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Wed, 31 Jul 2024 20:35:09 +0800 Message-ID: Date: Wed, 31 Jul 2024 20:35:08 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC v11 08/14] mm: page_frag: some minor refactoring before adding new API To: Alexander H Duyck CC: , , , , , Andrew Morton , References: <20240719093338.55117-1-linyunsheng@huawei.com> <20240719093338.55117-9-linyunsheng@huawei.com> <5a0e12c1-0e98-426a-ab4d-50de2b09f36f@huawei.com> Content-Language: en-US From: Yunsheng Lin In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.120.129] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemf200006.china.huawei.com (7.185.36.61) X-Stat-Signature: rwsnnzbjj15osjc7d9tubyureep3zz6w X-Rspamd-Queue-Id: 82BCA12001D X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1722429315-440095 X-HE-Meta: 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 ISnCNrFL UBQMWDTUkbUawVu96KpWDIbjcJ3bVVDXRxQmpTdoSIgtmNBlQu4ZAXVr7QetD+C4sV1mxj5/t6bY4Qui6TOcxBHUFheA/+4RsWJfEaX/xthuHjQXVKMsI4B7+188VoN2OmDQ6l2oHPtnY6YGpnpfQ205dzkYIHt3P/erCLnrCKBqEeCV5rSP9jFnSglYYRN3ow1HENlqF8lVBHfJU/z3GGkQPAaq2uzfmghu4I747pau6i7tA/7XUUwVITWlbff5ooD+MEG4gtpjHsUAU+oMyi7/+Si3018A2Fu8orfo8AIAQNdJA0+GMKSex0w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024/7/30 23:12, Alexander H Duyck wrote: ... >> } >> >> nc->pagecnt_bias--; >> nc->remaining = remaining - fragsz; >> >> return encoded_page_address(encoded_va) + >> (page_frag_cache_page_size(encoded_va) - remaining); > > Parenthesis here shouldn't be needed, addition and subtractions > operations can happen in any order with the result coming out the same. I am playing safe to avoid overflow here, as I am not sure if the allocator will give us the last page. For example, '0xfffffffffffff000 + 0x1000' will have a overflow.