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b=kIdLQ3obujLEplnrv+jkqgccCFd1D+wekSsoKKeRVxq80FUf2iFHPBipViZo/dXW9 y1ET3yZgrUSmUaN8Bb/Qypty2L5rzXf8S68UhZgJLjqxgEUlotzWXrqV9XsrdvQWT5 FHynNmxIcfiCL9HnuUa/UCKSCVr6RMPptdukwKOl94rN0ISUMn1xrTu7CkvQ8Hom+N MNQKqJzaAhs2WZDHpV1Q+JQKAy3CZxghj04bLBcb2PkWq9g0xX1EZxZscGHZbNfRv+ w+HHVNvNG7qir8DdWuko87cWdFx/G8hJMMU1Ws792PDSQEBXlleqDsRvJn0yfFF2kV MHWV6y0Q8A81w== Message-ID: Date: Tue, 14 Apr 2026 11:46:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/migrate_device: fix double unlock and remove dead code To: Matthew Brost , Sunny Patel Cc: Andrew Morton , Zi Yan , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260413130927.13263-1-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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: sx3akh7wy1dnasohfn4j6mcd43911b6d X-Rspamd-Queue-Id: 1219DC000D X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1776159999-52385 X-HE-Meta: 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 jubdImuw wLXdeBDbtKuWbEaijmp7nyV9UjBA1btprgDQMULz31frZJYuO1cg3ExE7mpCv4IePTW5j8u8PbytTR8hZoXjF2sM4ter8lXANoXpSAvSU8W3gQkkmeOvWg+paPsq8PjrbCjvyEVxyZ3xjUteeOPAT7zTfOfBV0Gk3tk5KmuBpwTs//rynBD1B7SpM3IRfjRztwxa2HmHICpr5noyQE+pdZ0axJGzh3bfuOKJKwngvnMl/33ERmS6HpwodbifCsZQatzqp5SQyANabKkbZQ4QWfBiMOl0u48EmAsnr+NqWYxJcYWJtf3Zrj/srVT1f50Hgt7OKxe5J2+JhsMYslpSTxWJXD1XJSdL8XwJI1WgQe2HWpHxLqPjm5N0lOqdhNgpJxa/z6FS3FTJZ5SYHh/gg7HFnEMpcfXHo92bPLSMQeoRiNQFfrCbUTIQnIPJft9y4o+K2Qg9ztFAL33U= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/14/26 01:30, Matthew Brost wrote: > On Mon, Apr 13, 2026 at 06:39:23PM +0530, Sunny Patel wrote: >> Fix two bugs in device migration paths: >> >> 1) migrate_vma_collect_huge_pmd() calls spin_unlock after >> softleaf_entry_wait_on_locked(), which already releases the ptl. >> >> 2) migrate_vma_insert_huge_pmd_page() has a dead else-if branch and this >> branch is always unreachable. >> >> Signed-off-by: Sunny Patel >> --- >> mm/migrate_device.c | 4 +--- >> 1 file changed, 1 insertion(+), 3 deletions(-) >> >> diff --git a/mm/migrate_device.c b/mm/migrate_device.c >> index 8079676c8f1f..0e005c26ee88 100644 >> --- a/mm/migrate_device.c >> +++ b/mm/migrate_device.c >> @@ -177,7 +177,6 @@ static int migrate_vma_collect_huge_pmd(pmd_t *pmdp, unsigned long start, >> >> if (softleaf_is_migration(entry)) { >> softleaf_entry_wait_on_locked(entry, ptl); >> - spin_unlock(ptl); >> return -EAGAIN; >> } > > This entire if statement is dead code, since we bail out and collect a > skip on !softleaf_is_device_private immediately above. I thought we > already had a patch from Davidlohr Bueso 'mm/migrate_device: remove dead > migration entry check in migrate_vma_collect_huge_pmd()' that removed > this whole if statement. I even have an email from Andrew pulling this > patch, but it looks like the code is still present in 7.0. > > I found this link via a google search which contains the above patch > too: > > https://kernel.googlesource.com/pub/scm/linux/kernel/git/akpm/25-new/+/f405e7bc5d93a541cf11663b2424baf0a03b496f%5E%21/ > > Look like this change got lost somehow? Oh, even better, then we don't even need a Fixes: -- Cheers, David