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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 09GJuZODEEMwMRnIQnjXPHdrTfSvUR71iNBtNM6vTWgZHjT/ny9udG/OPwfCROGMeBoPKCG8MwEE365m391kVjKKTHtngp/6Zv3Q6vbfXz0AOWUApumq+mS6s3fjYS7Mr186Qrthzfv9w0VP5tOKQTy/eLRyhcqsS+cat/IbJIwXtu+3drq4ScYu+Le3gTa1SfnM7CfHM+7UZU0uYez5mMHpEj5SWGykX5JUoUyFNMVug8c9cG7Rtg1DgCcvFldcjvDp3iD1i9OldzHa6ZNYkCOvEI1PpvcAo9YmK1iMdS66vw4gu8KOR375qFDjA8HqsAKXaCk2wcqJUqMqe7ivHaYhbNNC1x7A4rIkBHuUoqzyTZ/YD8IWukG8P/3WMpEB/E1YlRJpIygpYuhbh0Izl9Tk7tAAh2VEn57AoCT6oc3WWJ4c0tVyNzYvPwpjutOY X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Apr 2026 23:26:34.3603 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b6976780-2417-46cb-9157-08dea70feb1f X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SA2PEPF00001508.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA3PR12MB9089 resctrl_kcfg.k_rdtgrp records which rdtgroup currently owns the kernel CLOSID/RMID, but nothing cleared that snapshot when the group was removed. rmdir of a control or monitor group, or unmount of the resctrl filesystem, left kernel mode enabled on the CPUs the group covered and left k_rdtgrp pointing at freed memory; the next read or write of info/kernel_mode would dereference a stale rdtgroup under rdtgroup_mutex. Add rdtgroup_config_kmode_delete() as the disable counterpart of rdtgroup_config_kmode(). It clears the kernel-mode binding on the group's kmode_cpu_mask (or all online CPUs when that mask is empty), drops the per-group kmode/kmode_cpu_mask bookkeeping, and if @rdtgrp was the bound, resets resctrl_kcfg to &rdtgroup_default, BIT(INHERIT_CTRL_AND_MON)) so subsequent sysfs operations resolve to a live group. Call it from rdtgroup_rmdir_mon(), rdtgroup_rmdir_ctrl(), and resctrl_fs_teardown(); each call site is gated on rdtgrp->kmode so groups that never participated in kernel mode pay nothing. Signed-off-by: Babu Moger --- v3: New patch to handle the kernel_mode clean up. --- fs/resctrl/rdtgroup.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c index 5383b4eb23ed..faf390893109 100644 --- a/fs/resctrl/rdtgroup.c +++ b/fs/resctrl/rdtgroup.c @@ -1194,6 +1194,40 @@ static int rdtgroup_config_kmode_clear(struct rdtgroup *rdtgrp, int kmode) return 0; } +/** + * rdtgroup_config_kmode_delete() - Drop @rdtgrp's kernel-mode binding + * @rdtgrp: Resctrl group whose kernel-mode binding is being removed (e.g. + * because the group is about to be rmdir'd or the filesystem is + * being torn down). No-op when %NULL or when @rdtgrp never + * carried a kernel-mode binding. + * + * Wraps rdtgroup_config_kmode_clear() to disable the hardware programming + * and reset the per-group bookkeeping. When @rdtgrp is the group currently + * bound in @resctrl_kcfg, the snapshot is also reset to + * (&rdtgroup_default, BIT(INHERIT_CTRL_AND_MON)) so subsequent show/write + * paths do not dereference @rdtgrp after the caller frees it. + * + * If the underlying tear-down fails (cpumask allocation), the snapshot is + * still reset because @rdtgrp is about to disappear; stale enable bits on + * those CPUs are reported via pr_warn() and will be cleared by the next + * non-INHERIT reprogram. + * + * Context: Caller must hold rdtgroup_mutex. + */ +static void rdtgroup_config_kmode_delete(struct rdtgroup *rdtgrp) +{ + if (!rdtgrp || !rdtgrp->kmode) + return; + + if (rdtgroup_config_kmode_clear(rdtgrp, resctrl_kcfg.kmode_cur)) + pr_warn("resctrl: kernel-mode disable failed; stale enable bits may persist\n"); + + if (resctrl_kcfg.k_rdtgrp == rdtgrp) { + resctrl_kcfg.k_rdtgrp = &rdtgroup_default; + resctrl_kcfg.kmode_cur = BIT(INHERIT_CTRL_AND_MON); + } +} + /** * rdtgroup_by_kmode_path() - Resolve a "//" path to an rdtgroup * @ctrl_name: Control-group name, or "" for the default control group. @@ -3635,6 +3669,7 @@ static void resctrl_fs_teardown(void) mon_put_kn_priv(); rdt_pseudo_lock_release(); rdtgroup_default.mode = RDT_MODE_SHAREABLE; + rdtgroup_config_kmode_delete(&rdtgroup_default); closid_exit(); schemata_list_destroy(); rdtgroup_destroy_root(); @@ -4432,6 +4467,8 @@ static int rdtgroup_rmdir_mon(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask) u32 closid, rmid; int cpu; + rdtgroup_config_kmode_delete(rdtgrp); + /* Give any tasks back to the parent group */ rdt_move_group_tasks(rdtgrp, prdtgrp, tmpmask); @@ -4482,6 +4519,8 @@ static int rdtgroup_rmdir_ctrl(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask) u32 closid, rmid; int cpu; + rdtgroup_config_kmode_delete(rdtgrp); + /* Give any tasks back to the default group */ rdt_move_group_tasks(rdtgrp, &rdtgroup_default, tmpmask); -- 2.43.0