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 9BEDE3B6BEB for ; Thu, 19 Mar 2026 21:28:52 +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=1773955732; cv=none; b=HaFm//H4zF3y4Uaul2R9uELKXuuokOFynOPsKPLmGIzzLysJqJxz6fJAm5yTtYKEzOtQDutcWJz/sz6c59wwin9QEaeSjAhJcgikR7b/UPogyEDU5CIGATdzVSNJJk4cxaOOgbzX6PXG7K7UsLZ46bc9KqdmsPWxOGhMTXmaAyk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773955732; c=relaxed/simple; bh=/A2pi1IEpX2B/0J45JYoubtua2rh5RakAG442Dsy7Pc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=S1YuGdVe7zLzQ2qbcYvPBvKBafzp/zHgNql70V2CzSfATuFIrHUpLIAwUQA8bTn4asDQIn018aj+pwT6xn9E7Z+HVR5GsbRQNiY43EMf+nFKkBl0TWi1o96n2CrftRm+CvCcD1idPoTfGJORFLFdspAfqXlYt7CNn5RYNQxji9o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iIWABuTI; 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="iIWABuTI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58338C19424; Thu, 19 Mar 2026 21:28:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773955732; bh=/A2pi1IEpX2B/0J45JYoubtua2rh5RakAG442Dsy7Pc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=iIWABuTI3Iy9u45wopTGhujY252zv9MxOCTJde9C4J1yO7CwLK4U1uTJh+pS3eNFl 9cC0sVwQoSggVrLNV+IbLVxdgRJf1phdj+Y/DQr46eUAGP4Y9+7BglECOz0PIR6T9e VGqY4kJZoUQVws+gVPcdm7Z8IFy7P/g7VcGZ4KGYEARAYj9UBmSJTLPvOWcAsIiFpm JcOZ0BrBfEa2WzKPRu12MxJe+0T7p+tJdlSbia9Rx2HbfdyIHDouLNaXjSAEFjZCdB y6n/upUwFG1Y8fJ7Z9n/cgiwx3qKnaeNuy3EK9NFmAwZdxg68XtiJY3U8S3l9FAWzX zSYaAtF8RGNIg== Message-ID: <9943a6ad-9c85-439c-ad9e-39a694a29147@kernel.org> Date: Thu, 19 Mar 2026 22:28:47 +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 1/4] mm/mprotect: encourage inlining with __always_inline 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> <20260319183108.1105090-2-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: <20260319183108.1105090-2-pfalcato@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/19/26 19:31, Pedro Falcato wrote: > Encourage the compiler to inline batch PTE logic and resolve constant > branches by adding __always_inline strategically. > > Signed-off-by: Pedro Falcato > --- > mm/mprotect.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/mm/mprotect.c b/mm/mprotect.c > index 9681f055b9fc..1bd0d4aa07c2 100644 > --- a/mm/mprotect.c > +++ b/mm/mprotect.c > @@ -103,7 +103,7 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, > return can_change_shared_pte_writable(vma, pte); > } > > -static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep, > +static __always_inline int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep, > pte_t pte, int max_nr_ptes, fpb_t flags) > { > /* No underlying folio, so cannot batch */ > @@ -117,9 +117,9 @@ static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep, > } > > /* Set nr_ptes number of ptes, starting from idx */ > -static void prot_commit_flush_ptes(struct vm_area_struct *vma, unsigned long addr, > - pte_t *ptep, pte_t oldpte, pte_t ptent, int nr_ptes, > - int idx, bool set_write, struct mmu_gather *tlb) > +static __always_inline void prot_commit_flush_ptes(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep, pte_t oldpte, pte_t ptent, > + int nr_ptes, int idx, bool set_write, struct mmu_gather *tlb) > { > /* > * Advance the position in the batch by idx; note that if idx > 0, > @@ -169,7 +169,7 @@ static int page_anon_exclusive_sub_batch(int start_idx, int max_len, > * pte of the batch. Therefore, we must individually check all pages and > * retrieve sub-batches. > */ > -static void commit_anon_folio_batch(struct vm_area_struct *vma, > +static __always_inline void commit_anon_folio_batch(struct vm_area_struct *vma, > struct folio *folio, struct page *first_page, unsigned long addr, pte_t *ptep, > pte_t oldpte, pte_t ptent, int nr_ptes, struct mmu_gather *tlb) > { >From my micro-optimization work on zapping and fork, I learned that these batching functions are best optimized for order-0 page by explicitly calling them from the code with "nr_ptes == 1" and then force-inlining them. nr_ptes and all loops will essentially be optimized out. With no such explicit constants, is there really a real benefit to be had here? -- Cheers, David