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[2003:cb:c721:b900:4f34:b2b7:739d:a650]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-371898aa8casm3251106f8f.93.2024.08.16.02.33.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 16 Aug 2024 02:33:38 -0700 (PDT) Message-ID: Date: Fri, 16 Aug 2024 11:33:37 +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] mm: Override mTHP "enabled" defaults at kernel cmdline To: Barry Song <21cnbao@gmail.com> Cc: akpm@linux-foundation.org, baohua@kernel.org, baolin.wang@linux.alibaba.com, corbet@lwn.net, ioworker0@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ryan.roberts@arm.com, v-songbaohua@oppo.com References: <6e23c705-3d67-419b-b085-f19f5101124c@redhat.com> <20240815235001.96624-1-21cnbao@gmail.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: <20240815235001.96624-1-21cnbao@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 16.08.24 01:50, Barry Song wrote: > On Thu, Aug 15, 2024 at 10:26 PM David Hildenbrand wrote: >> >>>>> +static inline int get_order_from_str(const char *size_str) >>>>> +{ >>>>> +     unsigned long size; >>>>> +     char *endptr; >>>>> +     int order; >>>>> + >>>>> +     size = memparse(size_str, &endptr); >>>> >>>> Do we have to also test if is_power_of_2(), and refuse if not? For >>>> example, what if someone would pass 3K, would the existing check catch it? >>> >>> no, the existing check can't catch it. >>> >>> I passed thp_anon=15K-64K:always, then I got 16K enabled: >>> >>> / # cat /sys/kernel/mm/transparent_hugepage/hugepages-16kB/enabled >>> [always] inherit madvise never >>> >> >> Okay, so we should document then that start/end of the range must be >> valid THP sizes. > > Ack > >> >>> I can actually check that by: >>> >>> static inline int get_order_from_str(const char *size_str) >>> { >>>       unsigned long size; >>>       char *endptr; >>>       int order; >>> >>>       size = memparse(size_str, &endptr); >>> >>>       if (!is_power_of_2(size >> PAGE_SHIFT)) >> >> No need for the shift. >> >> if (!is_power_of_2(size)) >> >> Is likely even more correct if someone would manage to pass something >> stupid like >> >> 16385 (16K + 1) > > Ack > >> >>>               goto err; >>>       order = get_order(size); >>>       if ((1 << order) & ~THP_ORDERS_ALL_ANON) >>>               goto err; >>> >>>       return order; >>> err: >>>       pr_err("invalid size %s in thp_anon boot parameter\n", size_str); >>>       return -EINVAL; >>> } >>> >>>> >>>>> +     order = fls(size >> PAGE_SHIFT) - 1; >>>> >>>> Is this a fancy way of writing >>>> >>>> order = log2(size >> PAGE_SHIFT); >>>> >>>> ? :) >>> >>> I think ilog2 is implemented by fls ? >> >> Yes, so we should have used that instead. But get_order() >> is even better. >> >>> >>>> >>>> Anyhow, if get_order() wraps that, all good. >>> >>> I guess it doesn't check power of 2? >>> >>>> >>>>> +     if ((1 << order) & ~THP_ORDERS_ALL_ANON) { >>>>> +             pr_err("invalid size %s(order %d) in thp_anon boot parameter\n", >>>>> +                     size_str, order); >>>>> +             return -EINVAL; >>>>> +     } >>>>> + >>>>> +     return order; >>>>> +} >>>> >>>> Apart from that, nothing jumped at me. >>> >>> Please take a look at the new get_order_from_str() before I >>> send v5 :-) >> >> Besides the shift for is_power_of_2(), LGTM, thanks! > > Thanks, David! > > Hi Andrew, > > Apologies for sending another squash request. If you'd > prefer me to send a new v5 that includes all the changes, > please let me know. > > > Don't shift the size, as it can still detect invalid sizes > like 16K+1. Also, document that the size must be a valid THP > size. > > diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst > index 15404f06eefd..4468851b6ecb 100644 > --- a/Documentation/admin-guide/mm/transhuge.rst > +++ b/Documentation/admin-guide/mm/transhuge.rst > @@ -294,8 +294,9 @@ kernel command line. > > Alternatively, each supported anonymous THP size can be controlled by > passing ``thp_anon=,[KMG]:;-[KMG]:``, > -where ```` is the THP size and ```` is one of ``always``, > -``madvise``, ``never`` or ``inherit``. > +where ```` is the THP size (must be a power of 2 of PAGE_SIZE and > +supported anonymous THP) and ```` is one of ``always``, ``madvise``, > +``never`` or ``inherit``. > > For example, the following will set 16K, 32K, 64K THP to ``always``, > set 128K, 512K to ``inherit``, set 256K to ``madvise`` and 1M, 2M > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index d6dade8ac5f6..903b47f2b2db 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -953,7 +953,7 @@ static inline int get_order_from_str(const char *size_str) > > size = memparse(size_str, &endptr); > > - if (!is_power_of_2(size >> PAGE_SHIFT)) > + if (!is_power_of_2(size)) > goto err; Reading your documentation above, do we also want to test "if (size < PAGE_SIZE)", or is that implicitly covered? (likely not I assume?) I assume it's implicitly covered: if we pass "1k" , it would be mapped to "4k" (order-0) and that is not a valid mTHP size, right? I would appreciate a quick v5, just so can see the final result more easily :) -- Cheers, David / dhildenb