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(p200300cbc748ba001c0048ea7b5ac12b.dip0.t-ipconnect.de. [2003:cb:c748:ba00:1c00:48ea:7b5a:c12b]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4215c2cd247sm176185215e9.40.2024.06.11.02.42.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 11 Jun 2024 02:42:57 -0700 (PDT) Message-ID: <824c319a-530e-4153-80f5-20e2c463fa81@redhat.com> Date: Tue, 11 Jun 2024 11:42:56 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/3] mm/memory_hotplug: initialize memmap of !ZONE_DEVICE with PageOffline() instead of PageReserved() To: linux-kernel@vger.kernel.org, Andrew Morton Cc: linux-mm@kvack.org, linux-hyperv@vger.kernel.org, virtualization@lists.linux.dev, xen-devel@lists.xenproject.org, kasan-dev@googlegroups.com, Mike Rapoport , Oscar Salvador , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Alexander Potapenko , Marco Elver , Dmitry Vyukov References: <20240607090939.89524-1-david@redhat.com> <20240607090939.89524-3-david@redhat.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: <20240607090939.89524-3-david@redhat.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-Queue-Id: 978EF10000A X-Rspam-User: X-Rspamd-Server: rspam08 X-Stat-Signature: 79cow7aakszsq8d8i3dq7hicdopba536 X-HE-Tag: 1718098984-647542 X-HE-Meta: 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 B1w4gnjy +7gqJox9jfvSyypIOI5wFjXdtV6PUMOqDRlwEsJQOYC0Y2qCtONDc9J7Bqwr4O+IQDejrSMhrKEb9k7Pj2KYKwJiuF2FxWN+AHeAE6jkQ+odoiWbBBHlFVbewoU1pKRocfocv1QwZZFXJ+9P4qgqcV3DQD5wmHSyN/eDyiDrwVKrqSClLCdn2/YMi1H4gWoLhRfKQuc6Q5hK7V/gtM3gVtpjzhnes+IurcaIRwbNY9to16vL+R1nELkUgPZBV+/ozpbIRskyzyaVavz3N7QAUjr7T4ZA5AvSnRbHYHQYBUbeikclUWLORawbPKu6hlf+swlW/D2TjKyxxaqbMsZh87XLZ0mUwlFms867aacLouL2sRpg6t1garXuilLAgBqBKmNUkqb9eOVfwLgVq+pktA5M//qhEN07ewZOeeZrU2O3TH+N0x212Axek+7OFHrCriF368UeUu1pSPSuhA8CKEaH2GA== 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 07.06.24 11:09, David Hildenbrand wrote: > We currently initialize the memmap such that PG_reserved is set and the > refcount of the page is 1. In virtio-mem code, we have to manually clear > that PG_reserved flag to make memory offlining with partially hotplugged > memory blocks possible: has_unmovable_pages() would otherwise bail out on > such pages. > > We want to avoid PG_reserved where possible and move to typed pages > instead. Further, we want to further enlighten memory offlining code about > PG_offline: offline pages in an online memory section. One example is > handling managed page count adjustments in a cleaner way during memory > offlining. > > So let's initialize the pages with PG_offline instead of PG_reserved. > generic_online_page()->__free_pages_core() will now clear that flag before > handing that memory to the buddy. > > Note that the page refcount is still 1 and would forbid offlining of such > memory except when special care is take during GOING_OFFLINE as > currently only implemented by virtio-mem. > > With this change, we can now get non-PageReserved() pages in the XEN > balloon list. From what I can tell, that can already happen via > decrease_reservation(), so that should be fine. > > HV-balloon should not really observe a change: partial online memory > blocks still cannot get surprise-offlined, because the refcount of these > PageOffline() pages is 1. > > Update virtio-mem, HV-balloon and XEN-balloon code to be aware that > hotplugged pages are now PageOffline() instead of PageReserved() before > they are handed over to the buddy. > > We'll leave the ZONE_DEVICE case alone for now. > @Andrew, can we add here: "Note that self-hosted vmemmap pages will no longer be marked as reserved. This matches ordinary vmemmap pages allocated from the buddy during memory hotplug. Now, really only vmemmap pages allocated from memblock during early boot will be marked reserved. Existing PageReserved() checks seem to be handling all relevant cases correctly even after this change." -- Cheers, David / dhildenb