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[2003:cb:c739:8e00:7a46:1b8c:8b13:d3d]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-381eda03e42sm16074764f8f.89.2024.11.12.08.21.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Nov 2024 08:21:57 -0800 (PST) Message-ID: Date: Tue, 12 Nov 2024 17:21:56 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/5] mm: shmem: add large folio support for tmpfs From: David Hildenbrand To: Baolin Wang , akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, wangkefeng.wang@huawei.com, 21cnbao@gmail.com, ryan.roberts@arm.com, ioworker0@gmail.com, da.gomez@samsung.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: 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: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: LzJFOsX3VkllIXqYirqGaAZWZEg7dRpXwULrDGxv0MI_1731428519 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: rspam04 X-Rspamd-Queue-Id: A0FF4A0028 X-Stat-Signature: bj4gw4th4e9otics6gwsnswuny3tzhnp X-Rspam-User: X-HE-Tag: 1731428491-916564 X-HE-Meta: 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 7yRcduI3 spcjM3vniCFGfVngXT7EIdHqnDp3WG0Hfhfx79iIx0DIJul+uhevUOCMRO4tV6nVd2sRvOtpmoKlp/lszK+VWWDV4eTRj1JnsojQe/5rEOTFUtOneQNcLK2GnBvhV8bzg0jLRR/lJfMZ9g7r5iMF0e9vvXXXyr3mu7HbDYqownNE+Gc4MvEUAHGwtpnIWDkD8UOXFCwb2lRqew55i+t/Zu337e3kql5x2j0N/Ks1XUuW6aHKz3GkW94X0rqgjjlGW6RPf2dPymwVHBRXeo/0r+quNj9YPf7zpQqKTbUCOYKfdgKSX3IPfFNKb2ON37VJHbIC6zMiFltG7sinSNCO3Aqh46D/Njh8X4RO/gBXIsBL4EVRFCiGFRBBBFNw9jA5c8gIdlASO5Fs4wourk6w2XXIASr2TjcmdUPOll4YOP9lcQVyXjJjCGDnRlpOKtxyKU90u 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 12.11.24 17:19, David Hildenbrand wrote: > On 12.11.24 08:45, Baolin Wang wrote: >> Add large folio support for tmpfs write and fallocate paths matching the >> same high order preference mechanism used in the iomap buffered IO path >> as used in __filemap_get_folio(). >> >> Add shmem_mapping_size_orders() to get a hint for the orders of the folio >> based on the file size which takes care of the mapping requirements. >> >> Traditionally, tmpfs only supported PMD-sized huge folios. However nowadays >> with other file systems supporting any sized large folios, and extending >> anonymous to support mTHP, we should not restrict tmpfs to allocating only >> PMD-sized huge folios, making it more special. Instead, we should allow >> tmpfs can allocate any sized large folios. >> >> Considering that tmpfs already has the 'huge=' option to control the huge >> folios allocation, we can extend the 'huge=' option to allow any sized huge >> folios. The semantics of the 'huge=' mount option are: >> >> huge=never: no any sized huge folios >> huge=always: any sized huge folios >> huge=within_size: like 'always' but respect the i_size >> huge=advise: like 'always' if requested with fadvise()/madvise() >> >> Note: for tmpfs mmap() faults, due to the lack of a write size hint, still >> allocate the PMD-sized huge folios if huge=always/within_size/advise is set. >> >> Moreover, the 'deny' and 'force' testing options controlled by >> '/sys/kernel/mm/transparent_hugepage/shmem_enabled', still retain the same >> semantics. The 'deny' can disable any sized large folios for tmpfs, while >> the 'force' can enable PMD sized large folios for tmpfs. >> >> Co-developed-by: Daniel Gomez >> Signed-off-by: Daniel Gomez >> Signed-off-by: Baolin Wang >> --- >> mm/shmem.c | 91 +++++++++++++++++++++++++++++++++++++++++++++--------- >> 1 file changed, 77 insertions(+), 14 deletions(-) >> >> diff --git a/mm/shmem.c b/mm/shmem.c >> index 86b2e417dc6f..a3203cf8860f 100644 >> --- a/mm/shmem.c >> +++ b/mm/shmem.c >> @@ -549,10 +549,50 @@ static bool shmem_confirm_swap(struct address_space *mapping, >> >> static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER; >> >> +/** >> + * shmem_mapping_size_orders - Get allowable folio orders for the given file size. >> + * @mapping: Target address_space. >> + * @index: The page index. >> + * @write_end: end of a write, could extend inode size. >> + * >> + * This returns huge orders for folios (when supported) based on the file size >> + * which the mapping currently allows at the given index. The index is relevant >> + * due to alignment considerations the mapping might have. The returned order >> + * may be less than the size passed. >> + * >> + * Return: The orders. >> + */ >> +static inline unsigned int >> +shmem_mapping_size_orders(struct address_space *mapping, pgoff_t index, loff_t write_end) >> +{ >> + unsigned int order; >> + size_t size; >> + >> + if (!mapping_large_folio_support(mapping) || !write_end) >> + return 0; >> + >> + /* Calculate the write size based on the write_end */ >> + size = write_end - (index << PAGE_SHIFT); >> + order = filemap_get_order(size); >> + if (!order) >> + return 0; >> + >> + /* If we're not aligned, allocate a smaller folio */ >> + if (index & ((1UL << order) - 1)) >> + order = __ffs(index); >> + >> + order = min_t(size_t, order, MAX_PAGECACHE_ORDER); >> + return order > 0 ? BIT(order + 1) - 1 : 0; >> +} >> + >> static unsigned int shmem_huge_global_enabled(struct inode *inode, pgoff_t index, >> loff_t write_end, bool shmem_huge_force, >> + struct vm_area_struct *vma, >> unsigned long vm_flags) >> { >> + unsigned long within_size_orders; >> + unsigned int order; >> + pgoff_t aligned_index; >> loff_t i_size; >> >> if (HPAGE_PMD_ORDER > MAX_PAGECACHE_ORDER) > > We can allow all orders up to MAX_PAGECACHE_ORDER, > shmem_mapping_size_orders() handles it properly. > > So maybe we should drop this condition and use instead below where we have > > return BIT(HPAGE_PMD_ORDER); > > instead something like. > > return HPAGE_PMD_ORDER > MAX_PAGECACHE_ORDER ? 0 : BIT(HPAGE_PMD_ORDER); > > Ideally, factoring it out somehow > > > int maybe_pmd_order = HPAGE_PMD_ORDER > MAX_PAGECACHE_ORDER ? 0 : > BIT(HPAGE_PMD_ORDER); > > ... > > return maybe_pmd_order; > >> @@ -564,15 +604,41 @@ static unsigned int shmem_huge_global_enabled(struct inode *inode, pgoff_t index >> if (shmem_huge_force || shmem_huge == SHMEM_HUGE_FORCE) >> return BIT(HPAGE_PMD_ORDER); > > Why not force-enable all orders (of course, respecting > MAX_PAGECACHE_ORDER and possibly VMA)? > >> >> + /* >> + * The huge order allocation for anon shmem is controlled through >> + * the mTHP interface, so we still use PMD-sized huge order to >> + * check whether global control is enabled. >> + * >> + * For tmpfs mmap()'s huge order, we still use PMD-sized order to >> + * allocate huge pages due to lack of a write size hint. >> + * >> + * Otherwise, tmpfs will allow getting a highest order hint based on >> + * the size of write and fallocate paths, then will try each allowable >> + * huge orders. >> + */ >> switch (SHMEM_SB(inode->i_sb)->huge) { >> case SHMEM_HUGE_ALWAYS: >> - return BIT(HPAGE_PMD_ORDER); >> - case SHMEM_HUGE_WITHIN_SIZE: >> - index = round_up(index + 1, HPAGE_PMD_NR); >> - i_size = max(write_end, i_size_read(inode)); >> - i_size = round_up(i_size, PAGE_SIZE); >> - if (i_size >> PAGE_SHIFT >= index) >> + if (vma) >> return BIT(HPAGE_PMD_ORDER); >> + >> + return shmem_mapping_size_orders(inode->i_mapping, index, write_end); >> + case SHMEM_HUGE_WITHIN_SIZE: >> + if (vma) >> + within_size_orders = BIT(HPAGE_PMD_ORDER); >> + else >> + within_size_orders = shmem_mapping_size_orders(inode->i_mapping, >> + index, write_end); >> + >> + order = highest_order(within_size_orders); >> + while (within_size_orders) { >> + aligned_index = round_up(index + 1, 1 << order); >> + i_size = max(write_end, i_size_read(inode)); >> + i_size = round_up(i_size, PAGE_SIZE); >> + if (i_size >> PAGE_SHIFT >= aligned_index) >> + return within_size_orders; >> + >> + order = next_order(&within_size_orders, order); >> + } >> fallthrough; >> case SHMEM_HUGE_ADVISE: >> if (vm_flags & VM_HUGEPAGE) > > I think the point here is that "write" -> no VMA -> vm_flags == 0 -> no > code changes needed :) ... and now I wonder about documented "fadvise", because this here is only concerned with madvise? -- Cheers, David / dhildenb