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[2003:cb:c706:4e00:31ad:5274:e21c:b59]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42805730e68sm211104355e9.9.2024.07.30.03.26.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Jul 2024 03:26:25 -0700 (PDT) Message-ID: Date: Tue, 30 Jul 2024 12:26:24 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/4] mm: memory_hotplug: check hwpoisoned page firstly in do_migrate_range() To: Kefeng Wang , Andrew Morton Cc: Oscar Salvador , Miaohe Lin , Naoya Horiguchi , linux-mm@kvack.org References: <20240725011647.1306045-1-wangkefeng.wang@huawei.com> <20240725011647.1306045-3-wangkefeng.wang@huawei.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: <20240725011647.1306045-3-wangkefeng.wang@huawei.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 2F970100008 X-Stat-Signature: 1pduhxg1ufyyzy14pc88py5sik89icfn X-HE-Tag: 1722335189-544853 X-HE-Meta: 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 0NDLv8WA 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 25.07.24 03:16, Kefeng Wang wrote: > The commit b15c87263a69 ("hwpoison, memory_hotplug: allow hwpoisoned > pages to be offlined") don't handle the hugetlb pages, the dead loop > still occur if offline a hwpoison hugetlb, luckly, after the commit > e591ef7d96d6 ("mm,hwpoison,hugetlb,memory_hotplug: hotremove memory > section with hwpoisoned hugepage"), the HPageMigratable of hugetlb > page will be clear, and the hwpoison hugetlb page will be skipped in > scan_movable_pages(), so the deed loop issue is fixed. did you mean "endless loop" ? > > However if the HPageMigratable() check passed(without reference and > lock), the hugetlb page may be hwpoisoned, it won't cause issue since > the hwpoisoned page will be handled correctly in the next movable > pages scan loop, and it will be isolated in do_migrate_range() and > but fails to migrated. In order to avoid the unnecessary isolation and > unify all hwpoisoned page handling, let's unconditionally check hwpoison > firstly, and if it is a hwpoisoned hugetlb page, try to unmap it as > the catch all safety net like normal page does. But what's the benefit here besides slightly faster handling in an absolute corner case (I strongly suspect that we don't care)? > > Signed-off-by: Kefeng Wang > --- > mm/memory_hotplug.c | 27 ++++++++++++++++----------- > 1 file changed, 16 insertions(+), 11 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 66267c26ca1b..ccaf4c480aed 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1788,28 +1788,33 @@ static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) > folio = page_folio(page); > head = &folio->page; > > - if (PageHuge(page)) { > - pfn = page_to_pfn(head) + compound_nr(head) - 1; > - isolate_hugetlb(folio, &source); > - continue; > - } else if (PageTransHuge(page)) > - pfn = page_to_pfn(head) + thp_nr_pages(page) - 1; > - > /* > * HWPoison pages have elevated reference counts so the migration would > * fail on them. It also doesn't make any sense to migrate them in the > * first place. Still try to unmap such a page in case it is still mapped > - * (e.g. current hwpoison implementation doesn't unmap KSM pages but keep > - * the unmap as the catch all safety net). > + * (keep the unmap as the catch all safety net). > */ > - if (PageHWPoison(page)) { > + if (unlikely(PageHWPoison(page))) { We're not checking the head page here, will this work reliably for hugetlb? (I recall some difference in per-page hwpoison handling between hugetlb and THP due to the vmemmap optimization) -- Cheers, David / dhildenb