From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793622197; b=4plPDudy+5TI0kwYbmHGPJ9+LAlfwX7keHQHDc2SgSdUa0SZRqp6pPfFhqOncKkYQR9o mbYS8Ooj4J1YEEOvgzeAHfWWoUXgk+TfvHlZd2fdloaiAFQpU8Oo6sQL3HrjoLLNd3Hgm zCiM44O40zR9vHRxHkpcOjZjrk0g0OtkQ6L93KuNpbf+jk6Zy2c5VRJFeMETo+uWAbait YygtnaYXzrh1HE9Qqq1PaK5JrHxwbIgyuTEaEPtNzRRLpZoJ9g9M3fj2rrMuu86KjydZ0 F0v+bAnAGacgiN7jlyF6eUKMg7FLZ9qMrG2DM4DIsv7S/hQ/6rvd5CHVTZ8ecQkLc3w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793622197; h=Received:DKIM-Signature:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:Content-Language:Autocrypt:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=li9rdtwFeFEI907CKymYxoxqt6E52soBIe74zDvChPY=; b=SdkwFoU6wXs1qHeJ0eg0nDexpFfEQV3EbLpeDD8JYYSOkbeauPjjWCqLPTOyK9CqovKS hQxgl3j3W67ExnBeju7VWDrq5H1yvAhJUgi5Y4VGoM98qqzcEbXuVneoegv4TzqMBjW57 5I/lyJ7aK6bDAvCCgxuntt6tBpi2NGLtu1vhLZjTJKDqAqdm9i/nAw5HVLRE4rBwmeQNS R+mN3ePMpkriLEYHwH+VXcNUNOdDcy+8R+lTWBPFocQYvz2J2Zw/fPWV4P0wF22NpjlTL JlDLxQ1qu5C2EB7E1tuQURO1/r2J8v45YhrPBIofSnKxzwwcM8Rz7bwZ6zrE/nVQfZA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Sn38Pua9; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D582760A383E for ; Mon, 2 Nov 2026 12:23:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Sn38Pua9 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 935861F00A17; Mon, 2 Nov 2026 12:23:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793622196; bh=li9rdtwFeFEI907CKymYxoxqt6E52soBIe74zDvChPY=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Sn38Pua9rV7W527YONSvg8EOeoe21NRVadTNMAE+Z3XemtkQsub6vqQfGdkX01x5M MOIhConomswlo1fkXRSOUOFOfSJtqXMvUJqkkGONdlJYve5aowRZzUSPIOzrbYEsTu 4rcTL7z2MlBCiHcTLQZFKzKfgB7ISwjtD2TU4IIuUFoLKp6g/B4EeCB2nVJe45jaqB NwcHMAJa2uhvTM2lExWSoiiPkCXLGYNOtsblsQk4zNxZGJiJ9MKwWeiCjRq+aa4MQQ HLywUOptpCxfwl+Sdaba7b2X9BZoWMDpB9gi67UarljvvraX2804Hg/Jsozuojt8BO 7xuWawvf1CuoQ== Message-ID: Date: Mon, 2 Nov 2026 13:23:11 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/4] mm: internal: introduce FPB_LOCKLESS for folio_pte_batch_flags() To: Yeoreum Yun , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Jason Gunthorpe , John Hubbard , Peter Xu , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Andrew Morton , Rik van Riel , Yuan-Hao Hsu References: <20261102-refactor_gup_fast-v2-0-bc1ac018c834@arm.com> <20261102-refactor_gup_fast-v2-3-bc1ac018c834@arm.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: <20261102-refactor_gup_fast-v2-3-bc1ac018c834@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/2/26 12:30, Yeoreum Yun wrote: > From: Yuan-Hao Hsu > > Add support for calling folio_pte_batch_flags() in GUP-fast context when we are > not holding the PT lock. Instead of reading PTEs through ptep_get(), we have to > use ptep_get_lockless(). > > Specify the new behavior through a new flag FPB_LOCKLESS. We'll make use of this > functionality for batching PTEs in gup_fast_pte_range() next. > > Signed-off-by: Yuan-Hao Hsu > Signed-off-by: Yeoreum Yun > --- > mm/internal.h | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/mm/internal.h b/mm/internal.h > index b4d0df4c35adf..c1824b0193f4d 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -373,6 +373,12 @@ typedef int __bitwise fpb_t; > */ > #define FPB_MERGE_YOUNG_DIRTY ((__force fpb_t)BIT(4)) > > +/* > + * Read the page table entries with ptep_get_lockless(): the caller does not > + * hold the page table lock (e.g, GUP-fast). > + */ > +#define FPB_LOCKLESS ((__force fpb_t)BIT(5)) > + > static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) > { > if (!(flags & FPB_RESPECT_DIRTY)) > @@ -442,7 +448,7 @@ static inline unsigned int folio_pte_batch_flags(struct folio *folio, > ptep = ptep + nr; > > while (nr < max_nr) { > - pte = ptep_get(ptep); > + pte = (flags & FPB_LOCKLESS) ? ptep_get_lockless(ptep) : ptep_get(ptep); > > if (!pte_same(__pte_batch_clear_ignored(pte, flags), expected_pte)) > break; > Acked-by: David Hildenbrand (Arm) -- Cheers, David