue, 11 Aug 2026 12:11:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786450309; bh=/fTG1Cghw/RG7+KE3x88oxH8TI74VawrjBf3qjRRniY=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=oMzFJcn9VOzkFaKMEx9vCYCdx1Pq7igNm3SDyOEjzrOpDudIApIUK8tbQWGyhMTA2 t05Mkqhok9RLYIMUol0cpCiu3QthaSWyzaAoYQ2iTd1AckujJZDZf2+JmOHRJ0KvP7 mcsYLS8a7sO8YaLXbyWEeOK99DFlaVD5L55J3MTekojG6h3FMWYgpjeoMH//X24lZs 5lfWAxjxOdrK+/s8jDuKs0rLQeM8RFflAxNY1JPwZF3i/yhkf94kLkVqbTR4mmJWjo hK2SQwlx7kI/9C/spjKPKM5IkvDG9SLQ6RAQ5o7kkbgcPTchuBQb5gh+4ZPvUgW8mp IkyibBYe3lp/w== Message-ID: Date: Tue, 11 Aug 2026 14:11:31 +0200 Precedence: bulk X-Mailing-List: linux-parisc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 6/9] mm: convert PTE table entry to pte To: Muhammad Usama Anjum , Alexander Gordeev Cc: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Simona Vetter , Dimitri Sivanich , Arnd Bergmann , Greg Kroah-Hartman , "James E.J. Bottomley" , Helge Deller , Juergen Gross , Stefano Stabellini , Muchun Song , Oscar Salvador , Andrew Morton , "Liam R. Howlett" , Lorenzo Stoakes , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Peter Zijlstra , Andrey Ryabinin , Pasha Tatashin , Chris Li , Kairui Song , Uladzislau Rezki , Steven Rostedt , Masami Hiramatsu , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , SJ Park , "Matthew Wilcox (Oracle)" , Jan Kara , Jason Gunthorpe , Leon Romanovsky , Miaohe Lin , Dennis Zhou , Tejun Heo , Christoph Lameter , Mike Rapoport , Johannes Weiner , ziy@nvidia.com, pfalcato@suse.de, ryan.roberts@arm.com, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-parisc@vger.kernel.org, xen-devel@lists.xenproject.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, kasan-dev@googlegroups.com, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, damon@lists.linux.dev References: <20260806083926.1807279-1-usama.anjum@arm.com> <20260806083926.1807279-7-usama.anjum@arm.com> <5c329236-7761-4e42-a549-b822e43b4358@arm.com> <2599c5b3-e8ac-4865-993b-d41e6f060d52-agordeev@linux.ibm.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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/10/26 13:06, Muhammad Usama Anjum wrote: > On 10/08/2026 7:44 am, Alexander Gordeev wrote: >> On Fri, Aug 07, 2026 at 05:26:04PM +0100, Muhammad Usama Anjum wrote: >>> Yes, this is particular line is for non MMU. In this case, CONIFG_ARCH_HAS_HW_PTE >>> would never be defined. Hence hw_pte_t is just pte_t and direct dereference is >>> allowed. I'd thought a lot about it; is better to leave direct dereference here >>> or use some helper. Then used __pte_from_hw() was already being used in generic >>> ptep_get(). >> >> But in case CONIFG_ARCH_HAS_HW_PTE=n __pte_from_hw() is still gets called. >> That looks inconsistent to me. Why not just call ptep_deref() (see below)? > > Agreed. Calling __pte_from_hw() directly exposes the representation > conversion at the call site. I will introduce ptep_deref() and use it > here. > >> >>> There are only two users of __pte_from_hw() at this time. >>> >>> ptep_get_sw() or ptep_get_deref() is better name here? >> >> ptep_deref() would be it. >> >> Do you agree to the suggested API requirements? > > Yes. hw_pte_t * identifies storage containing hardware-formatted PTEs, > regardless of whether it is attached. ptep_get() is used for attached > entries and may provide additional architecture-specific handling. > ptep_deref() is used for unattached entries and performs only the raw > storage-to-value conversion. > > For review, this patch would become: > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index bc0b9c65aa1d0..ce900d2652d91 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -1283,7 +1283,7 @@ static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, > #ifdef CONFIG_MMU > return ptep_get(ptep); > #else > - return *ptep; > + return ptep_deref(ptep); > #endif > } > > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h > index 1768421755a9c..08613593f3320 100644 > --- a/include/linux/pgtable.h > +++ b/include/linux/pgtable.h > @@ -490,6 +490,13 @@ static inline int pudp_set_access_flags(struct vm_area_struct *vma, > #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ > #endif > > +#ifndef ptep_deref > +static inline pte_t ptep_deref(hw_pte_t *ptep) > +{ > + return __pte_from_hw(*ptep); > +} > +#endif > + > #ifndef ptep_get > static inline pte_t ptep_get(hw_pte_t *ptep) > { > I mean, how many such users do we expect? 1? :) Why have a helper for that then, that seems to encourage it's use, when really people should be using ptep_get() ? -- Cheers, David