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Tue, 22 Sep 2026 11:53:55 +0000 Date: Tue, 22 Sep 2026 19:53:12 +0800 From: Yan Zhao To: Sean Christopherson CC: Paolo Bonzini , David Hildenbrand , , , Stefan Teodorescu , Dennis Tighe , Sashiko Bot , Ackerley Tng Subject: Re: [PATCH v5 6/6] KVM: guest_memfd: Drop superfluous WRITE_ONCE() when binding a memslot Message-ID: Reply-To: Yan Zhao References: <20260922001332.1121266-1-seanjc@google.com> <20260922001332.1121266-7-seanjc@google.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260922001332.1121266-7-seanjc@google.com> X-ClientProxiedBy: TYCP286CA0352.JPNP286.PROD.OUTLOOK.COM (2603:1096:405:7c::19) To DSVPR11MB9579.namprd11.prod.outlook.com (2603:10b6:8:383::17) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DSVPR11MB9579:EE_|SA1PR11MB6568:EE_ X-MS-Office365-Filtering-Correlation-Id: 074bb5bc-538a-4918-728e-08df18a02daf X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|376014|1800799024|366016|10067099003|56012099006|6133799003|22082099003|18002099003|4143699003|5023799004|11063799006; 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Because the memslot > * is not visible yet, kvm_gmem_get_pfn() is guaranteed to see the file. > */ > - WRITE_ONCE(slot->gmem.file, file); > + slot->gmem.file = file; > slot->gmem.pgoff = offset >> PAGE_SHIFT; > if (kvm_gmem_supports_mmap(inode)) > slot->flags |= KVM_MEMSLOT_GMEM_ONLY; > Thanks for the fix. Reviewed-by: Yan Zhao BTW: some questions regarding read/write to slot->gmem.file: The WRITE_ONCE() in kvm_gmem_unbind() and kvm_gmem_release() are also invoked when the memslot is inactive and unreachable -- are they also superfluous? Do we need the READ_ONCE() in __kvm_gmem_get_pfn(), considering that other slot fields (e.g., slot->gmem.pgoff) are read without READ_ONCE()?