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[2003:d8:2f19:6500:e1c1:8216:4c25:efe4]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a4d9982c96sm2595262f8f.64.2025.05.26.05.23.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 May 2025 05:23:59 -0700 (PDT) Message-ID: <347b3035-26fe-43af-8df4-b1610d305908@redhat.com> Date: Mon, 26 May 2025 14:23:58 +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] mm/hugetlb: remove redundant folio_test_hugetlb From: David Hildenbrand To: yangge1116@126.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, 21cnbao@gmail.com, baolin.wang@linux.alibaba.com, muchun.song@linux.dev, osalvador@suse.de, liuzixing@hygon.cn References: <1747987559-23082-1-git-send-email-yangge1116@126.com> <427043ca-ae91-4386-8ffd-aaf164773226@redhat.com> 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: <427043ca-ae91-4386-8ffd-aaf164773226@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 26.05.25 14:20, David Hildenbrand wrote: > On 23.05.25 10:05, yangge1116@126.com wrote: >> From: Ge Yang >> >> In the isolate_or_dissolve_huge_folio() function, the folio_test_hugetlb() >> function is called to determine whether a folio is a hugetlb folio. >> However, in the subsequent alloc_and_dissolve_hugetlb_folio() function, >> the folio_test_hugetlb() function is called again to make the same >> determination about whether the folio is a hugetlb folio. It appears that >> the folio_test_hugetlb() check in the isolate_or_dissolve_huge_folio() >> function can be removed. Additionally, a similar issue exists in the >> replace_free_hugepage_folios() function, and it should be addressed as >> well. >> >> Suggested-by: Oscar Salvador >> Signed-off-by: Ge Yang >> --- >> mm/hugetlb.c | 51 +++++++++++++-------------------------------------- >> 1 file changed, 13 insertions(+), 38 deletions(-) >> >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >> index 6c2e007..6e46f2f 100644 >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -2787,20 +2787,24 @@ void restore_reserve_on_error(struct hstate *h, struct vm_area_struct *vma, >> /* >> * alloc_and_dissolve_hugetlb_folio - Allocate a new folio and dissolve >> * the old one >> - * @h: struct hstate old page belongs to >> * @old_folio: Old folio to dissolve >> * @list: List to isolate the page in case we need to >> * Returns 0 on success, otherwise negated error. >> */ >> -static int alloc_and_dissolve_hugetlb_folio(struct hstate *h, >> - struct folio *old_folio, struct list_head *list) >> +static int alloc_and_dissolve_hugetlb_folio(struct folio *old_folio, >> + struct list_head *list) >> { >> - gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE; >> + gfp_t gfp_mask; >> + struct hstate *h; >> int nid = folio_nid(old_folio); >> struct folio *new_folio = NULL; >> int ret = 0; >> >> retry: >> + /* >> + * The old_folio might have been dissolved from under our feet, so make sure >> + * to carefully check the state under the lock. >> + */ >> spin_lock_irq(&hugetlb_lock); >> if (!folio_test_hugetlb(old_folio)) { >> /* >> @@ -2829,8 +2833,10 @@ static int alloc_and_dissolve_hugetlb_folio(struct hstate *h, >> cond_resched(); >> goto retry; >> } else { >> + h = folio_hstate(old_folio); >> if (!new_folio) { >> spin_unlock_irq(&hugetlb_lock); >> + gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE; >> new_folio = alloc_buddy_hugetlb_folio(h, gfp_mask, nid, >> NULL, NULL); >> if (!new_folio) >> @@ -2874,35 +2880,20 @@ static int alloc_and_dissolve_hugetlb_folio(struct hstate *h, >> >> int isolate_or_dissolve_huge_folio(struct folio *folio, struct list_head *list) >> { >> - struct hstate *h; >> int ret = -EBUSY; >> >> /* >> - * The page might have been dissolved from under our feet, so make sure >> - * to carefully check the state under the lock. >> - * Return success when racing as if we dissolved the page ourselves. >> - */ >> - spin_lock_irq(&hugetlb_lock); >> - if (folio_test_hugetlb(folio)) { >> - h = folio_hstate(folio); >> - } else { >> - spin_unlock_irq(&hugetlb_lock); >> - return 0; >> - } >> - spin_unlock_irq(&hugetlb_lock); >> - >> - /* >> * Fence off gigantic pages as there is a cyclic dependency between >> * alloc_contig_range and them. Return -ENOMEM as this has the effect >> * of bailing out right away without further retrying. >> */ >> - if (hstate_is_gigantic(h)) >> + if (folio_order(folio) > MAX_PAGE_ORDER) >> return -ENOMEM; >> >> if (folio_ref_count(folio) && folio_isolate_hugetlb(folio, list)) >> ret = 0; >> else if (!folio_ref_count(folio)) >> - ret = alloc_and_dissolve_hugetlb_folio(h, folio, list); >> + ret = alloc_and_dissolve_hugetlb_folio(folio, list); >> >> return ret; >> } >> @@ -2916,7 +2907,6 @@ int isolate_or_dissolve_huge_folio(struct folio *folio, struct list_head *list) >> */ >> int replace_free_hugepage_folios(unsigned long start_pfn, unsigned long end_pfn) >> { >> - struct hstate *h; >> struct folio *folio; >> int ret = 0; >> >> @@ -2925,23 +2915,8 @@ int replace_free_hugepage_folios(unsigned long start_pfn, unsigned long end_pfn) >> while (start_pfn < end_pfn) { >> folio = pfn_folio(start_pfn); >> >> - /* >> - * The folio might have been dissolved from under our feet, so make sure >> - * to carefully check the state under the lock. >> - */ >> - spin_lock_irq(&hugetlb_lock); >> - if (folio_test_hugetlb(folio)) { >> - h = folio_hstate(folio); >> - } else { >> - spin_unlock_irq(&hugetlb_lock); >> - start_pfn++; >> - continue; >> - } >> - spin_unlock_irq(&hugetlb_lock); > > ^ oh my, that is bad code. > > Taking the hugetlb_lock for each and ever page in the range. > > Let me find that code and nack it. Already in 6.15, gah. Please convert that code to never ever take any hugeglb locks unless we are clearly dealing with a hugetlb folios. -- Cheers, David / dhildenb