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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?Q5w1A7PrBQKikQRrOk42lM7BwmvGiwbgZ6Blwf2EkjXEsYH4bQTWus1ThoPw?= =?us-ascii?Q?rPA25RrEpp3rkCFLtXYZJ0l5uvK96AuoHQeRRZ917ShqygkHrp/P5u7kL0nl?= =?us-ascii?Q?GDIn+7wYMcpPMusFx4bWe/UbvHXf0E4GRPbz4N3IVamUsuYxSUrgnd9zDUbC?= =?us-ascii?Q?ECCmp8DJvkFbX8VNCYu7lttLvSgsbICdoaCZ87OnOOSXbeC1Ph65/nTOPGXm?= =?us-ascii?Q?z3fYhoqD3k3MhkKy2FXM5faER7/uCI2b0mzdEa1fs+GPD6YVL0zp+uXR58eV?= =?us-ascii?Q?mTkDoIJgkAmNg1yjJtt6vzmTQHu12I9uuzAu08fDss29MWohXunexOsJU6Bs?= =?us-ascii?Q?TMnniUnbwnaYfpZRC3lCDjQqJKIqA9Gh31ReQywB+klxry328drM/Mlg7CUL?= =?us-ascii?Q?N825fOPMQFegh6KdiutsE7n2X62a0AVdb9LHwjHy/EgxpGywgDlvsfVjLY6R?= =?us-ascii?Q?MIHNgT1UKe5BlAunYKlleL9I8pbkwObxXpZOPPtNkosX9gmhPvjhO11TLMvG?= =?us-ascii?Q?6wemqmLOJ/+/sl1pBEeJO0hrMwkUUrnAxqfrrjPficsIucD0LejO0drFtXrJ?= =?us-ascii?Q?YKFNI/rbSf9r5EwSK8L/f/bKaYo5/8UfJi6zkhtHjLftKWn9XYBE+lKq/SpY?= =?us-ascii?Q?UNNFeh9zP6AvI4Jx7WeB8zxKN8MnqCWIJEdhhUR7rp8q4Wvb25oT5UJZg5qi?= =?us-ascii?Q?lW8vtCu/hxnmqRXCUXMm0HBo/2exM/3B3kB22h75VfNyrkA9DVxk9lHdTXl2?= =?us-ascii?Q?3zfJOETGgSnf9VgtZFrsnTq0tMmsq74hEDOYBmGWmCz5UAYgI+P8ez8Gub8f?= =?us-ascii?Q?WBLVgi5DnfAq7NZZKlEDKhxGs+677+RPxRpeXkfImxabABjpToa0aJdyxUVa?= =?us-ascii?Q?5tR9SivzxsAejYj9jT8VEiOCdsUeWm1xoBho2GDYACnEaUnDNmX9si+MoA/k?= =?us-ascii?Q?GgzkWj6MuueZlYB4QVIii/uR+meINtYm1qDXm+QjfD11c7MVnBxbh+pcuZ/q?= =?us-ascii?Q?kZ9QzZE056Jye1Rl7mIao1LsyE+tON9q6aGuRp2kuny8nAcXDvWlKGGIb0gu?= =?us-ascii?Q?nDcxhAwsHuXW9V/VT8Cf3PFlHRY37MDu6ftfulcpkj96OYRt7TZnGM4bNqHX?= =?us-ascii?Q?05rq1gH8NKIbDPtHUaE+iGxe54ADnsD82W3VCe9s5Jpwg1mmYeLPWs+gz/kc?= =?us-ascii?Q?hiN+g2c0HKUvl9yp14wGSo5i7KHG5Nvtyv68o191kSjVZhhdWfSmcEMuLGm4?= =?us-ascii?Q?BSYaHm8ToWj+9y7yQVZ3Dvqf8zP3WW9xV3BjOch+MK8Fy6NokBnzfFIUOJOh?= =?us-ascii?Q?SO4kITZhO3ZpfU1ZiaPI0ieBfjP5/Mbmx5CJHSe5JFqs0c6u9N0wz/IQt4Qm?= =?us-ascii?Q?BiTc436cTIO9EC5x4MY3lqETWhmfdXCjyyChfDF9Ai8p0pBK9NS2yjSWhzhw?= =?us-ascii?Q?uz3P9YxJ3fBaLN8wH4jP6rbY6pQEdnflwz2A7YNwqwtXvxdD46Oiwb3pNRrA?= =?us-ascii?Q?CJKQe8FX1NLBKEADUCOSgk7MzgeErMADxHmgitOqhqHRbKA1vlm7l2/vsjD2?= =?us-ascii?Q?b+Jt5wBjJeHTw6piqtEI2LNefCms5Dzl9lu3t8gXHR8Rjb60n6DXrl/2nocB?= =?us-ascii?Q?iLcbWrormDPIxLr++kPibAACd518MMT9o4QNaSVkSdZ0nTPkC7rLF0ADdd3f?= =?us-ascii?Q?2ext/wXtXzBTejiKxAda9jKozerDI9BmN/C8AW9aegQPEbju?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 95c6c8bb-4834-4787-819a-08df361407ef X-MS-Exchange-CrossTenant-AuthSource: BL1PR12MB5174.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Oct 2026 23:26:17.1949 (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: WfupOfaXwUp0J/pWg4dveYjIMLE995o9czCePQx63SvIuks+eF5JTeKUBOsUNGa+m895h8uqANA8ZZKbgaKIRA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB6602 On Thu, Oct 29, 2026 at 12:28:59PM -1000, Tejun Heo wrote: > The parent's ops.sub_attach() runs before the enable work checks that the > cgroup is still online, so the parent can get an attach for a cgroup whose > rmdir already returned. That complicates parents where cgroup cleanup and > sub-scheduler attach race. > > Check CSS_ONLINE and call ops.sub_attach() under cgroup_lock(), so that the > parent sees an attach only for a cgroup that is online. > > Fixes: ebeca1f930ea ("sched_ext: Introduce cgroup sub-sched support") > Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi Thanks, -Andrea > --- > kernel/sched/ext/internal.h | 4 ++++ > kernel/sched/ext/sub.c | 13 +++++++++++++ > 2 files changed, 17 insertions(+) > > diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h > index ff0a3d508533..58652370da5a 100644 > --- a/kernel/sched/ext/internal.h > +++ b/kernel/sched/ext/internal.h > @@ -869,6 +869,10 @@ struct sched_ext_ops { > * @sub_attach: Attach a sub-scheduler > * @args: argument container, see the struct definition > * > + * The sub-scheduler's cgroup is online for the whole call. If it goes > + * offline after the sub-scheduler is accepted, ops.sub_detach() > + * follows. > + * > * Return 0 to accept the sub-scheduler. -errno to reject. > */ > s32 (*sub_attach)(struct scx_sub_attach_args *args); > diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c > index b5d92d89629b..6bc6b93ca63a 100644 > --- a/kernel/sched/ext/sub.c > +++ b/kernel/sched/ext/sub.c > @@ -2340,8 +2340,21 @@ void scx_sub_enable_workfn(struct kthread_work *work) > .cgroup_path = sch->cgrp_path, > }; > > + /* > + * The cgroup stays online across ops.sub_attach(), so the parent never > + * sees an attach for a cgroup that rmdir already removed. > + */ > + cgroup_lock(); > + if (!(cgrp->self.flags & CSS_ONLINE)) { > + cgroup_unlock(); > + scx_error(sch, "cgroup is not online"); > + ret = -ENODEV; > + goto err_disable; > + } > ret = SCX_CALL_OP_RET(parent, sub_attach, NULL, > &sub_attach_args); > + cgroup_unlock(); > + > if (ret) { > ret = scx_ops_sanitize_err(sch, "sub_attach", ret); > scx_error(sch, "parent rejected (%d)", ret); > -- > 2.56.0 >