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Tsirkin" Cc: linux-kernel@vger.kernel.org, Andrew Morton , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , linux-mm@kvack.org, virtualization@lists.linux.dev References: <20260420192037-mutt-send-email-mst@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 8DD0C100014 X-Stat-Signature: utpg5xk1si3sm33afe1h7cug68yh5ixc X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1776765896-284122 X-HE-Meta: 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 p5Oqq8pX t00dbVfdvZu1Q7bCqnMnN0Ex+rR1kaFMw5u0rxb4c9pVOVygEnHH5RYIZ7nkxI9XDSzU5llaDnkebXx7uu9JPxh4aeN/tCiXCnpX1Ddv67PCIyuw2MsMz5FEGIZU46UVaptjkJIEoJpdlOKLU07TwlK429/hIEFt9CVmmRuuka2lc5VySD4tAzPFw+pGKvuGGmwqstDmFubgjqMVM9FBYXRjyjBKgZDl7HHlMd7TvA30FJYFgaSDUHlR7XBNXdyj87t4u Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/21/26 04:38, Gregory Price wrote: > On Mon, Apr 20, 2026 at 07:33:38PM -0400, Michael S. Tsirkin wrote: >> On Mon, Apr 20, 2026 at 08:20:57PM +0200, David Hildenbrand (Arm) wrote: >> >>> >>> Which would *already* be the case of you use folio_alloc(GFP_ZERO) >>> instead of magical vma_alloc_folio() + folio_zero_user(). >>> >>> I don't really see how vma_alloc_folio_hints() -- that also consumes the >>> address -- is any better in that regard? >> >> By itself, it is not. But the issue is propagating the address from >> there all over mm. If we miss even one place - we get a subtle cache >> corruption on non x86. >> > > Why does it need to propogate? > > Can we leave folio_zero_user() callers the same, but add a PG_zeroed > check in folio_zero_user() that skips the zeroing (but not the cache > flush) and clear the PG_zeroed bit? folio_zero_user() is just an abomination, really. -- Cheers, David