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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?6qm3JodVIlce4SXirAVRnifCmujhfw81BD2Bni20jW+Od6kor7VWUW4P598k?= =?us-ascii?Q?YsdoIIMLVv7sX50uycZQ6N6CwnMdIV8VeAmI+QPlRxyZ1JzarHztfpjE+hwe?= =?us-ascii?Q?QWwkuIVohucHl8J5Qv+1bKot9465uRZR6OdCsBFGCGfqH2nR0Z5QVMHjepfe?= =?us-ascii?Q?owfAdTRQQ3HzzZkumypgzyAbb120Y/bIs0HKWidUHxaK2TYZDn8DCIzo2e3n?= =?us-ascii?Q?RNMtbakBdlZClJRAvvFJmzkXldhiP8KIJqWE4dq3lQg6NK50bSR0nH40b85a?= =?us-ascii?Q?iOQO97+/I4cpFcX6FGy80GkgUqtaO63aEpdGx1TMBu+TQYZ5SBZybsfabU6i?= =?us-ascii?Q?2Ofegb8uSDInvKTOYQNSLnjybFDtTNHuVzz8mGWWH6oMDXNnCKycAbgjalqX?= =?us-ascii?Q?fzhWPk3DMUj5L63YV5WbYS15/KniuBJKmk4WW8qU+kWydkWvTLPW31SCeA9j?= =?us-ascii?Q?vwumKHFigy86Ui6kYMj6ga9FiWYHtNxz6EwhVmhK/I+Si9FwD+bsD5Gy+Omz?= =?us-ascii?Q?0SJIyqXK66+OvQS20/EGqngPAHMVtGlnxhNsaA7cwR4Lpkfnkr4VCaHkqcdG?= =?us-ascii?Q?f2Mi7mLfYp1VPDc313ecN8cLkJoeG+KVyhyxCJ7NHbXN5XlSHeL0bx6m5f/D?= =?us-ascii?Q?W+Yl9edjL6JOoeH3k9EOggREYAGfamDLIGbQ8lQXJkfbY4bh5FQlbQyAfYCy?= =?us-ascii?Q?+zLsz7B+dj+qsb2oiqbpQSRZZG6efBAyr9q2mXykhPo0Pwr9nLtTCcPT0A9U?= =?us-ascii?Q?QRaftmmJ81l9Nab8LefAFJ3syUp/xr3qRh/jQ413vJjSg5BY8oi0bmQt8R9a?= =?us-ascii?Q?hK5bcO+rPfFq+KGj5LWmToRB2K6+nCix1tKiaJwHLyVKDli1B1qyRuVfoJtM?= =?us-ascii?Q?OGuNGr//rnbRSE6KKdewjiga3UzN968SkqTqr6Dgx1TqXdC6GZNX2GIbahZq?= =?us-ascii?Q?A8DvKWoYCOooNxL1O7epZFDgFj8J9DXNz3PPsBhQePHJtu8VAOOfHggW2LV5?= =?us-ascii?Q?81TnIP79hRjPAhjOnxHvxOoKX78iagY2sctARPtad2h+jFWpSQZ0acwEeHvD?= =?us-ascii?Q?8MPajaCOjRry95hOMmDpaA/xFbzGtQ/WYWTtvAiKH7VNtdSgBK4tdwPbvJLs?= =?us-ascii?Q?mqBO4LEU/+h1tbyWF6FQmsKyOuaJOr5ZKt0CtBqsAGDHcMujh7q6HOcsLEd3?= =?us-ascii?Q?VqZ+aqFvVBSVC4+A1tz3rTpIex/kjSL5nZiMMppvwURp2YgD38T+BKQJVmO4?= =?us-ascii?Q?6T+oSckrqJYK6jNjAkUkfuqRelGbs707SM3F1LDGhj1cDcQ3b6hTbXdDHPXA?= =?us-ascii?Q?kLA4BVwMcrLgmja+fvUMjE7WWpY5wBeVJzvO32paasPcWrTXIiCN+LhQiNH9?= =?us-ascii?Q?ehL96RmnSVy5CFNl9R3y4cj5z2wSjVd9Rw3N//7RnVL2A/b/rg2ORaZmhwhN?= =?us-ascii?Q?dfp0L+t3WCuDz2JuaIVoRPukI2O9eQth1jH/4T9OIEE7Db4d/AIi1mM5pIBY?= =?us-ascii?Q?QrYD2WgF9hsaVjfh1vbCQEpYKaSSEvzoJp9QHE3M718jBFH97wcYj+TVG4Fw?= =?us-ascii?Q?6wDwJfYCZKisjndkHws=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 14bed215-fca7-4223-0cc1-08daccb34b77 X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Nov 2022 17:59:26.4589 (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: fVAltAsuUAy4RBdkwDjTZWnwaGsMoZVFKAAA1+vtK8RcXqDPk3s0e71mHdyE8AZp X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB8018 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 22, 2022 at 09:41:07AM -0800, Mike Kravetz wrote: > On 11/22/22 10:05, David Hildenbrand wrote: > > On 21.11.22 22:33, Andrew Morton wrote: > > > On Mon, 21 Nov 2022 09:05:43 +0100 David Hildenbrand wrote: > > > > > > > > > MikeK do you have test cases? > > > > > > > > > > Sorry, I do not have any test cases. > > > > > > > > > > I can ask one of our product groups about their usage. But, that would > > > > > certainly not be a comprehensive view. > > > > > > > > With > > > > > > > > https://lkml.kernel.org/r/20221116102659.70287-1-david@redhat.com > > > > > > > > on it's way, the RDMA concern should be gone, hopefully. > > > > > > > > @Andrew, can you queue this one? Thanks. > > > > > > This is all a little tricky. > > > > > > It's not good that 6.0 and earlier permit unprivileged userspace to > > > trigger a WARN. But we cannot backport this fix into earlier kernels > > > because it requires the series "mm/gup: remove FOLL_FORCE usage from > > > drivers (reliable R/O long-term pinning)". > > > > > > Is it possible to come up with a fix for 6.1 and earlier which won't > > > break RDMA? > > > > Let's recap: > > Thanks! > > > > > (1) Nobody so far reported a RDMA regression, it was all pure > > speculation. The only report we saw was via ptrace when fuzzing > > syscalls. > > > > (2) To trigger it, one would need a hugetlb MAP_PRIVATE mappings without > > PROT_WRITE. For example: > > > > mmap(0, SIZE, PROT_READ, > > MAP_PRIVATE|MAP_ANON|MAP_HUGETLB|MAP_HUGE_2MB, -1, 0) > > or > > mmap(0, SIZE, PROT_READ, MAP_PRIVATE, hugetlbfd, 0) > > > > While that's certainly valid, it's not the common use case with > > hugetlb pages. > > FWIW, I did check with our product teams and they do not knowingly make use > of private mappings without write. Of course, that is only a small and > limited sample size. Yeah, if it is only this case I'm comfortable as well Jason