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(p200300d82f40b30053f7d260aff47256.dip0.t-ipconnect.de. [2003:d8:2f40:b300:53f7:d260:aff4:7256]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a892e59659sm9856867f8f.77.2025.06.30.02.19.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Jun 2025 02:19:14 -0700 (PDT) Message-ID: <9185c50a-1427-45fc-941d-e9796cea4831@redhat.com> Date: Mon, 30 Jun 2025 11:19:13 +0200 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 v1 3/4] mm: split folio_pte_batch() into folio_pte_batch() and folio_pte_batch_ext() To: Lorenzo Stoakes Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Pedro Falcato , Rik van Riel , Harry Yoo References: <20250627115510.3273675-1-david@redhat.com> <20250627115510.3273675-4-david@redhat.com> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 27.06.25 20:48, Lorenzo Stoakes wrote: > On Fri, Jun 27, 2025 at 01:55:09PM +0200, David Hildenbrand wrote: >> Many users (including upcoming ones) don't really need the flags etc, >> and can live with a function call. >> >> So let's provide a basic, non-inlined folio_pte_batch(). > > Hm, but why non-inlined, when it invokes an inlined function? Seems odd no? We want to always generate a function that uses as little runtime checks as possible. Essentially, optimize out the "flags" as much as possible. In case of folio_pte_batch(), where we won't use any flags, any checks will be optimized out by the compiler. So we get a single, specialized, non-inlined function. > >> >> In zap_present_ptes(), where we care about performance, the compiler >> already seem to generate a call to a common inlined folio_pte_batch() >> variant, shared with fork() code. So calling the new non-inlined variant >> should not make a difference. >> >> While at it, drop the "addr" parameter that is unused. >> >> Signed-off-by: David Hildenbrand > > Other than the query above + nit on name below, this is really nice! > >> --- >> mm/internal.h | 11 ++++++++--- >> mm/madvise.c | 4 ++-- >> mm/memory.c | 6 ++---- >> mm/mempolicy.c | 3 +-- >> mm/mlock.c | 3 +-- >> mm/mremap.c | 3 +-- >> mm/rmap.c | 3 +-- >> mm/util.c | 29 +++++++++++++++++++++++++++++ >> 8 files changed, 45 insertions(+), 17 deletions(-) >> >> diff --git a/mm/internal.h b/mm/internal.h >> index ca6590c6d9eab..6000b683f68ee 100644 >> --- a/mm/internal.h >> +++ b/mm/internal.h >> @@ -218,9 +218,8 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) >> } >> >> /** >> - * folio_pte_batch - detect a PTE batch for a large folio >> + * folio_pte_batch_ext - detect a PTE batch for a large folio >> * @folio: The large folio to detect a PTE batch for. >> - * @addr: The user virtual address the first page is mapped at. >> * @ptep: Page table pointer for the first entry. >> * @pte: Page table entry for the first page. >> * @max_nr: The maximum number of table entries to consider. >> @@ -243,9 +242,12 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) >> * must be limited by the caller so scanning cannot exceed a single VMA and >> * a single page table. >> * >> + * This function will be inlined to optimize based on the input parameters; >> + * consider using folio_pte_batch() instead if applicable. >> + * >> * Return: the number of table entries in the batch. >> */ >> -static inline unsigned int folio_pte_batch(struct folio *folio, unsigned long addr, >> +static inline unsigned int folio_pte_batch_ext(struct folio *folio, >> pte_t *ptep, pte_t pte, unsigned int max_nr, fpb_t flags, >> bool *any_writable, bool *any_young, bool *any_dirty) > > Sorry this is really really annoying feedback :P but _ext() makes me think of > page_ext and ugh :)) > > Wonder if __folio_pte_batch() is better? > > This is obviously, not a big deal (TM) Obviously, I had that as part of the development, and decided against it at some point. :) Yeah, _ext() is not common in MM yet, in contrast to other subsystems. The only user is indeed page_ext. On arm we seem to have set_pte_ext(). But it's really "page_ext", that's the problematic part, not "_ext" :P No strong opinion, but I tend to dislike here "__", because often it means "internal helper you're not supposed to used", which isn't really the case here. E.g., alloc_frozen_pages() -> alloc_frozen_pages_noprof() -> __alloc_frozen_pages_noprof() -- Cheers, David / dhildenb