From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 DFBB635A386 for ; Thu, 19 Mar 2026 21:43:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773956620; cv=none; b=bzZmT7PtLHw6FmeNTIKE9ZTo6S/l8rCE2moDsEU/phBQ5T1R39HgBOOhBSje/GpLS9rBVozYkyp/C+G3Jpd3tcwWQs8kBSbEQntlyU5NYaCShYUn606n2UjjAsfglc8c18cjgtNNjOnjCxY5NL8XoOub1LciQzZbMyuwRwPnkJo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773956620; c=relaxed/simple; bh=uAw2YurztQA5Fty2B9eeqKXwLRmhsRGPv/axX4+YBZM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=o7f0OAIfmRUv9dNVKWDUKhDL/r1CLpKcJqKiI3H4sTgPUbVPqMt4850YNChNbGrO0Dgh3Lk09Z5LEbxT2GDvf5p3mwllu96gnc6TtxBWTF1wMgoDWPUOL+Jr6sjWXbudWyf/s97z7l/v4WlKpOC4SGnWy/DZwQuzirBQjv2gVwI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ET/D3WYu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ET/D3WYu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8915AC19424; Thu, 19 Mar 2026 21:43:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773956620; bh=uAw2YurztQA5Fty2B9eeqKXwLRmhsRGPv/axX4+YBZM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ET/D3WYuq275gZdLtGn6TIcVwK6gXG16ZSoxJ4xptljWXdGw9DpgJ5miOx1lqH2s/ D7jiowfnKdUOQkEKt8UVFgclc7VQoeE3crhFZe0us/f6P2rC82r4Jvsh+hwZt57WUU C0JRG109UYUaMggfN+AlBtLv5wB/VlsfInuBjT168rnNpFV4znDNNlXjpQi6AICbVI Yn3Vfyx2FXraKVaIRwDw4yIaMaoYqF7ijhcnYsvuuqjYhthIx8Yj+FJ9uFxBOEZYYr 29v3bzAvD95qPs+PYMuoNG85Oywcfz64n/nWo5HwMlDzevyih8XkiERKtMHQZptehU HQTDKZhlGusOg== Message-ID: <7cd1e50a-f5a1-42b6-9d04-4e329d338f41@kernel.org> Date: Thu, 19 Mar 2026 22:43:35 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/4] mm/mprotect: special-case small folios when applying write permissions To: Pedro Falcato , Andrew Morton , "Liam R. Howlett" , Lorenzo Stoakes Cc: Vlastimil Babka , Jann Horn , Dev Jain , Luke Yang , jhladky@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260319183108.1105090-1-pfalcato@suse.de> <20260319183108.1105090-5-pfalcato@suse.de> 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: <20260319183108.1105090-5-pfalcato@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/19/26 19:31, Pedro Falcato wrote: > The common order-0 case is important enough to want its own branch, and > avoids the hairy, large loop logic that the CPU does not seem to handle > particularly well. > > Signed-off-by: Pedro Falcato > --- > mm/mprotect.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/mm/mprotect.c b/mm/mprotect.c > index aa845f5bf14d..23a741f9a4c8 100644 > --- a/mm/mprotect.c > +++ b/mm/mprotect.c > @@ -170,6 +170,13 @@ static __always_inline void commit_anon_folio_batch(struct vm_area_struct *vma, > int sub_batch_idx = 0; > int len; > > + /* Optimize for the common order-0 case. */ > + if (likely(nr_ptes == 1)) { > + prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, 1, > + 0, PageAnonExclusive(first_page), tlb); > + return; > + } > + > while (nr_ptes) { > expected_anon_exclusive = PageAnonExclusive(first_page + sub_batch_idx); > len = page_anon_exclusive_sub_batch(sub_batch_idx, nr_ptes, That should likely be squashed into patch #1, because only then the inline makes more sense. -- Cheers, David