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(p200300d82f3c3a00566226b33e5d438e.dip0.t-ipconnect.de. [2003:d8:2f3c:3a00:5662:26b3:3e5d:438e]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-443000ee99csm133714505e9.31.2025.05.19.09.42.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 May 2025 09:42:40 -0700 (PDT) Message-ID: Date: Mon, 19 May 2025 18:42:39 +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 v4 1/4] mm/page_isolation: make page isolation a standalone bit. To: Zi Yan Cc: Oscar Salvador , Johannes Weiner , linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , Baolin Wang , "Kirill A . Shutemov" , Mel Gorman , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Richard Chang , linux-kernel@vger.kernel.org References: <20250509200111.3372279-1-ziy@nvidia.com> <20250509200111.3372279-2-ziy@nvidia.com> <506798aa-0280-4f63-9c0e-d5f2f5d58c3c@redhat.com> <166E73A3-02CE-4023-AE0E-022C9C618C33@nvidia.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: <166E73A3-02CE-4023-AE0E-022C9C618C33@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit >>> +#ifdef CONFIG_MEMORY_ISOLATION >>> + if (flags & PB_migrate_isolate_bit) >>> + return MIGRATE_ISOLATE; >>> +#endif >> >> If you call get_pfnblock_flags_mask() with MIGRATETYPE_MASK, how could you ever get PB_migrate_isolate_bit? > > MIGRATETYPE_MASK is ((BIT(PB_migratetype_bits) - 1) | PB_migrate_isolate_bit), > so it gets PB_migrate_isolate_bit. > Oh ... that's confusing. >> >> >> I think what we should do is >> >> 1) Rename get_pfnblock_flags_mask() to get_pfnblock_flags() >> >> 2) Remove the mask parameter >> >> 3) Perform the masking in all callers. > > get_pfnblock_flags_mask() is also used by get_pageblock_skip() to > get PB_migrate_skip. I do not think we want to include PB_migrate_skip > in the mask to confuse readers. The masking will be handled in the caller. So get_pageblock_skip() would essentially do a return get_pfnblock_flags() & PB_migrate_skip_bit; etc. > >> >> >> >> Maybe, we should convert set_pfnblock_flags_mask() to >> >> void set_clear_pfnblock_flags(struct page *page, unsigned long >> set_flags, unsigned long clear_flags); >> >> And better, splitting it up (or providing helpers) >> >> set_pfnblock_flags(struct page *page, unsigned long flags); >> clear_pfnblock_flags(struct page *page, unsigned long flags); >> >> >> This implies some more code cleanups first that make the code easier to extend. >> > > The same due to PB_migrate_skip. > > Based on your suggestion, we could make {set,get}_pfnblock_flags_mask() > internal APIs by prepending "__". They are only used by the new > {get, set, clear}_pfnblock_flags() and {get, set, clear}_pageblock_{skip, isolate}(). > Then use {get, set, clear}_pfnblock_flags() for all migratetype operations. > > WDYT? In general, lgtm. I just hope we can avoid the "_mask" part and just handle it in these functions directly? > >>> + return flags; >>> } >>> /** >>> @@ -402,8 +423,14 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, >>> unsigned long bitidx, word_bitidx; >>> unsigned long word; >>> +#ifdef CONFIG_MEMORY_ISOLATION >>> + BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 8); >>> + /* extra one for MIGRATE_ISOLATE */ >>> + BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits) + 1); >>> +#else >>> BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4); >>> BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits)); >>> +#endif >>> bitmap = get_pageblock_bitmap(page, pfn); >>> bitidx = pfn_to_bitidx(page, pfn); >>> @@ -426,6 +453,13 @@ void set_pageblock_migratetype(struct page *page, int migratetype) >>> migratetype < MIGRATE_PCPTYPES)) >>> migratetype = MIGRATE_UNMOVABLE; >>> +#ifdef CONFIG_MEMORY_ISOLATION >>> + if (migratetype == MIGRATE_ISOLATE) { >>> + set_pfnblock_flags_mask(page, PB_migrate_isolate_bit, >>> + page_to_pfn(page), PB_migrate_isolate_bit); >>> + return; >>> + } >>> +#endif >>> set_pfnblock_flags_mask(page, (unsigned long)migratetype, >>> page_to_pfn(page), MIGRATETYPE_MASK); >>> } >>> diff --git a/mm/page_isolation.c b/mm/page_isolation.c >>> index b2fc5266e3d2..751e21f6d85e 100644 >>> --- a/mm/page_isolation.c >>> +++ b/mm/page_isolation.c >>> @@ -15,6 +15,17 @@ >>> #define CREATE_TRACE_POINTS >>> #include >>> +static inline bool __maybe_unused get_pageblock_isolate(struct page *page) >>> +{ >>> + return get_pfnblock_flags_mask(page, page_to_pfn(page), >>> + PB_migrate_isolate_bit); >>> +} >>> +static inline void clear_pageblock_isolate(struct page *page) >>> +{ >>> + set_pfnblock_flags_mask(page, 0, page_to_pfn(page), >>> + PB_migrate_isolate_bit); >>> +} >> >> Should these reside in include/linux/pageblock-flags.h, just like the >> CONFIG_COMPACTION "skip" variants? > > They are only used inside mm/page_isolation.c, so I would leave them > here until other users come out. get_pageblock_skip() and friends are also only used in mm/compaction.c. Having these simple wrapper as inline functions in the same header should make it consistent. ... and avoid tricks like "__maybe_unused" here :) -- Cheers, David / dhildenb