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b=fh+FFf7aTtBW3HLDQPM/Z31aMG/zwVJqCGSrggC0sHVtwFqW5EyKzFVrxCylgySZx 7kbaXpr0lPywd4svkLcFf7otbi2RLLJ/hWUIomN9UYGlzzEMBMSNpnByjCmqW5SxmE zIvRsjbuInGsk1u6lzyetoJ8y9flRVCpBf5VxJ7HBwsQQTO9kZlnHZARkZLrvyyaC5 NY++nLjZs3x32kd0O9unk82mePtmw5V778hNAUpWRIXNj3yrXG41DZoI78sf3HkpK4 GgVmeQayQcKnQPvXhOka9SfD8AwxCZy3ux61gQ15KBR3zAM6uOGoB1neRZ/63B7T5K OFSSBCNR/vCoA== Message-ID: Date: Tue, 14 Apr 2026 10:07:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/pagewalk: honor action in pgd_entry and p4d_entry To: "Vlastimil Babka (SUSE)" , Cao Ruichuang , akpm@linux-foundation.org, ljs@kernel.org, Liam.Howlett@oracle.com, rppt@kernel.org, surenb@google.com, mhocko@suse.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260414051854.18487-1-create0818@163.com> <453f7de1-1ed7-4785-ab95-5d63dd4a3499@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: <453f7de1-1ed7-4785-ab95-5d63dd4a3499@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: CA2D0C0013 X-Stat-Signature: f4rjgofz6t7pxy5376gurnzi8t5n8ewm X-Rspam-User: X-HE-Tag: 1776154042-339790 X-HE-Meta: U2FsdGVkX1/k9guwYaFMXpGCaIkA4ZViEHvqRx+gcE4q85eu2xrLUDpgLisznbZAPdzAvxsnslVRoc5sEuz4Ksm2I6ti6DK/n5xyrXkXXIxwwop1fEKf5jhArzb8NTopzuLCfJlDDbzgnUSJpzOXdbEdIZfEZCIERTRRZSbBZVe66rsNx3AHVMuaqEyZrMjWvW0Zz7tX9cb7qVtefylXz2r2sq5zwpjwf0+vdLDNm3VtLv3CHEgf5fYMt5YbbRfOadCjkM4xIDxQIZv9Anq3uASQxWYvgp2utAJXkWwxFWD2D+hIRK+MkYXm445qvy68tJYlDqj4JzHAd7U/ED/u9gKcOmx2O4lVb6N8VaIvH8mleCbwKk0bwJETSV0W/Ft4PT0URp3KUfRRRFZmFdzV3/mxzsHw6hPBtquHzVfya5eQXspd7xGnMrDItCxfh3xOt59BCowuBsdNZ9A7gYxUmrRQkFfpejQP2cJJjTDGb8B3Ii4GPlfTEWkQ93/BYHa6eB/i3Og4gDyGKNueRgEgqFr4e4e0rHamHOQlwVOpLnY8GIQAT4WIBqPxNA5KlDMdKI7mUpQ/MtmvAJUduKPRuB8ufS/AjU1n4ALnFULkVE2E9wb4+tpv/FHjuMSPSfErH6G3gNkgwCw88BCrrnlcxwXWGXCo81fM2w3iMfu0R0fTzAlUjBXOnyGbBFcqsb3VZ+ERkVxWNwKhBvGa+8Uj6op2h9UkIIfGbM1FFqTBq/cPMrz8O39360vkmNSYr2ddwr40Tv1zyqgPjZw/X7aMn4iBDNWiGRklrzzddO9okx2rDv1NjzHXWRInrEmOZHb+cVyfyzAH4oFisHHURELKB/kt6uc7kiSBMgn1foO7YElk+B+YAnT3G/WkHzTuODCPVGuH+j70Fco4yEZz7beM4ZlWzKkSOpsIru1kDfBVzavMcM0JRJHoutMIftfUv8vF+468WkvK2T12RJ0xJ1p YxduPnvq 98uch86JJImjEEMpyJ1x5dMrw6HCA5SkIVTQfXx3FbpGWq67DBe/peloYCbecDHZ02+FxbRkm4nIWudiXHElxAEzJ1R0U3VU94axpxgJK+dAsMFv3YWJzBdqtwYNF2ry7pF+GswDTjKuoIDviA0hMxoUTwwpYMZe2AMiPq5yob/U/UrWZ6qIsM+Did3Sw5s1NfD9hjgEykM5MQGInhDcxv3MxHdsNWvpAFm8N1zGggEOn+tbPVSLFlXD+AmAHe6/8nNX72vIBj9ixuF0Y+sp9hWTHHEFt4wZZxOc0XfKA48kGrW2lcTK29xhpzQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/14/26 09:57, Vlastimil Babka (SUSE) wrote: > On 4/14/26 07:18, Cao Ruichuang wrote: >> walk_pud_range() and walk_pmd_range() reset walk->action to ACTION_SUBTREE and honor ACTION_CONTINUE/ACTION_AGAIN after invoking their callbacks, but walk_pgd_range() and walk_p4d_range() do not. >> >> That leaves the top levels with inconsistent callback semantics. In particular, ptdump sets ACTION_CONTINUE from pgd_entry() and p4d_entry() for leaf entries, but the generic walker still descends into lower levels instead of skipping the subtree. >> >> Initialize walk->action before calling pgd_entry() and p4d_entry(), and handle ACTION_CONTINUE and ACTION_AGAIN afterwards just like the lower page-table levels do. Also update the action comment to reflect that it applies to pgd_entry() and p4d_entry() as well. > > Your LLM has broken line wrapping. But it's ok, we're not interested in > patches produced by LLM reviewing code, with no human oversight and > understanding. NAK. Agreed. The educated reader would know that we never end up with p4d/pgd leaves in non-hugetlb VMAs. The ptdump code is overly cautious ;) -- Cheers, David