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[91.12.104.200]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4395a04f208sm204390315e9.6.2025.02.19.00.31.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 19 Feb 2025 00:31:23 -0800 (PST) Message-ID: <04f2a081-b267-42de-881f-14cb16ab0e3c@redhat.com> Date: Wed, 19 Feb 2025 09:31:22 +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 V4] mm/hugetlb: wait for hugetlb folios to be freed To: yangge1116@126.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, 21cnbao@gmail.com, baolin.wang@linux.alibaba.com, muchun.song@linux.dev, osalvador@suse.de, liuzixing@hygon.cn References: <1739936804-18199-1-git-send-email-yangge1116@126.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: <1739936804-18199-1-git-send-email-yangge1116@126.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 19.02.25 04:46, yangge1116@126.com wrote: > From: Ge Yang > > Since the introduction of commit c77c0a8ac4c52 ("mm/hugetlb: defer freeing > of huge pages if in non-task context"), which supports deferring the > freeing of hugetlb pages, the allocation of contiguous memory through > cma_alloc() may fail probabilistically. > > In the CMA allocation process, if it is found that the CMA area is occupied > by in-use hugetlb folios, these in-use hugetlb folios need to be migrated > to another location. When there are no available hugetlb folios in the > free hugetlb pool during the migration of in-use hugetlb folios, new folios > are allocated from the buddy system. A temporary state is set on the newly > allocated folio. Upon completion of the hugetlb folio migration, the > temporary state is transferred from the new folios to the old folios. > Normally, when the old folios with the temporary state are freed, it is > directly released back to the buddy system. However, due to the deferred > freeing of hugetlb pages, the PageBuddy() check fails, ultimately leading > to the failure of cma_alloc(). > > Here is a simplified call trace illustrating the process: > cma_alloc() > ->__alloc_contig_migrate_range() // Migrate in-use hugetlb folios > ->unmap_and_move_huge_page() > ->folio_putback_hugetlb() // Free old folios > ->test_pages_isolated() > ->__test_page_isolated_in_pageblock() > ->PageBuddy(page) // Check if the page is in buddy > > To resolve this issue, we have implemented a function named > wait_for_freed_hugetlb_folios(). This function ensures that the hugetlb > folios are properly released back to the buddy system after their migration > is completed. By invoking wait_for_freed_hugetlb_folios() before calling > PageBuddy(), we ensure that PageBuddy() will succeed. > > Fixes: c77c0a8ac4c52 ("mm/hugetlb: defer freeing of huge pages if in non-task context") > Signed-off-by: Ge Yang > Cc: > --- > > V4: > - add a check to determine if hpage_freelist is empty suggested by David > > V3: > - adjust code and message suggested by Muchun and David > > V2: > - flush all folios at once suggested by David > > include/linux/hugetlb.h | 5 +++++ > mm/hugetlb.c | 8 ++++++++ > mm/page_isolation.c | 10 ++++++++++ > 3 files changed, 23 insertions(+) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 6c6546b..0c54b3a 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -697,6 +697,7 @@ bool hugetlb_bootmem_page_zones_valid(int nid, struct huge_bootmem_page *m); > > int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list); > int replace_free_hugepage_folios(unsigned long start_pfn, unsigned long end_pfn); > +void wait_for_freed_hugetlb_folios(void); > struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, > unsigned long addr, bool cow_from_owner); > struct folio *alloc_hugetlb_folio_nodemask(struct hstate *h, int preferred_nid, > @@ -1092,6 +1093,10 @@ static inline int replace_free_hugepage_folios(unsigned long start_pfn, > return 0; > } > > +static inline void wait_for_freed_hugetlb_folios(void) > +{ > +} > + > static inline struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, > unsigned long addr, > bool cow_from_owner) > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 30bc34d..8801dbc 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -2955,6 +2955,14 @@ int replace_free_hugepage_folios(unsigned long start_pfn, unsigned long end_pfn) > return ret; > } > > +void wait_for_freed_hugetlb_folios(void) > +{ > + if (llist_empty(&hpage_freelist)) > + return; > + > + flush_work(&free_hpage_work); > +} > + > typedef enum { > /* > * For either 0/1: we checked the per-vma resv map, and one resv > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index 8ed53ee0..b2fc526 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -615,6 +615,16 @@ int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, > int ret; > > /* > + * Due to the deferred freeing of hugetlb folios, the hugepage folios may > + * not immediately release to the buddy system. This can cause PageBuddy() > + * to fail in __test_page_isolated_in_pageblock(). To ensure that the > + * hugetlb folios are properly released back to the buddy system, we > + * invoke the wait_for_freed_hugetlb_folios() function to wait for the > + * release to complete. > + */ > + wait_for_freed_hugetlb_folios(); > + > + /* > * Note: pageblock_nr_pages != MAX_PAGE_ORDER. Then, chunks of free > * pages are not aligned to pageblock_nr_pages. > * Then we just check migratetype first. Acked-by: David Hildenbrand -- Cheers, David / dhildenb