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[2003:cb:c72f:f700:104b:9184:1b45:1898]) by smtp.gmail.com with ESMTPSA id q2-20020adfab02000000b0033cf5094fcesm7549356wrc.36.2024.02.26.00.41.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 Feb 2024 00:41:34 -0800 (PST) Message-ID: <9bcf5141-7376-441e-bbe3-779956ef28b9@redhat.com> Date: Mon, 26 Feb 2024 09:41:33 +0100 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 1/1] mm/madvise: enhance lazyfreeing with mTHP in madvise_free Content-Language: en-US To: Lance Yang , 21cnbao@gmail.com Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, minchan@kernel.org, peterx@redhat.com, ryan.roberts@arm.com, shy828301@gmail.com, songmuchun@bytedance.com, wangkefeng.wang@huawei.com, zokeefe@google.com, fengwei.yin@intel.com References: <20240226083714.26187-1-ioworker0@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: <20240226083714.26187-1-ioworker0@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 26.02.24 09:37, Lance Yang wrote: > Hey Barry, > > Thanks for taking time to review! > > On Mon, Feb 26, 2024 at 12:00 PM Barry Song <21cnbao@gmail.com> wrote: > [...] >> On Mon, Feb 26, 2024 at 1:33 AM Lance Yang wrote: > [...] >> We did something similar on MADV_PAGEOUT[1] >> [1] https://lore.kernel.org/linux-mm/20240118111036.72641-7-21cnbao@gmail.com/ > > Thanks for providing the link above. > > [...] >>> +                        * Avoid unnecessary folio splitting if the large >>> +                        * folio is entirely within the given range. >>> +                        */ >>> +                       folio_test_clear_dirty(folio); >>> +                       folio_unlock(folio); >>> +                       for (; addr != next_addr; pte++, addr += PAGE_SIZE) { >>> +                               ptent = ptep_get(pte); >>> +                               if (pte_young(ptent) || pte_dirty(ptent)) { >>> +                                       ptent = ptep_get_and_clear_full( >>> +                                               mm, addr, pte, tlb->fullmm); >>> +                                       ptent = pte_mkold(ptent); >>> +                                       ptent = pte_mkclean(ptent); >>> +                                       set_pte_at(mm, addr, pte, ptent); >>> +                                       tlb_remove_tlb_entry(tlb, pte, addr); >>> +                               } >> >> The code works under the assumption the large folio is entirely mapped >> in all PTEs in the range. This is not always true. >> >> This won't work in some cases as some PTEs might be mapping to the >> large folios. some others might have been unmapped or mapped >> to different folios. >> >> so in MADV_PAGEOUT, we have a function to check the folio is >> really entirely mapped: >> >> +static inline bool pte_range_cont_mapped(unsigned long start_pfn, >> + pte_t *start_pte, unsigned long start_addr, int nr) >> +{ >> + int i; >> + pte_t pte_val; >> + >> + for (i = 0; i < nr; i++) { >> + pte_val = ptep_get(start_pte + i); >> + >> + if (pte_none(pte_val)) >> + return false; >> + >> + if (pte_pfn(pte_val) != (start_pfn + i)) >> + return false; >> + } >> + >> + return true; >> +} > > Thanks for providing the information; it's very helpful to me! > I made some changes. Would you mind taking another look, please? > > As a diff against this patch. > > diff --git a/mm/madvise.c b/mm/madvise.c > index bcbf56595a2e..255d2f329be4 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -616,6 +616,18 @@ static long madvise_pageout(struct vm_area_struct *vma, > return 0; > } > > +static inline bool pte_range_cont_mapped(pte_t *pte, unsigned long nr) > +{ > + pte_t pte_val; > + unsigned long pfn = pte_pfn(pte); > + for (int i = 0; i < nr; i++) { > + pte_val = ptep_get(pte + i); > + if (pte_none(pte_val) || pte_pfn(pte_val) != (pfn + i)) > + return false; > + } > + return true; > +} I dislike the "cont mapped" terminology. Maybe folio_pte_batch() does what you want? -- Cheers, David / dhildenb