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[2003:cb:c715:8600:f05d:97b6:fb98:2bc1]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3675a0cd66fsm18988535f8f.8.2024.07.04.08.41.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 04 Jul 2024 08:41:40 -0700 (PDT) Message-ID: Date: Thu, 4 Jul 2024 17:41:39 +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 05/45] mm/pagewalk: Enable walk_pmd_range to handle cont-pmds To: Oscar Salvador , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Peter Xu , Muchun Song , SeongJae Park , Miaohe Lin , Michal Hocko , Matthew Wilcox , Christophe Leroy References: <20240704043132.28501-1-osalvador@suse.de> <20240704043132.28501-6-osalvador@suse.de> Content-Language: en-US From: David Hildenbrand 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: <20240704043132.28501-6-osalvador@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 04.07.24 06:30, Oscar Salvador wrote: > HugeTLB pages can be cont-pmd mapped, so teach walk_pmd_range to > handle those. > This will save us some cycles as we do it in one-shot instead of > calling in multiple times. > > Signed-off-by: Oscar Salvador > --- > include/linux/pgtable.h | 12 ++++++++++++ > mm/pagewalk.c | 12 +++++++++--- > 2 files changed, 21 insertions(+), 3 deletions(-) > > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h > index 2a6a3cccfc36..3a7b8751747e 100644 > --- a/include/linux/pgtable.h > +++ b/include/linux/pgtable.h > @@ -1914,6 +1914,18 @@ typedef unsigned int pgtbl_mod_mask; > #define __pte_leaf_size(x,y) pte_leaf_size(y) > #endif > > +#ifndef pmd_cont > +#define pmd_cont(x) false > +#endif > + > +#ifndef CONT_PMD_SIZE > +#define CONT_PMD_SIZE 0 > +#endif > + > +#ifndef CONT_PMDS > +#define CONT_PMDS 0 > +#endif > + > /* > * We always define pmd_pfn for all archs as it's used in lots of generic > * code. Now it happens too for pud_pfn (and can happen for larger > diff --git a/mm/pagewalk.c b/mm/pagewalk.c > index d93e77411482..a9c36f9e9820 100644 > --- a/mm/pagewalk.c > +++ b/mm/pagewalk.c > @@ -81,11 +81,18 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, > const struct mm_walk_ops *ops = walk->ops; > int err = 0; > int depth = real_depth(3); > + int cont_pmds; > > pmd = pmd_offset(pud, addr); > do { > again: > - next = pmd_addr_end(addr, end); > + if (pmd_cont(*pmd)) { > + cont_pmds = CONT_PMDS; > + next = pmd_cont_addr_end(addr, end); > + } else { > + cont_pmds = 1; > + next = pmd_addr_end(addr, end); > + } > if (pmd_none(*pmd)) { > if (ops->pte_hole) > err = ops->pte_hole(addr, next, depth, walk); > @@ -126,8 +133,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, > > if (walk->action == ACTION_AGAIN) > goto again; > - > - } while (pmd++, addr = next, addr != end); > + } while (pmd += cont_pmds, addr = next, addr != end); Similar to my other comment regarding PTE batching, this is very specific to architectures that support cont-pmds. Yes, right now we only have that on architectures that support cont-pmd-sized hugetlb, but Willy is interested in us supporting+mapping folios > PMD_SIZE, whereby we'd want to batch even without arch-specific cont-pmd bits. Similar to the other (pte) case, having a way to generically patch folios will me more beneficial. Note that cont-pmd/cont-pte is only relevant for present entries (-> mapping folios). -- Cheers, David / dhildenb