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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774288551; bh=VbCHYIuEB3QD6Shd9lNFnvrZhPFSCzFNxS26OEzV4YQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=EH+kk9F4cET+6hBw+hfgT1O7mgwe2YVYpi8ON4Hlqv3UBhAP+D7aSImBMsunnA01j yXqborcZqNAgukb+/+AAioUQf9oJZXLqF5hly5DXoOzydpkwkZSqQ85B+tSp1xo7JT HYDKHEL95p8nIWwf6mEuq0/D+KciFk1I8OcDuoXSk4lC7gqvvYxeHgML63sAromxSY f2JqjC5lFuuzOgwPnO6R5Y8bHVGb/8KMbvUuq0JuIhtm6NDya0gZmeuFVD4dYBTF9y NmC57B/yOKTlM/7Rkzld0yyndRA4qk40CIOpFo0H+rpWeYk3SULQMJmL6A9sQ+jZjm bmQVJInFNb7FA== Message-ID: <0a14c10d-0dab-4b9c-85ec-e0ee25cd0db8@kernel.org> Date: Mon, 23 Mar 2026 18:55:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v11 05/16] mm/gup: drop local variable in gup_fast_folio_allowed To: "Kalyazin, Nikita" , "kvm@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.linux.dev" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "bpf@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "kernel@xen0n.name" , "linux-riscv@lists.infradead.org" , "linux-s390@vger.kernel.org" , "loongarch@lists.linux.dev" , "linux-pm@vger.kernel.org" Cc: "pbonzini@redhat.com" , "corbet@lwn.net" , "maz@kernel.org" , "oupton@kernel.org" , "joey.gouly@arm.com" , "suzuki.poulose@arm.com" , "yuzenghui@huawei.com" , "catalin.marinas@arm.com" , "will@kernel.org" , "seanjc@google.com" , "tglx@kernel.org" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "hpa@zytor.com" , "luto@kernel.org" , "peterz@infradead.org" , "willy@infradead.org" , "akpm@linux-foundation.org" , "lorenzo.stoakes@oracle.com" , "vbabka@kernel.org" , "rppt@kernel.org" , "surenb@google.com" , "mhocko@suse.com" , "ast@kernel.org" , "daniel@iogearbox.net" , "andrii@kernel.org" , "martin.lau@linux.dev" , "eddyz87@gmail.com" , "song@kernel.org" , "yonghong.song@linux.dev" , "john.fastabend@gmail.com" , "kpsingh@kernel.org" , "sdf@fomichev.me" , "haoluo@google.com" , "jolsa@kernel.org" , "jgg@ziepe.ca" , "jhubbard@nvidia.com" , "peterx@redhat.com" , "jannh@google.com" , "pfalcato@suse.de" , "skhan@linuxfoundation.org" , "riel@surriel.com" , "ryan.roberts@arm.com" , "jgross@suse.com" , "yu-cheng.yu@intel.com" , "kas@kernel.org" , "coxu@redhat.com" , "kevin.brodsky@arm.com" , "ackerleytng@google.com" , "yosry@kernel.org" , "ajones@ventanamicro.com" , "maobibo@loongson.cn" , "tabba@google.com" , "prsampat@amd.com" , "wu.fei9@sanechips.com.cn" , "mlevitsk@redhat.com" , "jmattson@google.com" , "jthoughton@google.com" , "agordeev@linux.ibm.com" , "alex@ghiti.fr" , "aou@eecs.berkeley.edu" , "borntraeger@linux.ibm.com" , "chenhuacai@kernel.org" , "dev.jain@arm.com" , "gor@linux.ibm.com" , "hca@linux.ibm.com" , "palmer@dabbelt.com" , "pjw@kernel.org" , "shijie@os.amperecomputing.com" , "svens@linux.ibm.com" , "thuth@redhat.com" , "wyihan@google.com" , "yang@os.amperecomputing.com" , "Jonathan.Cameron@huawei.com" , "Liam.Howlett@oracle.com" , "urezki@gmail.com" , "zhengqi.arch@bytedance.com" , "gerald.schaefer@linux.ibm.com" , "jiayuan.chen@shopee.com" , "lenb@kernel.org" , "osalvador@suse.de" , "pavel@kernel.org" , "rafael@kernel.org" , "vannapurve@google.com" , "jackmanb@google.com" , "aneesh.kumar@kernel.org" , "patrick.roy@linux.dev" , "Thomson, Jack" , "Itazuri, Takahiro" , "Manwaring, Derek" References: <20260317141031.514-1-kalyazin@amazon.com> <20260317141031.514-6-kalyazin@amazon.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: <20260317141031.514-6-kalyazin@amazon.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 8yqzsej6wkihypr6nhwgi85xz4ri5888 X-Rspamd-Queue-Id: 4BADD180004 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1774288552-815504 X-HE-Meta: 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 MJ6EBmOh nqzodX9/rohXl3lYhnx/lmKfcCXASYvVmcS6TtSCAqfXmnuOTkcZEbC3ycBwLDLitzp39JCaENreyNLXXrJMFXWRHZkTvCvS8FqjCE0cMSMAOeynVehZ59G8w8FopmFeZG3th69BiWogqeZXFHFwmYuYoYGuqQ/nSvLMXcp9jSKYS2uHw8ILTbQzGVQ5ZsS4SXDAEFLNjvoiugAio9wyqetALkmU2YxhJspo34BZdpSBXabRRtSQZREiy9fD/vdF5+TpGgQrdjiIEc4DPE0l94JRpKJAU3HVXRVk6G9fdfUs3yyhUsrNnNRG3GgSJapKkffQggRJ9Sj3T3H4bPl2jp7Tx4SnkPPj/snFbJuv1x2ltkqr4viRHZRrw7a70wRJTZ2cG+8zBKD5kzn7MwFPiyvr0N5Paq99GPmr+hC0Ys9TPebc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/17/26 15:11, Kalyazin, Nikita wrote: > From: Nikita Kalyazin > > Move the check for pinning closer to where the result is used. > No functional changes. > > Signed-off-by: Nikita Kalyazin > --- > mm/gup.c | 23 ++++++++++++----------- > 1 file changed, 12 insertions(+), 11 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 5856d35be385..869d79c8daa4 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -2737,18 +2737,9 @@ EXPORT_SYMBOL(get_user_pages_unlocked); > */ > static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags) > { > - bool reject_file_backed = false; > struct address_space *mapping; > unsigned long mapping_flags; > > - /* > - * If we aren't pinning then no problematic write can occur. A long term > - * pin is the most egregious case so this is the one we disallow. > - */ > - if ((flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) == > - (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) > - reject_file_backed = true; > - > /* We hold a folio reference, so we can safely access folio fields. */ > if (WARN_ON_ONCE(folio_test_slab(folio))) > return false; > @@ -2793,8 +2784,18 @@ static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags) > */ > if (secretmem_mapping(mapping)) > return false; > - /* The only remaining allowed file system is shmem. */ > - return !reject_file_backed || shmem_mapping(mapping); > + > + /* > + * If we aren't pinning then no problematic write can occur. A writable > + * long term pin is the most egregious case, so this is the one we > + * allow only for ... > + */ > + if ((flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) != > + (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) > + return true; > + > + /* ... hugetlb (which we allowed above already) and shared memory. */ > + return shmem_mapping(mapping); Acked-by: David Hildenbrand (Arm) I'm wondering if it would be a good idea to check for a hugetlb mapping here instead of having the folio_test_hugetlb() check above. Something to ponder about :) -- Cheers, David