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Thu, 2 Sep 2021 23:23:48 +0000 Subject: Re: [patch 075/212] mm/gup: remove try_get_page(), call try_get_compound_head() directly To: Andrew Morton , borntraeger@de.ibm.com, gor@linux.ibm.com, hca@linux.ibm.com, hch@lst.de, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, willy@infradead.org References: <20210902215354.ipaXS8yYx%akpm@linux-foundation.org> From: John Hubbard Message-ID: Date: Thu, 2 Sep 2021 16:23:46 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 In-Reply-To: <20210902215354.ipaXS8yYx%akpm@linux-foundation.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SJ0PR05CA0193.namprd05.prod.outlook.com (2603:10b6:a03:330::18) To BY5PR12MB4130.namprd12.prod.outlook.com (2603:10b6:a03:20b::16) MIME-Version: 1.0 Received: from [10.2.52.41] (216.228.112.22) by SJ0PR05CA0193.namprd05.prod.outlook.com (2603:10b6:a03:330::18) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4500.7 via Frontend Transport; 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dkim=pass header.d=Nvidia.com header.s=selector2 header.b=uVJurzpN; dmarc=pass (policy=quarantine) header.from=nvidia.com; spf=none (imf25.hostedemail.com: domain of jhubbard@nvidia.com has no SPF policy when checking 40.107.236.70) smtp.mailfrom=jhubbard@nvidia.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 99F14B000184 X-Stat-Signature: q63pmbu9uyd8butdwddn73yj7wzw58ms X-HE-Tag: 1630625030-511846 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000435, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 9/2/21 2:53 PM, Andrew Morton wrote: ... > --- a/mm/gup.c~mm-gup-remove-try_get_page-call-try_get_compound_head-directly > +++ a/mm/gup.c > @@ -62,11 +62,24 @@ static void put_page_refs(struct page *p > put_page(page); > } > > -/* > - * Return the compound head page with ref appropriately incremented, > - * or NULL if that failed. > +/** > + * try_get_compound_head() - return the compound head page with refcount > + * appropriately incremented, or NULL if that failed. > + * > + * This handles potential refcount overflow correctly. It also works correclty s/correclty/correctly/ ...that is, if it is reasonable to do a typo fixup at this stage in the cycle. thanks, -- John Hubbard NVIDIA