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[149.14.88.26]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ae35363b369sm1223317466b.3.2025.07.03.02.06.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 03 Jul 2025 02:06:34 -0700 (PDT) Message-ID: <7b2c054b-fc33-4127-aaa9-9edf6a63e142@redhat.com> Date: Thu, 3 Jul 2025 11:06:34 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] mm/memory_hotplug: fix hwpoisoned large folio handling in do_migrate_range To: Jinjiang Tu , Oscar Salvador Cc: akpm@linux-foundation.org, linmiaohe@huawei.com, mhocko@kernel.org, linux-mm@kvack.org, wangkefeng.wang@huawei.com References: <20250627125747.3094074-1-tujinjiang@huawei.com> <20250627125747.3094074-3-tujinjiang@huawei.com> <373d02c5-2b62-8543-b786-8fd591ad56eb@huawei.com> <61325284-d1d6-a973-8aa7-c0f226db95fa@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: <61325284-d1d6-a973-8aa7-c0f226db95fa@huawei.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: jG7Lm4eaFdZJmSwsb7Lrvd76QioBWODRfnCOa_GmjuM_1751533596 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A16D780004 X-Stat-Signature: aaesaxgocxdg4awqzaoyropwn4pms58w X-HE-Tag: 1751533599-100352 X-HE-Meta: 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 hx70/xdW t/OfxQf0uY7ParmirPWiWJIA856pYsZFC28b4QDlg4IvfT+4M6qBwBBJgxeeRU7zj1ve3WijuHDdaTdO9ij+snGd9JFN2ZVWt1DNjfIsZJIYcQV6O2n1bBnQkKqma+z0wb/Sv9QAMo7m/NGBSA/tnAMJYxOywFWMudJIuuTUt9f+VujtedU9vClt45Itg0zmX6esaSsfFfIp885si+dfDMXLhQSOccWwDfLOwsorZ26zFdioD9SeKCJBCVlR0Dd7/JW6QQ6Qy3j2pspb/82vvSLPfDkoUkoJJAtQoKdQyz5UsOh7WzYiWUSVmx8nCvD1to3FEyGfVQVCG5OsAEKcW4712UC6XHJrx+jgSzIssUk/uXmVV07HZWuSwLrvqTxpzB27wk6l05QXRD/ARPbG+D6SZtN13HBuLV+DBxsZsemZ4cas538vWbi8olNGxmOVYVTBTMXt5cwNQDiiHETRN97Bvz/pKRONfhTlSTCRP3lgWkVHEG265E8YmrCdpa4bY+GPensgeG8x2Skc= 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 03.07.25 10:24, Jinjiang Tu wrote: > > 在 2025/7/3 15:57, David Hildenbrand 写道: >> On 03.07.25 09:46, Jinjiang Tu wrote: >>> >>> 在 2025/7/1 22:21, Oscar Salvador 写道: >>>> On Fri, Jun 27, 2025 at 08:57:47PM +0800, Jinjiang Tu wrote: >>>>> In do_migrate_range(), the hwpoisoned folio may be large folio, which >>>>> can't be handled by unmap_poisoned_folio(). >>>>> >>>>> I can reproduce this issue in qemu after adding delay in >>>>> memory_failure() >>>>> >>>>> BUG: kernel NULL pointer dereference, address: 0000000000000000 >>>>> Workqueue: kacpi_hotplug acpi_hotplug_work_fn >>>>> RIP: 0010:try_to_unmap_one+0x16a/0xfc0 >>>>>    >>>>>    rmap_walk_anon+0xda/0x1f0 >>>>>    try_to_unmap+0x78/0x80 >>>>>    ? __pfx_try_to_unmap_one+0x10/0x10 >>>>>    ? __pfx_folio_not_mapped+0x10/0x10 >>>>>    ? __pfx_folio_lock_anon_vma_read+0x10/0x10 >>>>>    unmap_poisoned_folio+0x60/0x140 >>>>>    do_migrate_range+0x4d1/0x600 >>>>>    ? slab_memory_callback+0x6a/0x190 >>>>>    ? notifier_call_chain+0x56/0xb0 >>>>>    offline_pages+0x3e6/0x460 >>>>>    memory_subsys_offline+0x130/0x1f0 >>>>>    device_offline+0xba/0x110 >>>>>    acpi_bus_offline+0xb7/0x130 >>>>>    acpi_scan_hot_remove+0x77/0x290 >>>>>    acpi_device_hotplug+0x1e0/0x240 >>>>>    acpi_hotplug_work_fn+0x1a/0x30 >>>>>    process_one_work+0x186/0x340 >>>>> >>>>> In this case, just make offline_pages() fail. >>>>> >>>>> Besides, do_migrate_range() may be called between memory_failure set >>>>> hwposion flag and ioslate the folio from lru, so remove WARN_ON(). >>>>> In other >>>>> places, unmap_poisoned_folio() is called when the folio is >>>>> isolated, obey >>>>> it in do_migrate_range() too. >>>>> >>>>> Fixes: b15c87263a69 ("hwpoison, memory_hotplug: allow hwpoisoned >>>>> pages to be offlined") >>>>> Signed-off-by: Jinjiang Tu >>>> ... >>>>> @@ -2041,11 +2048,9 @@ int offline_pages(unsigned long start_pfn, >>>>> unsigned long nr_pages, >>>>>                   ret = scan_movable_pages(pfn, end_pfn, &pfn); >>>>>                if (!ret) { >>>>> -                /* >>>>> -                 * TODO: fatal migration failures should bail >>>>> -                 * out >>>>> -                 */ >>>>> -                do_migrate_range(pfn, end_pfn); >>>>> +                ret = do_migrate_range(pfn, end_pfn); >>>>> +                if (ret) >>>>> +                    break; >>>> I am not really sure about this one. >>>> I get the reason you're adding it, but note that migrate_pages() can >>>> also return >>>> "fatal" errors and we don't propagate that. >>>> >>>> The moto has always been to migrate as much as possible, and this >>>> changes this >>>> behaviour. >>> If we just skip to next pfn, offline_pages() will deadloop meaningless >>> util received signal. >> >> Yeah, that's also not good, >> >>> It seems there is no document to guarantee memory offline have to >>> migrate as much as possible. >> >> We should try offlining as good as possible. But if there is something >> we just cannot possibly migrate, there is no sense in retrying. >> >> Now, could we run into this case here because we are racing with other >> code, and actually retrying again could make it work? >> >> Remind me again: how exactly do we arrive at this point of having a >> large folio that is hwpoisoned but still mapped? >> >> In memory_failure(), we do on a  large folio >> >> 1) folio_set_has_hwpoisoned >> 2) try_to_split_thp_page >> 3) if splitting fails, kill_procs_now > If 2) is executed when do_migrate_range() increment the refcount of the > folio, the split fails, and retry is meaningless. kill_procs_now will kill all processes, effectively unmapping the folio in that case? So retrying would later just ... get us an unmapped folio and we can make progress? -- Cheers, David / dhildenb