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Wed, 9 Feb 2022 18:59:23 +0000 Received: from BY5PR10MB4196.namprd10.prod.outlook.com ([fe80::11f6:860e:575a:e6f1]) by BY5PR10MB4196.namprd10.prod.outlook.com ([fe80::11f6:860e:575a:e6f1%5]) with mapi id 15.20.4951.021; Wed, 9 Feb 2022 18:59:23 +0000 Message-ID: Date: Wed, 9 Feb 2022 10:59:20 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v4 4/5] mm: hugetlb: fix missing cache flush in hugetlb_mcopy_atomic_pte() Content-Language: en-US To: Muchun Song , akpm@linux-foundation.org, zi.yan@cs.rutgers.edu, kirill.shutemov@linux.intel.com, rientjes@google.com, lars.persson@axis.com, ziy@nvidia.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, duanxiongchun@bytedance.com, fam.zheng@bytedance.com References: <20220208073617.70342-1-songmuchun@bytedance.com> <20220208073617.70342-5-songmuchun@bytedance.com> From: Mike Kravetz In-Reply-To: <20220208073617.70342-5-songmuchun@bytedance.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: CO1PR15CA0106.namprd15.prod.outlook.com (2603:10b6:101:21::26) To BY5PR10MB4196.namprd10.prod.outlook.com (2603:10b6:a03:20d::23) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: d40aaa40-6b74-4277-8a9f-08d9ebfe4941 X-MS-TrafficTypeDiagnostic: BYAPR10MB2885:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:4502; 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There are 2 ways to fix this issue. > > 1) insert flush_dcache_page() after folio_copy(). > 2) replace folio_copy() with copy_user_huge_page() which already > considers the cache maintenance. > > We chose 2) way to fix the issue since architectures can optimize this > situation. > > Fixes: 8cc5fcbb5be8 ("mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY") > Signed-off-by: Muchun Song > --- > mm/hugetlb.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) Thanks! This will also make backports easier. Reviewed-by: Mike Kravetz -- Mike Kravetz