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Shutemov" , kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, yu.c.zhang@linux.intel.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, david@redhat.com, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com Subject: Re: [PATCH v3 04/11] KVM: guest_memfd: Allow host to mmap guest_memfd() pages when shared Message-ID: <20241010143716.GC3394334@nvidia.com> References: <20241010085930.1546800-1-tabba@google.com> <20241010085930.1546800-5-tabba@google.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?08mQIMKBvOEB5BXranZeXYkkQ84cO8p0DJPqw9G+oAwDdeKgqkPBWoRC/q4p?= =?us-ascii?Q?jXJMU2wOcIBUzOH4oZDDVOA0X0DP7JBAwVzrWr/ogIC/43FcbLHnvS897Odl?= =?us-ascii?Q?YXoIw5eoLDluC0HVlTyQqyz6Ze4YeHkQR3U1nAihUxI4V58S0oDxslj6bXN7?= =?us-ascii?Q?f2EbT2OnRCIRcODEet15Yj87sfJ/NkdWw37O4+AxXonsFOZaYuHQf5kzq8bu?= =?us-ascii?Q?w9AH35NRiMxYI533cZcEl3CMY8uINyPb9Z7mYYmRQ+QhH1OrEsCdV5Qr3G1a?= =?us-ascii?Q?ssULgH/SMTmWJ23Ne3smkrGZO9m/LF86OmWxwneoLaLMkVw8c7GIe6Rjm55D?= =?us-ascii?Q?mxeZ0PYRcEDAn1Ss3Erek+qzUCKh0maa+L1jcPNA81Ili7e5xHsfUvwAAm39?= =?us-ascii?Q?bM6k1lfcXXySIZnI91GPVnl+x9Dwn+Uz+XhtiT3gAScEsRxdUGeKgonDa3Ry?= =?us-ascii?Q?n1Nhfx3csAZK4AW/USNmTt+yhm2AM49RecYEORgq/ZieduSxOYIoFfu5wCe7?= =?us-ascii?Q?rSUEKEa/GjXZPgDcBrJwVh5Wv1SPRrCE4rmm73q1WYQnyze1jluK4m6PJrFS?= =?us-ascii?Q?UdlOYq4Vh5KTYup5haucMEBrq7FkUeiZCLgZQENf4uxRnVKGCMruforMeZbv?= =?us-ascii?Q?dQjz2lkWejQhVqXaG10IGcB/xos1FWsxq1zvpP/jG26Up42qSy+Cl3kpt905?= =?us-ascii?Q?JBGxIuV7TqGL4rLZNaxgSm8R8gsPcpkxIV75jUVdpzRKN7MGQK41+1oox5/w?= =?us-ascii?Q?h7rrAtVAU7dJrg+EKUMCfDPglFzgQQdVV9dg7Nxz1sZjqEHClWxwSwSeZTCq?= =?us-ascii?Q?/KVs4LsYm+r/+EZFlWv92xam+Dt9ApaA9jYHQ0FZnqYZzSZt/YQ9PkOSouNU?= =?us-ascii?Q?IFj/lsXC0LKgXz46ONOlet08oVAmn9L5DPgIaR/WJ5h0K6KLtKKwgDMVcBMp?= =?us-ascii?Q?sMGEQLiNM/w7x3xqRm76P9TV/WjH2b+9CnSMycFXWXcLWbSBPaw4BOicMndx?= =?us-ascii?Q?A7OY6z23joImlVPmeuGD+xwBQAnCMh0Jr3YIWpjFKNbYQLqUuJT1LREjPQ55?= =?us-ascii?Q?BUAwiIg3mxMqmeIisSsdxHuPY6bqA/b7mb+nTxgkQPHMTwBwDolEv5GHz4fw?= =?us-ascii?Q?YdkKVPKF7k+C4d+oiVL6zO+7nzUILsjHrLEd1Crg2nIs6sJ/EDy0Amb5fs51?= =?us-ascii?Q?0MwaWw9YBJpeDvPTKFMNXkARY3TTdQVKR/5div3uLp/6D7ImslnU5xylsFqL?= =?us-ascii?Q?RdT9s8dsjJNGpPv7NOxhNusCxbDeOT4Q3Ix1+skXcADT+ecEG6AmCunfhvO3?= =?us-ascii?Q?JT4FKuhO6H5jXQaA+nklMm3KUrTLIFnlFXxXNGya292iW1oG3Wd0G5XLWEQ8?= =?us-ascii?Q?C8iRvnFu9XhZs/XKjbadknboFmOJG3IK30YRvd3kC7kxti7IzkxBe+NnpGsZ?= =?us-ascii?Q?dl0pwqGMjpFMegAVy1xBM2Q2gRQZ8sdNvLjk9AdxwrTrsoqdAk3T8Xn6Fs/J?= =?us-ascii?Q?DMvAOADeNduR/E3Bbex0F2EFDfHgyrxbrMKv/fDwGt8Pfj5IsZkKUmTFx9Va?= =?us-ascii?Q?lfeh0YVp7l/2Xna5Tvs=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 01fa6988-38c3-4e25-ca12-08dce9390a0f X-MS-Exchange-CrossTenant-AuthSource: CH3PR12MB8659.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Oct 2024 14:37:17.2494 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: YJL1Lhm14K4bkrayh+TfAYPYgVB3CnD8iVQUAByuncA1bRCsRfdUTafie098v/Fi X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB8558 On Thu, Oct 10, 2024 at 03:28:38PM +0100, Fuad Tabba wrote: > I remember discussing this before. One question that I have is, is it > possible to get a transient pin while the folio lock is held, No, you can't lock a folio until you refcount it. That is a basic requirement for any transient pin. Jason