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Fri, 12 Jul 2024 21:17:38 -0700 (PDT) Message-ID: <11c95a82-cf13-414b-b489-1dd48255e022@redhat.com> Date: Sat, 13 Jul 2024 06:17:37 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/huge_memory: Avoid PMD-size page cache if needed To: Baolin Wang , Gavin Shan , Matthew Wilcox Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, william.kucharski@oracle.com, ryan.roberts@arm.com, shan.gavin@gmail.com References: <20240711104840.200573-1-gshan@redhat.com> <63a0364b-a2e0-48c2-b255-e976112deeb1@redhat.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: 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: 8bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 649F680010 X-Stat-Signature: cmdy6iyn5fztusowoppx7zy3gh6afu4p X-Rspam-User: X-HE-Tag: 1720844263-418882 X-HE-Meta: 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 Y5rryARG 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 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 13.07.24 06:01, Baolin Wang wrote: > > > On 2024/7/13 09:03, David Hildenbrand wrote: >> On 12.07.24 07:39, Gavin Shan wrote: >>> On 7/12/24 7:03 AM, David Hildenbrand wrote: >>>> On 11.07.24 22:46, Matthew Wilcox wrote: >>>>> On Thu, Jul 11, 2024 at 08:48:40PM +1000, Gavin Shan wrote: >>>>>> +++ b/mm/huge_memory.c >>>>>> @@ -136,7 +136,8 @@ unsigned long __thp_vma_allowable_orders(struct >>>>>> vm_area_struct *vma, >>>>>>            while (orders) { >>>>>>                addr = vma->vm_end - (PAGE_SIZE << order); >>>>>> -            if (thp_vma_suitable_order(vma, addr, order)) >>>>>> +            if (!(vma->vm_file && order > MAX_PAGECACHE_ORDER) && >>>>>> +                thp_vma_suitable_order(vma, addr, order)) >>>>>>                    break; >>>>> >>>>> Why does 'orders' even contain potential orders that are larger than >>>>> MAX_PAGECACHE_ORDER? >>>>> >>>>> We do this at the top: >>>>> >>>>>           orders &= vma_is_anonymous(vma) ? >>>>>                           THP_ORDERS_ALL_ANON : THP_ORDERS_ALL_FILE; >>>>> >>>>> include/linux/huge_mm.h:#define THP_ORDERS_ALL_FILE >>>>> (BIT(PMD_ORDER) | BIT(PUD_ORDER)) >>>>> >>>>> ... and that seems very wrong.  We support all kinds of orders for >>>>> files, not just PMD order.  We don't support PUD order at all. >>>>> >>>>> What the hell is going on here? >>>> >>>> yes, that's just absolutely confusing. I mentioned it to Ryan lately >>>> that we should clean that up (I wanted to look into that, but am >>>> happy if someone else can help). >>>> >>>> There should likely be different defines for >>>> >>>> DAX (PMD|PUD) >>>> >>>> SHMEM (PMD) -- but soon more. Not sure if we want separate ANON_SHMEM >>>> for the time being. Hm. But shmem is already handles separately, so >>>> maybe we can just ignore shmem here. >>>> >>>> PAGECACHE (1 .. MAX_PAGECACHE_ORDER) >>>> >>>> ? But it's still unclear to me. >>>> >>>> At least DAX must stay special I think, and PAGECACHE should be >>>> capped at MAX_PAGECACHE_ORDER. >>>> >>> >>> David, I can help to clean it up. Could you please help to confirm the >>> following >> >> Thanks! >> >>> changes are exactly what you're suggesting? Hopefully, there are >>> nothing I've missed. >>> The original issue can be fixed by the changes. With the changes >>> applied, madvise(MADV_COLLAPSE) >>> returns with errno -22 in the test program. >>> >>> The fix tag needs to adjusted either. >>> >>> Fixes: 3485b88390b0 ("mm: thp: introduce multi-size THP sysfs interface") >>> >>> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h >>> index 2aa986a5cd1b..45909efb0ef0 100644 >>> --- a/include/linux/huge_mm.h >>> +++ b/include/linux/huge_mm.h >>> @@ -74,7 +74,12 @@ extern struct kobj_attribute shmem_enabled_attr; >>>    /* >>>     * Mask of all large folio orders supported for file THP. >>>     */ >>> -#define THP_ORDERS_ALL_FILE    (BIT(PMD_ORDER) | BIT(PUD_ORDER)) >> >> DAX doesn't have any MAX_PAGECACHE_ORDER restrictions (like hugetlb). So >> this should be >> >> /* >>  * FSDAX never splits folios, so the MAX_PAGECACHE_ORDER limit does not >>  * apply here. >>  */ >> THP_ORDERS_ALL_FILE_DAX ((BIT(PMD_ORDER) | BIT(PUD_ORDER)) >> >> Something like that >> >>> +#define THP_ORDERS_ALL_FILE_DAX                \ >>> +       ((BIT(PMD_ORDER) | BIT(PUD_ORDER)) & (BIT(MAX_PAGECACHE_ORDER >>> + 1) - 1)) >>> +#define THP_ORDERS_ALL_FILE_DEFAULT    \ >>> +       ((BIT(MAX_PAGECACHE_ORDER + 1) - 1) & ~BIT(0)) >>> +#define THP_ORDERS_ALL_FILE            \ >>> +       (THP_ORDERS_ALL_FILE_DAX | THP_ORDERS_ALL_FILE_DEFAULT) >> >> Maybe we can get rid of THP_ORDERS_ALL_FILE (to prevent abuse) and fixup >> THP_ORDERS_ALL instead. >> >>>    /* >>>     * Mask of all large folio orders supported for THP. >>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >>> index 2120f7478e55..4690f33afaa6 100644 >>> --- a/mm/huge_memory.c >>> +++ b/mm/huge_memory.c >>> @@ -88,9 +88,17 @@ unsigned long __thp_vma_allowable_orders(struct >>> vm_area_struct *vma, >>>           bool smaps = tva_flags & TVA_SMAPS; >>>           bool in_pf = tva_flags & TVA_IN_PF; >>>           bool enforce_sysfs = tva_flags & TVA_ENFORCE_SYSFS; >>> +       unsigned long supported_orders; >>> + >>>           /* Check the intersection of requested and supported orders. */ >>> -       orders &= vma_is_anonymous(vma) ? >>> -                       THP_ORDERS_ALL_ANON : THP_ORDERS_ALL_FILE; >>> +       if (vma_is_anonymous(vma)) >>> +               supported_orders = THP_ORDERS_ALL_ANON; >>> +       else if (vma_is_dax(vma)) >>> +               supported_orders = THP_ORDERS_ALL_FILE_DAX; >>> +       else >>> +               supported_orders = THP_ORDERS_ALL_FILE_DEFAULT; >> >> This is what I had in mind. >> >> But, do we have to special-case shmem as well or will that be handled >> correctly? > > For anonymous shmem, it is now same as anonymous THP, which can utilize > THP_ORDERS_ALL_ANON. > For tmpfs, we currently only support PMD-sized THP > (will support more larger orders in the future). Therefore, I think we > can reuse THP_ORDERS_ALL_ANON for shmem now: > > if (vma_is_anonymous(vma) || shmem_file(vma->vm_file))) > supported_orders = THP_ORDERS_ALL_ANON; > ...... > It should be THP_ORDERS_ALL_FILE_DEFAULT (MAX_PAGECACHE_ORDER imitation applies). -- Cheers, David / dhildenb