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[2003:cb:c71c:4e00:b097:7075:f6ba:300a]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-36d27156c95sm4397595f8f.22.2024.08.09.00.22.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 09 Aug 2024 00:22:39 -0700 (PDT) Message-ID: <62d758b1-595a-4c05-ab89-3fe43d79f1bf@redhat.com> Date: Fri, 9 Aug 2024 09:22:38 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 1/2] mm: collect the number of anon large folios To: Barry Song <21cnbao@gmail.com> Cc: akpm@linux-foundation.org, baolin.wang@linux.alibaba.com, chrisl@kernel.org, hanchuanhua@oppo.com, ioworker0@gmail.com, kaleshsingh@google.com, kasong@tencent.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ryan.roberts@arm.com, v-songbaohua@oppo.com, ziy@nvidia.com References: <41b49313-5804-46ba-9e1d-358b079274cd@redhat.com> <20240809070412.33847-1-21cnbao@gmail.com> 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: <20240809070412.33847-1-21cnbao@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: B0D58140012 X-Stat-Signature: 9k6dowpqfzzgwiaffaujixshe45p7537 X-Rspam-User: X-HE-Tag: 1723188163-809126 X-HE-Meta: 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 vU1jAyOf vBu7MW0aVNzehx+XRxa1XnkgJA2qKSFmjW1A0Krs0zkXmS/trSxJwrXCufS+9fVJqSp/ww/3Q1vAJb/epqILB+/6h2G84LIsa6rvxXYSqvpmLe/KfLRQxqrBmZBDR85clcRTgWe0iCFd6yKAt20mf8ZqxipHw8X1B1XOeDGLgDbR7rp++sG1FTJOCLlrTazQ3abNtWrDt381XhlVvqS3cvR8/NOXUUZ9siLkhAtKp3z3NpQ/XyErr039FCVy/qi/Kb7r8r7H0/KAgzWfoQTrr9rLlTGBh1MCMN7ErAGYu3guuHkwgVulMDTAxHnGLGCogyQ2WInK2pzTB0wl8jO3ux3LNt8LoIt70LFWhGs+iw4KVWU0gjq7SJHbJdw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 09.08.24 09:04, Barry Song wrote: >>>> I would appreciate if we leave the rmap out here. >>>> >>>> Can't we handle that when actually freeing the folio? folio_test_anon() >>>> is sticky until freed. >>> >>> To be clearer: we increment the counter when we set a folio anon, which >>> should indeed only happen in folio_add_new_anon_rmap(). We'll have to >>> ignore hugetlb here where we do it in hugetlb_add_new_anon_rmap(). >>> >>> Then, when we free an anon folio we decrement the counter. (hugetlb >>> should clear the anon flag when an anon folio gets freed back to its >>> allocator -- likely that is already done). >>> >> >> Sorry that I am talking to myself: I'm wondering if we also have to >> adjust the counter when splitting a large folio to multiple >> smaller-but-still-large folios. > > Hi David, > > The conceptual code is shown below. Does this make more > sense to you? we have a line "mod_mthp_stat(new_order, > MTHP_STAT_NR_ANON, 1 << (order - new_order));" > > @@ -3270,8 +3272,9 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, > struct deferred_split *ds_queue = get_deferred_split_queue(folio); > /* reset xarray order to new order after split */ > XA_STATE_ORDER(xas, &folio->mapping->i_pages, folio->index, new_order); > - struct anon_vma *anon_vma = NULL; > + bool is_anon = folio_test_anon(folio); > struct address_space *mapping = NULL; > + struct anon_vma *anon_vma = NULL; > int order = folio_order(folio); > int extra_pins, ret; > pgoff_t end; > @@ -3283,7 +3286,7 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, > if (new_order >= folio_order(folio)) > return -EINVAL; > > - if (folio_test_anon(folio)) { > + if (is_anon) { > /* order-1 is not supported for anonymous THP. */ > if (new_order == 1) { > VM_WARN_ONCE(1, "Cannot split to order-1 folio"); > @@ -3323,7 +3326,7 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, > if (folio_test_writeback(folio)) > return -EBUSY; > > - if (folio_test_anon(folio)) { > + if (is_anon) { > /* > * The caller does not necessarily hold an mmap_lock that would > * prevent the anon_vma disappearing so we first we take a > @@ -3437,6 +3440,10 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, > } > } > > + if (is_anon) { > + mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); > + mod_mthp_stat(new_order, MTHP_STAT_NR_ANON, 1 << (order - new_order)); > + } > __split_huge_page(page, list, end, new_order); > ret = 0; > } else { > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 408ef3d25cf5..c869d0601614 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1039,6 +1039,7 @@ __always_inline bool free_pages_prepare(struct page *page, > bool skip_kasan_poison = should_skip_kasan_poison(page); > bool init = want_init_on_free(); > bool compound = PageCompound(page); > + bool anon = PageAnon(page); > > VM_BUG_ON_PAGE(PageTail(page), page); > > @@ -1130,6 +1131,9 @@ __always_inline bool free_pages_prepare(struct page *page, > > debug_pagealloc_unmap_pages(page, 1 << order); > > + if (anon && compound) > + mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); > + > return true; I'd have placed it here, when we are already passed the "PageMappingFlags" check and shouldn't have any added overhead for most !anon pages IIRC (mostly only anon/ksm pages should run into that path). diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 408ef3d25cf5..a11b9dd62964 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1079,8 +1079,11 @@ __always_inline bool free_pages_prepare(struct page *page, (page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; } } - if (PageMappingFlags(page)) + if (PageMappingFlags(page)) { + if (PageAnon(page) && compound) + mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); page->mapping = NULL; + } if (is_check_pages_enabled()) { if (free_page_is_bad(page)) bad++; Conceptually LGTM. We account an anon folio as long as it's anon, even when still GUP-pinned after unmapping it or when temporarily unmapping+remapping it during migration. -- Cheers, David / dhildenb