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b=srQ8xjnMI5SNpZdbXO6SJXbCmehgQkh2pbyde5HNlB/onKRp9eeuD63KLLHIPQGSr ppK0GBStIybMhEfEWTbwxjDRE+/Js92e8OmF8PBO4CyJVqu9T1Hk0/PT9vybrnsQji PORhcHBKPLGg4WNV2oormglm1T6i2JAJrt3Gaq4Ts42UbYtKM7CplSgzVsQ5SjEt95 lz6Im6gzfU6l0pSWoUBGLMQUWMR8+AgcD303MMmfI7tbzmwL1LK85GbfyVRs0JbNc/ gsKg07U0qm+fK/QBHu5tmkYfqzKLeqpDK4kNtJTYJjpCRLvPyC6KeXrzyq9nkJx6WL C4Y826JVqRsdw== Message-ID: Date: Thu, 16 Apr 2026 21:44:15 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/migrate_device: Cleanup up PMD Checks and warnings To: Sunny Patel Cc: Andrew Morton , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260414141344.29949-1-nueralspacetech@gmail.com> 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: <20260414141344.29949-1-nueralspacetech@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1C77880004 X-Stat-Signature: isibpkbh4mszkcuc8wwtmos4ip84adtd X-Rspam-User: X-HE-Tag: 1776368661-324187 X-HE-Meta: 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 7gLmWzx2 sQ2G40df8WHGAf3RovRu0IaJbCvyCkTo+v8s428try9Zt3qARMNFw+ePZbZmthxYvbWz2JhrjQB+iEZFVruGtWShyvWE1uUbMUu1KLPg3Yd8uDIGavf8s6ywGkzOQalpOCitQ7zPIV/eqAQ6BkqXWoJ78oaNK3DCNhWZxiD7L8HfCPmA2lLt8cdklx+l/f41lLwltgEwqEkuCyUZXy7HNSGTLimB37oXjmJYzvB0iSNCk6A6MnrYs30+viYC3WNQYb6xwEhyMHdH1nMtrKs0WhlJVtDGmNXXOAYTH0k+z661r9vTGlk6DemrHsb1hx4myK7yTvutcEiz+OwzgFtAtAC9xqZIXuLl+EDb92exnhEXBLcIiaaQ8vpehsX81zTJHbeqt9jcLl8BT+Y7KpAwvdufBzf1hsGqNoxSWk/LjKyK0n9Q= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/14/26 16:13, Sunny Patel wrote: > Remove the odd VM_WARN_ON_FOLIO(!folio, folio) usage and replace it > with a simpler VM_WARN_ON_ONCE(!folio) check. > > Drop the redundant VM_WARN_ON_ONCE(!pmd_none(*pmdp) && > !is_huge_zero_pmd(*pmdp)). > > Refactor the PMD checks to use pmd_present(), making the control flow > clearer and avoiding duplicate condition checks. > > Signed-off-by: Sunny Patel > --- > mm/migrate_device.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/mm/migrate_device.c b/mm/migrate_device.c > index 8079676c8f1f..fe1c1999aa2d 100644 > --- a/mm/migrate_device.c > +++ b/mm/migrate_device.c > @@ -807,8 +807,7 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate, > bool flush = false; > unsigned long i; > > - VM_WARN_ON_FOLIO(!folio, folio); > - VM_WARN_ON_ONCE(!pmd_none(*pmdp) && !is_huge_zero_pmd(*pmdp)); > + VM_WARN_ON_ONCE(!folio); I'd test for "page" here instead. But it doesn't matter as of today. > > if (!thp_vma_suitable_order(vma, addr, HPAGE_PMD_ORDER)) > return -EINVAL; > @@ -865,12 +864,13 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate, > if (userfaultfd_missing(vma)) > goto unlock_abort; > > - if (!pmd_none(*pmdp)) { > + if (pmd_present(*pmdp)) { > if (!is_huge_zero_pmd(*pmdp)) > goto unlock_abort; > flush = true; > - } else if (!pmd_none(*pmdp)) > + } else if (!pmd_none(*pmdp)) { > goto unlock_abort; > + } > > add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); > folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE); is_huge_zero_pmd() checks pmd_present(), so we didn't have a bug before. We could also do: if (is_huge_zero_pmd(*pmdp)) { flush = true; } else if (!pmd_none(*pmdp)) { goto unlock_abort; } But I don't particularly care Acked-by: David Hildenbrand (Arm) -- Cheers, David