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b=lvRgPSgWAAdN4XQw3S2/yhtgm0ggA1Q019dIjUOymiLlfLatsBScYcJK0x4hRnETH /X8BeaWqBDCvY6Ng491iOaK7eJxS59eif9JSxCiMe/1sgAwo1jFVyGgKzFOPPHhXOu 9i6WyIW7f38b0Ddk67DZf7k+ECYL56wURose3Z6R5rjbSXl8qiCjTz0TpTKWdxOQZZ 0YTgIoHyvDcO5QgY447FEjSFduoYtWOExqC8LN9WmgoqcEUbNO4o+LTQyT690uejUV WzhTf/ZzWSJkdbOIH0xq131qlWB8m3G9ePzyg/RuD1N8DMbxrFuNLZI62jZbrOUvHP V7d5MRGyYWJJQ== Message-ID: Date: Mon, 7 Sep 2026 17:48:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] arm64/mm: Move __check_safe_pte_update() To: Anshuman Khandual , linux-arm-kernel@lists.infradead.org Cc: Mike Rapoport , Andrew Morton , Lorenzo Stoakes , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20260901065454.1906343-1-anshuman.khandual@arm.com> <20260901065454.1906343-2-anshuman.khandual@arm.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: <20260901065454.1906343-2-anshuman.khandual@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: BB77340006 X-Stat-Signature: dwoxome3naqmuhsbkiuhaenio5e85dr7 X-Rspam-User: X-HE-Tag: 1788796104-88236 X-HE-Meta: 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 pZDI0NVa SNSkt04lE4/d4T0E42qRZVRjWO/iHQO2Vt7iHu/At0h6nmOFJZqSZLJMK9+EcGf2n0u/WOAGap4XemmPoazKufecZ8MvkXsieaCrulCHb9lQeQHpNoxgiko3Mao2Vl87rj1FUOuz+eCVYqXGMQgio/KIF1Hhz0PbbzTyzXP1Zhhsi2jMsWugBJkBwFxHtqN+yTRq50QcWNYNlS2KUpyNIAGNsj7DtD03ep3n04V7V0surl+1ttCZvC9+NI38G9bp7ALb2iCeAV/qUSWZD3B2XeAo1hPNR7wZrt2t9PhgXp8Xr19fNsYC0ICS03BLmQDI8RYO/cxYqe18JKgsn2LUuqVgl/xbMJfXqcu0iJbzjC6vjIoHlW5e9hjMrb65lbng8XAPyVc+1l8EdHUGtzdJcBzfBAZQzdQBkr0GvehxzyKqFBUSWWjNsxveAxh58+AMENbAh2yPD+l6IFrIGamyVQ9fRFAOITskOFjxm Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/1/26 08:54, Anshuman Khandual wrote: > The page table entry print helpers and related macros which are defined in > will not be accessible in platform which > is basically caused by cycling dependency. > > Move __check_safe_pte_update() inside arch/arm64/mm/mmu.c as a preparation > for subsequent usage of the afore mentioned generic MM helpers. > > This does not cause any functional change. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual > --- > Should __check_safe_pte_update() be wrapped in #ifdef CONFIG_DEBUG_VM > along with dropping off current IS_ENABLED() test. That would ensure > the function never gets called when CONFIG_DEBUG_VM is disabled. That > will preserve current behaviour as the inline function gets dropped > when CONFIG_DEBUG_VM remains disabled. > > arch/arm64/include/asm/pgtable.h | 47 +------------------------------- > arch/arm64/mm/mmu.c | 45 ++++++++++++++++++++++++++++++ > 2 files changed, 46 insertions(+), 46 deletions(-) > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index e89ec5f4787b..61fbfab3e06e 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -387,52 +387,7 @@ static inline pte_t __ptep_get(pte_t *ptep) > extern void __sync_icache_dcache(pte_t pteval); > bool pgattr_change_is_safe(pteval_t old, pteval_t new); > > -/* > - * PTE bits configuration in the presence of hardware Dirty Bit Management > - * (PTE_WRITE == PTE_DBM): > - * > - * Dirty Writable | PTE_RDONLY PTE_WRITE PTE_DIRTY (sw) > - * 0 0 | 1 0 0 > - * 0 1 | 1 1 0 > - * 1 0 | 1 0 1 > - * 1 1 | 0 1 x > - * > - * When hardware DBM is not present, the software PTE_DIRTY bit is updated via > - * the page fault mechanism. Checking the dirty status of a pte becomes: > - * > - * PTE_DIRTY || (PTE_WRITE && !PTE_RDONLY) > - */ > - > -static inline void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, > - pte_t pte) > -{ > - pte_t old_pte; > - > - if (!IS_ENABLED(CONFIG_DEBUG_VM)) > - return; > - > - old_pte = __ptep_get(ptep); > - > - if (!pte_valid(old_pte) || !pte_valid(pte)) > - return; > - if (mm != current->active_mm && atomic_read(&mm->mm_users) <= 1) > - return; > - > - /* > - * Check for potential race with hardware updates of the pte > - * (__ptep_set_access_flags safely changes valid ptes without going > - * through an invalid entry). > - */ > - VM_WARN_ONCE(!pte_young(pte), > - "%s: racy access flag clearing: 0x%016llx -> 0x%016llx", > - __func__, pte_val(old_pte), pte_val(pte)); > - VM_WARN_ONCE(pte_write(old_pte) && !pte_dirty(pte), > - "%s: racy dirty state clearing: 0x%016llx -> 0x%016llx", > - __func__, pte_val(old_pte), pte_val(pte)); > - VM_WARN_ONCE(!pgattr_change_is_safe(pte_val(old_pte), pte_val(pte)), > - "%s: unsafe attribute change: 0x%016llx -> 0x%016llx", > - __func__, pte_val(old_pte), pte_val(pte)); > -} > +void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, pte_t pte); > That implies that any __set_ptes_anysz() will invoke another function call that will not be optimized out. You should likely keep most of __check_safe_pte_update() in the header as an inline function (or at least the CONFIG_DEBUG_VM check), and only move the "slow path" code. Alternatively, make the whole thing #ifdef CONFIG_DEBUG_VM and provide an empty inline helper for !CONFIG_DEBUG_VM. That's probably the cleanest, because performance with CONFIG_DEBUG_VM is not really relevant. -- Cheers, David