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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?I+dvYNPrbTt+rKoBOA3IdbsdywxGhTz94pNAMirkOTkFX71JO1zCp+gNPX4v?= =?us-ascii?Q?RHcLU56xcANvvvwVclE4JOGaD4Ys1ct01Rw11FBXrmM/YasHK8lw4Thiz8a0?= =?us-ascii?Q?JVJLLnIvJK13kuG7VH8v2HaANWXn4hnCR2SxMXDkAt2rcVtk2bLGO/3YpCEG?= =?us-ascii?Q?JpsRN5L+zF2O1CS9eB9birTfXPeU9txWzliSE91mx6zIsxpncmQeblCe8mWW?= =?us-ascii?Q?qm3FRdBRSB0W9dwijTHNxiliyJbX6XwRkTpKzi37OOtUhScQdCMqJx1uvybX?= =?us-ascii?Q?w133RvgKnQP1dn4Q60yfV+ig1tQb84GFNu4Gt5/91/5b/7h++6YWDorxm8x1?= =?us-ascii?Q?BY2r8hn3PDRYXDI7VzHASBSbQKuV942Yxm9OapyglwByJ9vYDk0xVRuxHeda?= =?us-ascii?Q?LVow+8xop533GT06MpXhrlZ7ffQ1ntA8njtzSiGzQDp5bXs6WooJDqI/hQtT?= =?us-ascii?Q?tDMBnu0x5/wiFy9Hty8PXYF8v0hGPxuQ2iKdY4AaTcK54NHiVCxOJuonjZeU?= =?us-ascii?Q?WBKqtdfLkC0ouMX4+fEq5uFgopfvnsHB+2hOYN/LRa+aaz1OnAKBzI20/Fus?= =?us-ascii?Q?4WYDba7FIbDnLc1Pq7IDmeczFfQoceigDwrF7+7iDJxoPH8iHfKCv0z1VcXr?= =?us-ascii?Q?5jr/db5EjCVaITjuZqSj2XKM9VOCVNY3HJFAtdQFtlHt/7EvzutO5USPw43k?= =?us-ascii?Q?rnltrA4ft7fVjccz3xy10FETD2Wbfr8XLF8Q+iDkNSY0P/QCu34zSW08FgZH?= =?us-ascii?Q?AjRfzsWyzichZRfZ8p3KnlkItwx4MtIXSl4gHqcpowyDGjA9BhTj7zk1Bs1s?= =?us-ascii?Q?NW3iIvsGG7i950ZUNujw7/kYLv91Hn6zORqXJxTQJtCf+97UkeNAgaJhUjG2?= =?us-ascii?Q?YUL4Q1BsCgX93PsVMG5UKlXVT3FNzIzmMGPItDAOEXReak8PHTdzz/Rlslyb?= =?us-ascii?Q?bY38cvWPIE5UNLvESXFXSuccqAbq3j2pohvEZZO5N8Z0RNxuVPX9z1vdZZUS?= =?us-ascii?Q?9USD+6dE/ppnfckSfx7ZK3qS5FfEPLcViXhuRXDI89N+5cMpCPrMz7M1YZPj?= =?us-ascii?Q?bfwPFC7vBtG/x4nVdYDTvqDPWAXz+M9WNsBZmjENKX8ZsZ551ngjB/YeFCw6?= =?us-ascii?Q?+IfLjk3175BDZnmanvcpHJ7W2MJHsTOjc8nz652gGJVkuCUfWSr4bLmlLtUF?= =?us-ascii?Q?E0ofCdUYuDRHb4uE+Wfqyt/5kVzXCVGGQ2mjuAYxARON3qKXog3RPIPWF0xd?= =?us-ascii?Q?bCAbPwjP99bp64T/ARSy4Az2r+ZeGpyR3cEom6dEO8F3x+MmHfSavKGNbCm1?= =?us-ascii?Q?xBcSbHQ4UOKoAeWqgXvOOAQZLNAhQy66FaK5lr+IPaFDfFPhFUyXGB00nT1M?= =?us-ascii?Q?xm4QmOyJKuz+mE+pCKdg9m1eG5F+khuJn6EXlxb0tEKWYIWoiq0ViMGSnxGX?= =?us-ascii?Q?J+ZCX/EllUVSedzSRxQHYkP7y6YnAzRIivebjv/5oXIdP0EqpEt+i42XQTuo?= =?us-ascii?Q?bX7EfuJUb5ESkCla+stOFPA2QmJX8rpbQtHbsGvhWoQXneiEX21iDZMX0jQ+?= =?us-ascii?Q?aRw9YIJOihZyUDOBtH3scufoN+HKI1MVchAkex31aA+wo9iXso9nfAda5qYh?= =?us-ascii?Q?cQ=3D=3D?= X-OriginatorOrg: memverge.com X-MS-Exchange-CrossTenant-Network-Message-Id: 83d28071-b802-446d-17dc-08daffcfc154 X-MS-Exchange-CrossTenant-AuthSource: BN6PR17MB3121.namprd17.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Jan 2023 19:01:39.5360 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 5c90cb59-37e7-4c81-9c07-00473d5fb682 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: bfTB7YSsgtAnCHNGXiaeog28k1/eBwpYo9R9dEiHNH+tTFtlVvNKu/YCyIswoIANVESBWAwjlKrWzOmq5wksQaqhPMRd6u/ElbXLpd4/k8Y= X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR17MB6646 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 26, 2023 at 10:53:49AM -0800, Andrei Vagin wrote: > On Thu, Jan 26, 2023 at 10:30 AM Oleg Nesterov wrote: > > > > On 01/26, Andrei Vagin wrote: > > > > > > On Thu, Jan 26, 2023 at 7:07 AM Oleg Nesterov wrote: > > > > > > > > IIUC, PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH is needed to run the injected > > > > code, and this also needs to change the state of the traced process. If > > > > the tracer (CRIU) dies while the tracee runs this code, I guess the tracee > > > > will have other problems? > > > > > > Our injected code can reheal itself if something goes wrong. The hack > > > here is that we inject > > > the code with a signal frame and it calls rt_segreturn to resume the process. > > > > What will happen if CRIU dies and clears ->ptrace right before > > syscall_user_dispatch() checks PT_SUSPEND_SYSCALL_USER_DISPATCH ? > > > > How the tracee will react to SIGSYS with unexpected .si_syscall ? > > I got it. PTRACE_O_SUSPEND_SUD doesn't help us here, because we rely > on sigreturn > that is called after ptrace_detach. Thanks. > > > > > > I don't expect that > > > the syscall user dispatch > > > is used by many applications, > > > > Agreed, so the case when CRIU will need to do the additional > > PTRACE_SET_SYSCALL_USER_DISPATCH_CONFIG twice to disable and then re-enable > > syscall_user_dispatch is unlikely. > > > > > so I don't strongly insist on > > > PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH. > > > > I too won't argue too much. but so far I do not feel there is enough > > justification for this feature ... > > Agree > > > > > Oleg. > > Seems that's consensus, I will drop it.