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[2003:cb:c724:4300:430f:1c83:1abc:1d66]) by smtp.gmail.com with ESMTPSA id i4-20020a5d6304000000b003437ad152f9sm2703535wru.105.2024.04.11.14.56.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 11 Apr 2024 14:56:19 -0700 (PDT) Message-ID: <3dbf706f-b6ca-45d7-a293-12aa5807fcdf@redhat.com> Date: Thu, 11 Apr 2024 23:56:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 0/2] s390/mm: shared zeropage + KVM fixes To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Peter Xu , Alexander Gordeev , Sven Schnelle , Gerald Schaefer , Andrea Arcangeli , kvm@vger.kernel.org, linux-s390@vger.kernel.org References: <20240411161441.910170-1-david@redhat.com> <20240411142827.d5c3bc401c6536bb1315049a@linux-foundation.org> 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: <20240411142827.d5c3bc401c6536bb1315049a@linux-foundation.org> 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-Stat-Signature: 45m9ykkh3ubuaj8zicgny7epzd911uqa X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 9965F100014 X-Rspam-User: X-HE-Tag: 1712872583-278749 X-HE-Meta: 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 XEAhAK5h 3fUHy58IKvXvvXKYT1HwerygHQOh8C5KBCEP4umwXQK1UyU2EWAKpXdNgj/WKnRwXjr23SRmHwIzTDjP/EKJXLwUHqTVKB7m4Nj6kIPEIs+EhgvplMcliFrBl4D1JnwQVaWfCqBAw/qK1IDnHebA2uwiZ2iOsJkT8V8EsutZH8DOnF3Hag5kNjPbF5HmkgjHv9udLd+fzOfLGJWhRg0sz+JjYD3mbIEDh/g+N 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 11.04.24 23:28, Andrew Morton wrote: > On Thu, 11 Apr 2024 18:14:39 +0200 David Hildenbrand wrote: > >> This series fixes one issue with uffd + shared zeropages on s390x and >> fixes that "ordinary" KVM guests can make use of shared zeropages again. >> >> ... >> >> Without the shared zeropage, during (2), the VM would suddenly consume >> 100 GiB on the migration source and destination. On the migration source, >> where we don't excpect memory overcommit, we could easilt end up crashing >> the VM during migration. >> >> Independent of that, memory handed back to the hypervisor using "free page >> reporting" would end up consuming actual memory after the migration on the >> destination, not getting freed up until reused+freed again. >> > > Is a backport desirable? > > If so, the [1/2] Fixes dates back to 2015 and the [2/2] Fixes is from > 2017. Is it appropriate that the patches be backported so far back, > and into different kernel versions? > [2/2] won't be easy to backport to kernels without FAULT_FLAG_UNSHARE, so I wouldn't really suggest backports to kernels before that. [1/2] might be reasonable to backport, but might require some tweaking (page vs. folio). -- Cheers, David / dhildenb