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[2003:d8:2f19:6500:e1c1:8216:4c25:efe4]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-447f7bae847sm230898175e9.36.2025.05.26.05.20.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 May 2025 05:20:08 -0700 (PDT) Message-ID: <427043ca-ae91-4386-8ffd-aaf164773226@redhat.com> Date: Mon, 26 May 2025 14:20:06 +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 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> 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: <1747987559-23082-1-git-send-email-yangge1116@126.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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. > - > if (!folio_ref_count(folio)) { > - ret = alloc_and_dissolve_hugetlb_folio(h, folio, > - &isolate_list); > + ret = alloc_and_dissolve_hugetlb_folio(folio, &isolate_list); And we're still doing that there now? We *really* should have an early folio_test_hugetlb() check and skip whatever has no indication of being related to hugetlb. -- Cheers, David / dhildenb