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[2003:d8:2f07:8700:71be:5385:87b8:5a98]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45a1c61a66esm201863575e9.0.2025.08.19.00.41.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 Aug 2025 00:41:41 -0700 (PDT) Message-ID: <4289fc02-8e09-4d33-a4a1-0e4b268b008c@redhat.com> Date: Tue, 19 Aug 2025 09:41:40 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] arm64/mm: Update create_kpti_ng_temp_pgd() to handle pgtable_alloc failure To: Chaitanya S Prakash , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Ryan Roberts , Yang Shi , Catalin Marinas , Will Deacon , Kevin Brodsky , Anshuman Khandual , Andrew Morton , Zhenhua Huang , Joey Gouly References: <20250813145607.1612234-1-chaitanyas.prakash@arm.com> <20250813145607.1612234-3-chaitanyas.prakash@arm.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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20250813145607.1612234-3-chaitanyas.prakash@arm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: d3C0FzPzetipQENYdq9AIR0o-MtHHW9vFx75vC75YEg_1755589303 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 32DF7140003 X-Stat-Signature: 57ofsanjkttswx56egqqme4dbh6o7pag X-HE-Tag: 1755589306-342397 X-HE-Meta: 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 s5xDuW4s jYS9rvQsSVrBUC2pg1HZFIIxJQy+y2voOzGMBzLirfzDRPohA9IFNLDwLsXXxrPQogacJheaRpLwnJw2Mard85DslGCSZ4fMF4HnOh3yNrRXInbSWDNAPE0E2QqzsmZPvmU341RCRfJbd8GY1SFkcg1gSX0lN+qC7FEdsnaWsiqHl/CpGxTpfjZr9Vu9dmVxQEFJRDUwH/q+k60E+i0wKS+h7uI+5He7HzxNxL0vk9FQr9TO9L9RehfARCNv0fwHv5B5wXuLsO5LL2T6ixSp55BDwdjOqlalGNMCFF/0pEQ5T7VqOlfukKQFh7fdS8dN9C7Dl/ByyB6TtOWmZJvd7xByebyclGp7hVLY3W6Q+aSgBxH70iQiEGgWxSjP5ejOsImOxLvPg1FO74Hi8HEa0RihZIc2J/rI5IxMjJsCtOwWHzoXNrDXwbhFz48lMSqYwnkbSjW73M2UrMZMGqifMbMLyVi/AKGG4pwfs 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 13.08.25 16:56, Chaitanya S Prakash wrote: > create_kpti_ng_temp_pgd() was created as an alias for void returning > __create_pgd_mapping_locked() and relied on pgtable_alloc() to BUG_ON() > if an allocation failure occurred. But as __create_pgd_mapping_locked() > has been updated as a part of the error propagation patch to return a > non-void value, update create_kpti_ng_temp_pgd() to act as a wrapper > around __create_pgd_mapping_locked() and BUG_ON() on ret being a non > zero value. If my memory serves me right, panic() is preferred in such unexpected early-boot scenarios (BUG_ON is frowned upon), where you can actually print what is going wrong. Which raises the question: could create_kpti_ng_temp_pgd() be __init? __kpti_install_ng_mappings(), the only caller, seems to be. -- Cheers David / dhildenb