| Seq | Timestamp | Type | Name | Duration |
|---|---|---|---|---|
| 0/0 | 2026/08/25 03:33 | flow | patch-triage |
2mArgs:null Results: {
"EnableConfigs": [
"SCHED_CLASS_EXT",
"CGROUP_SCHED"
],
"FocusSymbols": [
"scx_tg_online",
"scx_group_set_idle"
],
"KMSANReasoning": "The patch renames `idle` to `sched_idle` in `struct scx_task_group` and adds `sched_idle` to `struct scx_cgroup_init_args`. It initializes this new field in several places using designated initializers (e.g., `struct scx_cgroup_init_args args = { ... }`). In C, designated initializers zero out any uninitialized fields and padding bytes. Furthermore, `struct scx_cgroup_init_args` is passed to a BPF program (kernel space), not directly copied to user space. There is no risk of uninitialized memory use or info-leaks introduced by this patch. Standard KASAN and other bug detectors are sufficient to catch any potential memory corruption or out-of-bounds accesses.",
"NeedsKMSAN": false,
"Reasoning": "The patch modifies the sched_ext subsystem to pass the `sched_idle` state of a cgroup to the BPF scheduler during cgroup initialization (`ops.cgroup_init()`). This is a functional change that exposes new data to BPF programs and is reachable via cgroup creation and `cpu.idle` modification while a sched_ext scheduler is active.",
"WorthFuzzing": true
} |
| 1/1 | 2026/08/25 03:33 | action | read-patch-diff |
0mArgs:null Results: {
"PatchDiff": "commit 3673dd47de278af3efbec49c7cbc842d047d7302\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Tue Aug 25 03:33:09 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h\nindex 582d7cd4a9839..7b9cdb65deef6 100644\n--- a/include/linux/sched/ext.h\n+++ b/include/linux/sched/ext.h\n@@ -323,7 +323,7 @@ struct scx_task_group {\n \tu64\t\t\tbw_period_us;\n \tu64\t\t\tbw_quota_us;\n \tu64\t\t\tbw_burst_us;\n-\tbool\t\t\tidle;\n+\tbool\t\t\tsched_idle;\n #endif\n };\n \ndiff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c\nindex c539d15cda637..4a9c382970935 100644\n--- a/kernel/sched/ext/ext.c\n+++ b/kernel/sched/ext/ext.c\n@@ -4682,7 +4682,7 @@ void scx_tg_init(struct task_group *tg)\n \ttg-\u003escx.weight = CGROUP_WEIGHT_DFL;\n \ttg-\u003escx.bw_period_us = default_bw_period_us();\n \ttg-\u003escx.bw_quota_us = RUNTIME_INF;\n-\ttg-\u003escx.idle = false;\n+\ttg-\u003escx.sched_idle = false;\n }\n \n /**\n@@ -4764,7 +4764,8 @@ int scx_tg_online(struct task_group *tg)\n \t\t\t\t{ .weight = tg-\u003escx.weight,\n \t\t\t\t .bw_period_us = tg-\u003escx.bw_period_us,\n \t\t\t\t .bw_quota_us = tg-\u003escx.bw_quota_us,\n-\t\t\t\t .bw_burst_us = tg-\u003escx.bw_burst_us };\n+\t\t\t\t .bw_burst_us = tg-\u003escx.bw_burst_us,\n+\t\t\t\t .sched_idle = tg-\u003escx.sched_idle };\n \n \t\t\tret = SCX_CALL_OP_RET(sch, cgroup_init,\n \t\t\t\t\t NULL, tg-\u003ecss.cgroup, \u0026args);\n@@ -4934,7 +4935,7 @@ void scx_group_set_idle(struct task_group *tg, bool idle)\n \t\tSCX_CALL_OP(sch, cgroup_set_idle, NULL, tg_cgrp(tg), idle);\n \n \t/* Update the task group's idle state */\n-\ttg-\u003escx.idle = idle;\n+\ttg-\u003escx.sched_idle = idle;\n \n \tpercpu_up_read(\u0026scx_cgroup_ops_rwsem);\n }\n@@ -5185,6 +5186,7 @@ static int scx_cgroup_init(struct scx_sched *sch)\n \t\t\t\t.bw_period_us = tg-\u003escx.bw_period_us,\n \t\t\t\t.bw_quota_us = tg-\u003escx.bw_quota_us,\n \t\t\t\t.bw_burst_us = tg-\u003escx.bw_burst_us,\n+\t\t\t\t.sched_idle = tg-\u003escx.sched_idle,\n \t\t\t};\n \n \t\t\tret = SCX_CALL_OP_RET(sch, cgroup_init, NULL, css-\u003ecgroup, \u0026args);\ndiff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h\nindex 53e136a47924d..c6987a3a073bf 100644\n--- a/kernel/sched/ext/internal.h\n+++ b/kernel/sched/ext/internal.h\n@@ -259,6 +259,9 @@ struct scx_cgroup_init_args {\n \tu64\t\t\tbw_period_us;\n \tu64\t\t\tbw_quota_us;\n \tu64\t\t\tbw_burst_us;\n+\n+\t/* whether the cgroup is configured SCHED_IDLE via cpu.idle */\n+\tbool\t\t\tsched_idle;\n };\n \n enum scx_cpu_preempt_reason {\ndiff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c\nindex 0554448835bd0..a17d84db93bdd 100644\n--- a/kernel/sched/ext/sub.c\n+++ b/kernel/sched/ext/sub.c\n@@ -1361,6 +1361,7 @@ static s32 scx_cgroup_claim_subtree(struct scx_sched *sch)\n \t\t\t.bw_period_us = tg-\u003escx.bw_period_us,\n \t\t\t.bw_quota_us = tg-\u003escx.bw_quota_us,\n \t\t\t.bw_burst_us = tg-\u003escx.bw_burst_us,\n+\t\t\t.sched_idle = tg-\u003escx.sched_idle,\n \t\t};\n \n \t\tif (tg-\u003escx.sched != parent ||\n@@ -1464,6 +1465,7 @@ static void scx_cgroup_return_subtree(struct scx_sched *sch)\n \t\t\t.bw_period_us = tg-\u003escx.bw_period_us,\n \t\t\t.bw_quota_us = tg-\u003escx.bw_quota_us,\n \t\t\t.bw_burst_us = tg-\u003escx.bw_burst_us,\n+\t\t\t.sched_idle = tg-\u003escx.sched_idle,\n \t\t};\n \n \t\t/* the first pass must have transferred everything */\n"
} |
| 2/1 | 2026/08/25 03:33 | agent | patch-evaluator |
1mModel:best-expensive Args: null Results: {
"EnableConfigs": [
"SCHED_CLASS_EXT",
"CGROUP_SCHED"
],
"FocusSymbols": [
"scx_tg_online",
"scx_group_set_idle"
],
"Reasoning": "The patch modifies the sched_ext subsystem to pass the `sched_idle` state of a cgroup to the BPF scheduler during cgroup initialization (`ops.cgroup_init()`). This is a functional change that exposes new data to BPF programs and is reachable via cgroup creation and `cpu.idle` modification while a sched_ext scheduler is active.",
"WorthFuzzing": true
}Instruction: You are an expert Linux kernel maintainer. Your job is to review a provided patch series and determine if it makes functional changes to the kernel that should be fuzzed. IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively use your code access tools to examine the actual source code and confirm any assumptions. Return WorthFuzzing=false if the patch only contains: - Modifications to Documentation/, Kconfig files, or code comments. - Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints. - Changes to numeric constants or macros that do not functionally alter execution flow. - Code paths that are impossible to reach in virtualized environments like GCE or QEMU, even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim). - Code in vendor-specific PCIe switch, SmartNIC, or GPU drivers (e.g., mlxsw, pds_core, qed, ionic, amdgpu) that require physical PCIe hardware cards not emulated in standard QEMU. - Driver .remove, .shutdown, or pci_unregister_driver teardown callbacks (e.g., igb_remove) that are executed only during PCI hot-unplug or sysfs driver unbind operations. If it modifies reachable core kernel logic, drivers, or architectures, use your code search tools to verify the code can be executed, then return WorthFuzzing=true. When returning WorthFuzzing=true, you MUST ALSO: 1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols. Avoid listing generic hot-path functions to prevent skewed test distributions. Prefer non-static, non-inlined API entrypoint functions over internal static helper functions (which are inlined by the compiler and do not have distinct symbol addresses). 2. Identify any specific CONFIG_ options required to properly test this new/modified feature. Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions. Also check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed for Kbuild to compile the code statically into vmlinux. List them in the EnableConfigs output array, and DO NOT add a 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4"). Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: For your convenience, here is the diff of the changes:
commit 3673dd47de278af3efbec49c7cbc842d047d7302
Author: syz-cluster <triage@syzkaller.com>
Date: Tue Aug 25 03:33:09 2026 +0000
syz-cluster: applied patch under review
diff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h
index 582d7cd4a9839..7b9cdb65deef6 100644
--- a/include/linux/sched/ext.h
+++ b/include/linux/sched/ext.h
@@ -323,7 +323,7 @@ struct scx_task_group {
u64 bw_period_us;
u64 bw_quota_us;
u64 bw_burst_us;
- bool idle;
+ bool sched_idle;
#endif
};
diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c
index c539d15cda637..4a9c382970935 100644
--- a/kernel/sched/ext/ext.c
+++ b/kernel/sched/ext/ext.c
@@ -4682,7 +4682,7 @@ void scx_tg_init(struct task_group *tg)
tg->scx.weight = CGROUP_WEIGHT_DFL;
tg->scx.bw_period_us = default_bw_period_us();
tg->scx.bw_quota_us = RUNTIME_INF;
- tg->scx.idle = false;
+ tg->scx.sched_idle = false;
}
/**
@@ -4764,7 +4764,8 @@ int scx_tg_online(struct task_group *tg)
{ .weight = tg->scx.weight,
.bw_period_us = tg->scx.bw_period_us,
.bw_quota_us = tg->scx.bw_quota_us,
- .bw_burst_us = tg->scx.bw_burst_us };
+ .bw_burst_us = tg->scx.bw_burst_us,
+ .sched_idle = tg->scx.sched_idle };
ret = SCX_CALL_OP_RET(sch, cgroup_init,
NULL, tg->css.cgroup, &args);
@@ -4934,7 +4935,7 @@ void scx_group_set_idle(struct task_group *tg, bool idle)
SCX_CALL_OP(sch, cgroup_set_idle, NULL, tg_cgrp(tg), idle);
/* Update the task group's idle state */
- tg->scx.idle = idle;
+ tg->scx.sched_idle = idle;
percpu_up_read(&scx_cgroup_ops_rwsem);
}
@@ -5185,6 +5186,7 @@ static int scx_cgroup_init(struct scx_sched *sch)
.bw_period_us = tg->scx.bw_period_us,
.bw_quota_us = tg->scx.bw_quota_us,
.bw_burst_us = tg->scx.bw_burst_us,
+ .sched_idle = tg->scx.sched_idle,
};
ret = SCX_CALL_OP_RET(sch, cgroup_init, NULL, css->cgroup, &args);
diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h
index 53e136a47924d..c6987a3a073bf 100644
--- a/kernel/sched/ext/internal.h
+++ b/kernel/sched/ext/internal.h
@@ -259,6 +259,9 @@ struct scx_cgroup_init_args {
u64 bw_period_us;
u64 bw_quota_us;
u64 bw_burst_us;
+
+ /* whether the cgroup is configured SCHED_IDLE via cpu.idle */
+ bool sched_idle;
};
enum scx_cpu_preempt_reason {
diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c
index 0554448835bd0..a17d84db93bdd 100644
--- a/kernel/sched/ext/sub.c
+++ b/kernel/sched/ext/sub.c
@@ -1361,6 +1361,7 @@ static s32 scx_cgroup_claim_subtree(struct scx_sched *sch)
.bw_period_us = tg->scx.bw_period_us,
.bw_quota_us = tg->scx.bw_quota_us,
.bw_burst_us = tg->scx.bw_burst_us,
+ .sched_idle = tg->scx.sched_idle,
};
if (tg->scx.sched != parent ||
@@ -1464,6 +1465,7 @@ static void scx_cgroup_return_subtree(struct scx_sched *sch)
.bw_period_us = tg->scx.bw_period_us,
.bw_quota_us = tg->scx.bw_quota_us,
.bw_burst_us = tg->scx.bw_burst_us,
+ .sched_idle = tg->scx.sched_idle,
};
/* the first pass must have transferred everything */
|
| 3/2 | 2026/08/25 03:33 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 3192 output: 28 thoughts: 482 Thoughts: **Analyzing the `sched_ext` Patch**
Okay, so I'm looking at this patch and my initial thought is, "Ah, it's cleaning up the `idle` naming in `scx_task_group` by renaming it to `sched_idle`." This also includes adding the `sched_idle` field to `scx_cgroup_init_args` in `kernel/sched/ext/internal.h`. I see it's propagating this new field through `scx_tg_online`, `scx_cgroup_init`, `scx_cgroup_claim_subtree`, and `scx_cgroup_return_subtree`. The key here is the functional change: passing this `sched_idle` flag down to the BPF scheduler via `struct scx_cgroup_init_args` during the `cgroup_init` BPF operation.
Let me quickly verify that `scx_cgroup_init_args` definition. Yep, `kernel/sched/ext/internal.h` confirms it:
```c
struct scx_cgroup_init_args {
u32 weight;
u64 bw_period_us;
u64 bw_quota_us;
u64 bw_burst_us;
/* whether the cgroup is configured SCHED_IDLE via cpu.idle */
bool sched_idle;
};
```
Yup, it's got the `sched_idle` boolean I expected, indicating whether the cgroup is SCHED_IDLE.
This is all within the `sched_ext` code, specifically in `ext.c` and `sub.c`. The patch touches the following functions: `scx_tg_init`, `scx_tg_online`, `scx_group_set_idle`, `scx_cgroup_init`, `scx_cgroup_claim_subtree`, and `scx_cgroup_return_subtree`. Okay, I'm starting to get the picture.
Now, the important question: is this fuzzable? Absolutely. Adding a new field to `scx_cgroup_init_args`, and critically, exposing it to BPF programs through the `cgroup_init` operation, is a clear indication that this introduces a new attack surface. I need to be sure though...
Hold on, I need to confirm: Does it *actually* expose it to BPF? Yes, the `struct scx_cgroup_init_args` *is* passed to the `cgroup_init` BPF operation, so it looks like it is.
Okay, let's just do a quick sanity check to be sure we are talking about the right thing, what is the configuration option for `sched_ext`? Is it `SCHED_CLASS_EXT` or `SCHED_EXT`? Time for a quick grep.
|
| 4/2 | 2026/08/25 03:33 | tool | grepper |
0mError:no matches Args: {
"Expression": "ext.o",
"PathPrefix": "kernel/sched/Makefile"
}Results: {
"error": "no matches"
} |
| 5/2 | 2026/08/25 03:33 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 4350 output: 32 thoughts: 11 Thoughts: Here's my take on those thoughts, tailored for an expert audience: **Diving into the Scheduler's Makefile** Okay, so I need to understand something about the scheduler build process. The logical first step, as always, is to check the `kernel/sched/Makefile`. That's where the heart of the build configuration for the scheduler components likely resides. I'm expecting to find the standard GNU Makefile structure, probably with targets for object files, dependencies, and any platform-specific optimizations or configurations. I'll be looking specifically for how the core scheduling algorithms are compiled, any custom linker flags that might be applied, and how the scheduler's various modules (if they exist) are handled. Perhaps there are conditional inclusions based on `CONFIG_` options, and I will be looking closely at how the makefile interacts with the overall kernel build system. |
| 6/2 | 2026/08/25 03:33 | tool | read-file |
0mArgs:{
"File": "kernel/sched/Makefile",
"FirstLine": 1,
"LineCount": 100
}Results: {
"Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0\n 2:\t\n 3:\tCONTEXT_ANALYSIS_core.o := y\n 4:\tCONTEXT_ANALYSIS_fair.o := y\n 5:\t\n 6:\t# The compilers are complaining about unused variables inside an if(0) scope\n 7:\t# block. This is daft, shut them up.\n 8:\tccflags-y += $(call cc-disable-warning, unused-but-set-variable)\n 9:\t\n 10:\t# These files are disabled because they produce non-interesting flaky coverage\n 11:\t# that is not a function of syscall inputs. E.g. involuntary context switches.\n 12:\tKCOV_INSTRUMENT := n\n 13:\t\n 14:\t# Disable KCSAN to avoid excessive noise and performance degradation. To avoid\n 15:\t# false positives ensure barriers implied by sched functions are instrumented.\n 16:\tKCSAN_SANITIZE := n\n 17:\tKCSAN_INSTRUMENT_BARRIERS := y\n 18:\t\n 19:\tifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)\n 20:\t# According to Alan Modra \u003calan@linuxcare.com.au\u003e, the -fno-omit-frame-pointer is\n 21:\t# needed for x86 only. Why this used to be enabled for all architectures is beyond\n 22:\t# me. I suspect most platforms don't need this, but until we know that for sure\n 23:\t# I turn this off for IA-64 only. Andreas Schwab says it's also needed on m68k\n 24:\t# to get a correct value for the wait-channel (WCHAN in ps). --davidm\n 25:\tCFLAGS_core.o := $(PROFILING) -fno-omit-frame-pointer\n 26:\tendif\n 27:\t\n 28:\t# Branch profiling isn't noinstr-safe\n 29:\tifdef CONFIG_TRACE_BRANCH_PROFILING\n 30:\tCFLAGS_build_policy.o += -DDISABLE_BRANCH_PROFILING\n 31:\tCFLAGS_build_utility.o += -DDISABLE_BRANCH_PROFILING\n 32:\tendif\n 33:\t#\n 34:\t# Build efficiency:\n 35:\t#\n 36:\t# These compilation units have roughly the same size and complexity - so their\n 37:\t# build parallelizes well and finishes roughly at once:\n 38:\t#\n 39:\tobj-y += core.o\n 40:\tobj-y += fair.o\n 41:\tobj-y += build_policy.o\n 42:\tobj-y += build_utility.o\n"
} |
| 7/2 | 2026/08/25 03:33 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 5269 output: 27 thoughts: 50 Thoughts: Okay, here's my take on those thoughts, framed as my own: **Digging into the Scheduler's Extension Modules** Hmm, this is strange. I was expecting to find `kernel/sched/ext/ext.c` referenced in the main `Makefile` for the scheduler, `kernel/sched/Makefile`. That's where I'd *normally* expect to see the build configuration for an extension. It's a bit odd to have it missing from there. Okay, let's not jump to conclusions. First, I should probably check the obvious places. I'll take a quick look at `kernel/sched/ext/Makefile` to see if it's got its own build rules – perhaps it's a completely self-contained module. Alternatively, I'll examine `kernel/sched/build_policy.c`; maybe it has some conditional inclusion logic or something related to how the scheduling policies are compiled. Let's see if either of those holds the clue I'm looking for. |
| 8/2 | 2026/08/25 03:33 | tool | grepper |
0mArgs:{
"Expression": "ext.c",
"PathPrefix": "kernel/sched/"
}Results: {
"Output": "kernel/sched/build_policy.c-65-# include \"ext/internal.h\"\nkernel/sched/build_policy.c:66:# include \"ext/cid.h\"\nkernel/sched/build_policy.c-67-# include \"ext/arena.h\"\n--\nkernel/sched/build_policy.c-70-# include \"ext/inlines.h\"\nkernel/sched/build_policy.c:71:# include \"ext/ext.c\"\nkernel/sched/build_policy.c:72:# include \"ext/cid.c\"\nkernel/sched/build_policy.c-73-# include \"ext/arena.c\"\n--\nkernel/sched/core.c=2293=void wakeup_preempt(struct rq *rq, struct task_struct *p, int flags)\n--\nkernel/sched/core.c-2296-\nkernel/sched/core.c:2297:\tif (p-\u003esched_class == rq-\u003enext_class) {\nkernel/sched/core.c:2298:\t\trq-\u003enext_class-\u003ewakeup_preempt(rq, p, flags);\nkernel/sched/core.c-2299-\nkernel/sched/core.c:2300:\t} else if (sched_class_above(p-\u003esched_class, rq-\u003enext_class)) {\nkernel/sched/core.c:2301:\t\trq-\u003enext_class-\u003ewakeup_preempt(rq, p, flags);\nkernel/sched/core.c-2302-\t\tresched_curr(rq);\nkernel/sched/core.c:2303:\t\trq-\u003enext_class = p-\u003esched_class;\nkernel/sched/core.c-2304-\t}\n--\nkernel/sched/core.c=6781=static inline struct task_struct *proxy_resched_idle(struct rq *rq)\n--\nkernel/sched/core.c-6783-\tput_prev_set_next_task(rq, rq-\u003edonor, rq-\u003eidle);\nkernel/sched/core.c:6784:\trq-\u003enext_class = \u0026idle_sched_class;\nkernel/sched/core.c-6785-\trq_set_donor(rq, rq-\u003eidle);\n--\nkernel/sched/core.c=7097=static void __sched notrace __schedule(int sched_mode)\n--\nkernel/sched/core.c-7167-\t\t\tnext = prev;\nkernel/sched/core.c:7168:\t\t\trq-\u003enext_class = \u0026idle_sched_class;\nkernel/sched/core.c-7169-\t\t\tgoto picked;\n--\nkernel/sched/core.c-7185-\tnext = pick_next_task(rq, \u0026rf);\nkernel/sched/core.c:7186:\trq-\u003enext_class = next-\u003esched_class;\nkernel/sched/core.c-7187-\tif (sched_proxy_exec()) {\n--\nkernel/sched/core.c=7663=void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)\n--\nkernel/sched/core.c-7666-\t\tDEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;\nkernel/sched/core.c:7667:\tconst struct sched_class *prev_class, *next_class;\nkernel/sched/core.c-7668-\tstruct rq_flags rf;\n--\nkernel/sched/core.c-7724-\tprev_class = p-\u003esched_class;\nkernel/sched/core.c:7725:\tnext_class = __setscheduler_class(p-\u003epolicy, prio);\nkernel/sched/core.c-7726-\nkernel/sched/core.c:7727:\tif (prev_class != next_class)\nkernel/sched/core.c-7728-\t\tqueue_flag |= DEQUEUE_CLASS;\n--\nkernel/sched/core.c-7760-\nkernel/sched/core.c:7761:\t\tp-\u003esched_class = next_class;\nkernel/sched/core.c-7762-\t\tp-\u003eprio = prio;\n--\nkernel/sched/core.c=8951=void __init sched_init(void)\n--\nkernel/sched/core.c-9048-#endif\nkernel/sched/core.c:9049:\t\trq-\u003enext_class = \u0026idle_sched_class;\nkernel/sched/core.c-9050-\n--\nkernel/sched/core.c-9135-\tinit_sched_fair_class();\nkernel/sched/core.c:9136:\tinit_sched_ext_class();\nkernel/sched/core.c-9137-\n--\nkernel/sched/core.c=11276=void sched_change_end(struct sched_change_ctx *ctx)\n--\nkernel/sched/core.c-11307-\t\t\tif (sched_class_above(p-\u003esched_class, ctx-\u003eclass)) {\nkernel/sched/core.c:11308:\t\t\t\trq-\u003enext_class-\u003ewakeup_preempt(rq, p, 0);\nkernel/sched/core.c:11309:\t\t\t\trq-\u003enext_class = p-\u003esched_class;\nkernel/sched/core.c-11310-\t\t\t}\n--\nkernel/sched/deadline.c=1141=static enum hrtimer_restart dl_server_timer(struct hrtimer *timer, struct sched_dl_entity *dl_se)\n--\nkernel/sched/deadline.c-1208- * updating (and the queueing back to dl_rq) will be done by the\nkernel/sched/deadline.c:1209: * next call to enqueue_task_dl().\nkernel/sched/deadline.c-1210- */\n--\nkernel/sched/ext/cid.c=180=s32 scx_cid_init(struct scx_sched *sch)\n--\nkernel/sched/ext/cid.c-188-\tstruct scx_cid_tables *tbls;\nkernel/sched/ext/cid.c:189:\tu32 next_cid = 0;\nkernel/sched/ext/cid.c:190:\ts32 next_node_idx = 0, next_llc_idx = 0, next_core_idx = 0;\nkernel/sched/ext/cid.c-191-\ts32 next_shard_idx = 0;\n--\nkernel/sched/ext/cid.c-229-\twhile (!cpumask_empty(to_walk)) {\nkernel/sched/ext/cid.c:230:\t\ts32 next_cpu = cpumask_first(to_walk);\nkernel/sched/ext/cid.c:231:\t\ts32 nid = cpu_to_node(next_cpu);\nkernel/sched/ext/cid.c:232:\t\ts32 node_cid = next_cid;\nkernel/sched/ext/cid.c-233-\t\ts32 node_idx;\n--\nkernel/sched/ext/cid.c-239-\t\tif (nid \u003c 0) {\nkernel/sched/ext/cid.c:240:\t\t\tcpumask_clear_cpu(next_cpu, to_walk);\nkernel/sched/ext/cid.c-241-\t\t\tcontinue;\n--\nkernel/sched/ext/cid.c-247-\t\tcpumask_and(node_scratch, to_walk, cpumask_of_node(nid));\nkernel/sched/ext/cid.c:248:\t\tif (WARN_ON_ONCE(!cpumask_test_cpu(next_cpu, node_scratch)))\nkernel/sched/ext/cid.c-249-\t\t\treturn -EINVAL;\n--\nkernel/sched/ext/cid.c-253-\t\t\tconst struct cpumask *llc_mask = cpu_llc_mask(ncpu, llc_fallback);\nkernel/sched/ext/cid.c:254:\t\t\ts32 llc_cid = next_cid;\nkernel/sched/ext/cid.c-255-\t\t\ts32 llc_idx = next_llc_idx++;\n--\nkernel/sched/ext/cid.c-265-\t\t\tcalc_shard_layout(llc_scratch, shard_size, \u0026cores_per_shard, \u0026nr_large);\nkernel/sched/ext/cid.c:266:\t\t\tshard_cid = next_cid;\nkernel/sched/ext/cid.c-267-\t\t\tshard_idx = next_shard_idx++;\n--\nkernel/sched/ext/cid.c-272-\t\t\t\tconst struct cpumask *sib = topology_sibling_cpumask(lcpu);\nkernel/sched/ext/cid.c:273:\t\t\t\ts32 core_cid = next_cid;\nkernel/sched/ext/cid.c:274:\t\t\t\ts32 core_idx = next_core_idx++;\nkernel/sched/ext/cid.c-275-\t\t\t\ts32 ccpu;\n--\nkernel/sched/ext/cid.c-296-\t\t\t\t\tcids_in_shard = 0;\nkernel/sched/ext/cid.c:297:\t\t\t\t\tshard_cid = next_cid;\nkernel/sched/ext/cid.c-298-\t\t\t\t\tshard_idx = next_shard_idx++;\n--\nkernel/sched/ext/cid.c-304-\t\t\t\tfor_each_cpu(ccpu, core_scratch) {\nkernel/sched/ext/cid.c:305:\t\t\t\t\ts32 cid = next_cid++;\nkernel/sched/ext/cid.c-306-\n--\nkernel/sched/ext/cid.c-346-\nkernel/sched/ext/cid.c:347:\t\tcid = next_cid++;\nkernel/sched/ext/cid.c-348-\t\ttbls-\u003ecid_to_cpu[cid] = cpu;\n--\nkernel/sched/ext/cid.c-375-\t */\nkernel/sched/ext/cid.c:376:\tfor (cid = 0; cid \u003c next_cid; cid++) {\nkernel/sched/ext/cid.c-377-\t\ts32 sidx = tbls-\u003ecid_to_shard[cid];\n--\nkernel/sched/ext/ext.c=354=static bool rq_is_open(struct rq *rq, u64 enq_flags)\n--\nkernel/sched/ext/ext.c-361-\t */\nkernel/sched/ext/ext.c:362:\tif (sched_class_above(rq-\u003enext_class, \u0026ext_sched_class))\nkernel/sched/ext/ext.c-363-\t\treturn false;\n--\nkernel/sched/ext/ext.c-368-\t */\nkernel/sched/ext/ext.c:369:\tif (sched_class_above(\u0026ext_sched_class, rq-\u003enext_class))\nkernel/sched/ext/ext.c-370-\t\treturn true;\n--\nkernel/sched/ext/ext.c=1518=static void rq_owned_post_enq(struct scx_sched *sch, struct rq *rq,\n--\nkernel/sched/ext/ext.c-1559-\t * purpose, but for it to be invoked, we must ensure that we bump\nkernel/sched/ext/ext.c:1560:\t * @rq-\u003enext_class to \u0026ext_sched_class if it's currently idle.\nkernel/sched/ext/ext.c-1561-\t *\nkernel/sched/ext/ext.c-1562-\t * wakeup_preempt() does the bumping, and since we only invoke it if\nkernel/sched/ext/ext.c:1563:\t * @rq-\u003enext_class is below \u0026ext_sched_class, it will also\nkernel/sched/ext/ext.c-1564-\t * resched_curr(rq).\nkernel/sched/ext/ext.c-1565-\t */\nkernel/sched/ext/ext.c:1566:\tif (sched_class_above(p-\u003esched_class, rq-\u003enext_class))\nkernel/sched/ext/ext.c-1567-\t\twakeup_preempt(rq, p, 0);\n--\nkernel/sched/ext/ext.c-1573-\t * Note that the wakeup_preempt() above may have already triggered\nkernel/sched/ext/ext.c:1574:\t * a resched if @rq-\u003enext_class was idle. It's harmless, since\nkernel/sched/ext/ext.c-1575-\t * need_resched is cleared immediately after task pick.\n--\nkernel/sched/ext/ext.c=3077=static void switch_class(struct rq *rq, struct task_struct *next)\n--\nkernel/sched/ext/ext.c-3079-\tstruct scx_sched *sch = scx_root_protected_live();\nkernel/sched/ext/ext.c:3080:\tconst struct sched_class *next_class = next-\u003esched_class;\nkernel/sched/ext/ext.c-3081-\n--\nkernel/sched/ext/ext.c-3087-\t * longer under the control of SCX. Therefore, don't invoke the callback\nkernel/sched/ext/ext.c:3088:\t * if the next class is below SCX (in which case the BPF scheduler has\nkernel/sched/ext/ext.c-3089-\t * actively decided not to schedule any tasks on the CPU).\nkernel/sched/ext/ext.c-3090-\t */\nkernel/sched/ext/ext.c:3091:\tif (sched_class_above(\u0026ext_sched_class, next_class))\nkernel/sched/ext/ext.c-3092-\t\treturn;\n--\nkernel/sched/ext/ext.c-3105-\t\t\tstruct scx_cpu_release_args args = {\nkernel/sched/ext/ext.c:3106:\t\t\t\t.reason = preempt_reason_from_class(next_class),\nkernel/sched/ext/ext.c-3107-\t\t\t\t.task = next,\n--\nkernel/sched/ext/ext.c=5551=bool scx_allow_ttwu_queue(const struct task_struct *p)\n--\nkernel/sched/ext/ext.c-5571-/**\nkernel/sched/ext/ext.c:5572: * handle_lockup - sched_ext common lockup handler\nkernel/sched/ext/ext.c-5573- * @exit_cpu: CPU to record in exit_info. Pass the stalled/hung CPU, not current.\n--\nkernel/sched/ext/ext.c=8661=static struct notifier_block scx_pm_notifier = {\n--\nkernel/sched/ext/ext.c-8664-\nkernel/sched/ext/ext.c:8665:void __init init_sched_ext_class(void)\nkernel/sched/ext/ext.c-8666-{\n--\nkernel/sched/ext/ext.c=10898=static int __init scx_init(void)\n--\nkernel/sched/ext/ext.c-10975-\t/*\nkernel/sched/ext/ext.c:10976:\t * kfunc registration can't be done from init_sched_ext_class() as\nkernel/sched/ext/ext.c-10977-\t * register_btf_kfunc_id_set() needs most of the system to be up.\n--\nkernel/sched/ext/ext.h=22=bool scx_allow_ttwu_queue(const struct task_struct *p);\nkernel/sched/ext/ext.h:23:void init_sched_ext_class(void);\nkernel/sched/ext/ext.h-24-\n--\nkernel/sched/ext/ext.h=56=static inline bool scx_allow_ttwu_queue(const struct task_struct *p) { return true; }\nkernel/sched/ext/ext.h:57:static inline void init_sched_ext_class(void) {}\nkernel/sched/ext/ext.h-58-\n--\nkernel/sched/ext/idle.c=913=static bool check_builtin_idle_enabled(struct scx_sched *sch)\n--\nkernel/sched/ext/idle.c-926- * We can't simply check whether @p-\u003emigration_disabled is set in a\nkernel/sched/ext/idle.c:927: * sched_ext callback, because the BPF prolog (__bpf_prog_enter) may disable\nkernel/sched/ext/idle.c-928- * migration for the current task while running BPF code.\n--\nkernel/sched/ext/idle.c=1525=static const struct btf_kfunc_id_set scx_kfunc_set_idle = {\n--\nkernel/sched/ext/idle.c-1537- *\nkernel/sched/ext/idle.c:1538: * These kfuncs are also members of scx_kfunc_ids_unlocked (see ext.c) because\nkernel/sched/ext/idle.c-1539- * they're callable from unlocked contexts in addition to ops.select_cpu() and\n--\nkernel/sched/ext/internal.h=132=enum scx_ops_flags {\n--\nkernel/sched/ext/internal.h-138-\t/*\nkernel/sched/ext/internal.h:139:\t * By default, if there are no other task to run on the CPU, ext core\nkernel/sched/ext/internal.h-140-\t * keeps running the current task even after its slice expires. If this\n--\nkernel/sched/ext/internal.h=322=struct sched_ext_ops {\n--\nkernel/sched/ext/internal.h-372-\t *\nkernel/sched/ext/internal.h:373:\t * The ext core keeps track of whether the BPF side owns a given task or\nkernel/sched/ext/internal.h-374-\t * not and can gracefully ignore spurious dispatches from BPF side,\n--\nkernel/sched/ext/internal.h=1431=enum scx_cap_flags {\n--\nkernel/sched/ext/internal.h-1482- * delivery is in flight per shard. Further changes fold into the same buffer\nkernel/sched/ext/internal.h:1483: * and ship as the next callback, so a shard's callbacks fire in order.\nkernel/sched/ext/internal.h-1484- *\n--\nkernel/sched/ext/internal.h=1672=enum scx_enq_flags {\n--\nkernel/sched/ext/internal.h-1725-\t * The task being enqueued is the only task available for the cpu. By\nkernel/sched/ext/internal.h:1726:\t * default, ext core keeps executing such tasks but when\nkernel/sched/ext/internal.h-1727-\t * %SCX_OPS_ENQ_LAST is specified, they're ops.enqueue()'d with the\n--\nkernel/sched/ext/internal.h=1829=static const char *scx_enable_state_str[] = {\n--\nkernel/sched/ext/internal.h-1838- *\nkernel/sched/ext/internal.h:1839: * The sched_ext core uses this state machine to track task ownership\nkernel/sched/ext/internal.h-1840- * between the SCX core and the BPF scheduler. This allows the BPF\n--\nkernel/sched/ext/internal.h-1911- *\nkernel/sched/ext/internal.h:1912: * The sched_ext core uses a \"lock dancing\" protocol coordinated by\nkernel/sched/ext/internal.h-1913- * p-\u003escx.holding_cpu. When moving a task to a different rq:\n--\nkernel/sched/ext/sub.c-10- * sub-scheduler enable/disable paths. The core dispatch/enqueue machinery it\nkernel/sched/ext/sub.c:11: * builds on lives in ext.c.\nkernel/sched/ext/sub.c-12- *\n--\nkernel/sched/ext/sub.c=1232=void drain_descendants(struct scx_sched *sch)\n--\nkernel/sched/ext/sub.c-1249- * state to %SCX_TASK_READY to account for the already completed init. A task\nkernel/sched/ext/sub.c:1250: * on a non-ext class, possible under an %SCX_OPS_SWITCH_PARTIAL root, stays\nkernel/sched/ext/sub.c-1251- * %READY and is enabled by switching_to_scx() if it switches over.\n--\nkernel/sched/ext/sub.c=1711=void scx_sub_enable_workfn(struct kthread_work *work)\n--\nkernel/sched/ext/sub.c-1956-\t\t\t * is what we want. Assign it to @sch and, if it's on\nkernel/sched/ext/sub.c:1957:\t\t\t * the ext class, enable. A non-ext task, possible under\nkernel/sched/ext/sub.c-1958-\t\t\t * an %SCX_OPS_SWITCH_PARTIAL root, stays READY and is\n--\nkernel/sched/fair.c=6978=static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)\n--\nkernel/sched/fair.c-7032-\t * current donor. In case of proxy-execution, the execution\nkernel/sched/fair.c:7033:\t * context cannot exit to the userspace while holding a mutex\nkernel/sched/fair.c-7034-\t * and the rule of throttle deferral to only throttle the\n--\nkernel/sched/fair.c=15452=int sched_group_set_idle(struct task_group *tg, long idle)\n--\nkernel/sched/fair.c-15482-\t\tif (WARN_ON_ONCE(was_idle == cfs_rq_is_idle(grp_cfs_rq)))\nkernel/sched/fair.c:15483:\t\t\tgoto next_cpu;\nkernel/sched/fair.c-15484-\n--\nkernel/sched/fair.c-15502-\nkernel/sched/fair.c:15503:next_cpu:\nkernel/sched/fair.c-15504-\t\trq_unlock_irqrestore(rq, \u0026rf);\n--\nkernel/sched/rt.c=2078=static void push_rt_tasks(struct rq *rq)\n--\nkernel/sched/rt.c-2127- */\nkernel/sched/rt.c:2128:static int rto_next_cpu(struct root_domain *rd)\nkernel/sched/rt.c-2129-{\n--\nkernel/sched/rt.c-2135-\t * When starting the IPI RT pushing, the rto_cpu is set to -1,\nkernel/sched/rt.c:2136:\t * rt_next_cpu() will simply return the first CPU found in\nkernel/sched/rt.c-2137-\t * the rto_mask.\nkernel/sched/rt.c-2138-\t *\nkernel/sched/rt.c:2139:\t * If rto_next_cpu() is called with rto_cpu is a valid CPU, it\nkernel/sched/rt.c-2140-\t * will return the next CPU found in the rto_mask.\n--\nkernel/sched/rt.c=2190=static void tell_cpu_to_push(struct rq *rq)\n--\nkernel/sched/rt.c-2209-\tif (rq-\u003erd-\u003erto_cpu \u003c 0)\nkernel/sched/rt.c:2210:\t\tcpu = rto_next_cpu(rq-\u003erd);\nkernel/sched/rt.c-2211-\n--\nkernel/sched/rt.c=2224=void rto_push_irq_work_func(struct irq_work *work)\n--\nkernel/sched/rt.c-2246-\t/* Pass the IPI to the next rt overloaded queue */\nkernel/sched/rt.c:2247:\tcpu = rto_next_cpu(rd);\nkernel/sched/rt.c-2248-\n--\nkernel/sched/sched.h=1159=struct rq {\n--\nkernel/sched/sched.h-1187-\t/*\nkernel/sched/sched.h:1188:\t * The next cacheline holds the (hot) runqueue lock, as well as\nkernel/sched/sched.h-1189-\t * some other less performance-critical fields.\n--\nkernel/sched/sched.h-1251-\tstruct task_struct\t*stop;\nkernel/sched/sched.h:1252:\tconst struct sched_class *next_class;\nkernel/sched/sched.h-1253-\tunsigned long\t\tnext_balance;\n--\nkernel/sched/sched.h=2867=static inline void rq_modified_begin(struct rq *rq, const struct sched_class *class)\nkernel/sched/sched.h-2868-{\nkernel/sched/sched.h:2869:\tif (sched_class_above(rq-\u003enext_class, class))\nkernel/sched/sched.h:2870:\t\trq-\u003enext_class = class;\nkernel/sched/sched.h-2871-}\n--\nkernel/sched/sched.h=2873=static inline bool rq_modified_above(struct rq *rq, const struct sched_class *class)\nkernel/sched/sched.h-2874-{\nkernel/sched/sched.h:2875:\treturn sched_class_above(rq-\u003enext_class, class);\nkernel/sched/sched.h-2876-}\n--\nkernel/sched/syscalls.c=493=int __sched_setscheduler(struct task_struct *p,\n--\nkernel/sched/syscalls.c-498-\tint retval, oldprio, newprio;\nkernel/sched/syscalls.c:499:\tconst struct sched_class *prev_class, *next_class;\nkernel/sched/syscalls.c-500-\tstruct balance_callback *head;\n--\nkernel/sched/syscalls.c-675-\tprev_class = p-\u003esched_class;\nkernel/sched/syscalls.c:676:\tnext_class = __setscheduler_class(policy, newprio);\nkernel/sched/syscalls.c-677-\nkernel/sched/syscalls.c:678:\tif (prev_class != next_class)\nkernel/sched/syscalls.c-679-\t\tqueue_flags |= DEQUEUE_CLASS;\n--\nkernel/sched/syscalls.c-684-\t\t\t__setscheduler_params(p, attr);\nkernel/sched/syscalls.c:685:\t\t\tp-\u003esched_class = next_class;\nkernel/sched/syscalls.c-686-\t\t\tp-\u003eprio = newprio;\n"
} |
| 9/2 | 2026/08/25 03:33 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 12353 output: 30 thoughts: 107 Thoughts: **Investigating the Extension Scheduler Integration** Okay, so it looks like `kernel/sched/ext/ext.c` is being included within `kernel/sched/build_policy.c`. Interesting. I should probably re-examine both `kernel/sched/build_policy.c` and the associated `Makefile` in the `kernel/sched` directory. I'm trying to get a clearer picture of how this extension scheduler is being integrated. Wait a second… I've got it. The compilation of `kernel/sched/ext/ext.c` is conditional – it's only included when `CONFIG_SCHED_CLASS_EXT` is enabled. That makes more sense. Now I need to find where that configuration option is defined. Let me check the `kernel/sched/Kconfig` file or another related configuration file to see how `SCHED_CLASS_EXT` is exposed and controlled. That should explain the whole picture. |
| 10/2 | 2026/08/25 03:33 | tool | grepper |
0mArgs:{
"Expression": "SCHED_CLASS_EXT",
"PathPrefix": "kernel/sched/"
}Results: {
"Output": "kernel/sched/build_policy.c-59-\nkernel/sched/build_policy.c:60:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/build_policy.c-61-# include \u003clinux/btf_ids.h\u003e\n--\nkernel/sched/core.c=227=static inline bool prio_less(const struct task_struct *a,\n--\nkernel/sched/core.c-260-\nkernel/sched/core.c:261:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/core.c-262-\tif (pa == MAX_RT_PRIO + MAX_NICE + 1)\t/* ext */\n--\nkernel/sched/core.c=4573=static void __sched_fork(u64 clone_flags, struct task_struct *p)\n--\nkernel/sched/core.c-4610-\nkernel/sched/core.c:4611:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/core.c-4612-\tinit_scx_entity(\u0026p-\u003escx);\n--\nkernel/sched/core.c=4813=int sched_fork(u64 clone_flags, struct task_struct *p)\n--\nkernel/sched/core.c-4860-\t\tp-\u003esched_class = \u0026rt_sched_class;\nkernel/sched/core.c:4861:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/core.c-4862-\t} else if (task_should_scx(p-\u003epolicy)) {\n--\nkernel/sched/core.c=7608=const struct sched_class *__setscheduler_class(int policy, int prio)\n--\nkernel/sched/core.c-7615-\nkernel/sched/core.c:7616:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/core.c-7617-\tif (task_should_scx(policy))\n--\nkernel/sched/core.c=8868=int sched_cpu_dying(unsigned int cpu)\n--\nkernel/sched/core.c-8882-\tdl_server_stop(\u0026rq-\u003efair_server);\nkernel/sched/core.c:8883:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/core.c-8884-\tdl_server_stop(\u0026rq-\u003eext_server);\n--\nkernel/sched/core.c=8951=void __init sched_init(void)\n--\nkernel/sched/core.c-8960-\tBUG_ON(!sched_class_above(\u0026fair_sched_class, \u0026idle_sched_class));\nkernel/sched/core.c:8961:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/core.c-8962-\tBUG_ON(!sched_class_above(\u0026fair_sched_class, \u0026ext_sched_class));\n--\nkernel/sched/core.c-9078-\t\tfair_server_init(rq);\nkernel/sched/core.c:9079:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/core.c-9080-\t\text_server_init(rq);\n--\nkernel/sched/deadline.c=108=static inline u8 dl_get_type(struct sched_dl_entity *dl_se, struct rq *rq)\n--\nkernel/sched/deadline.c-113-\t\treturn DL_SERVER_FAIR;\nkernel/sched/deadline.c:114:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/deadline.c-115-\tif (dl_se == \u0026rq-\u003eext_server)\n--\nkernel/sched/deadline.c=1842=void sched_init_dl_servers(void)\n--\nkernel/sched/deadline.c-1866-\nkernel/sched/deadline.c:1867:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/deadline.c-1868-\t\tdl_se = \u0026rq-\u003eext_server;\n--\nkernel/sched/deadline.c=3451=static void dl_server_add_bw(struct root_domain *rd, int cpu)\n--\nkernel/sched/deadline.c-3458-\nkernel/sched/deadline.c:3459:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/deadline.c-3460-\tdl_se = \u0026cpu_rq(cpu)-\u003eext_server;\n--\nkernel/sched/deadline.c=3466=static u64 dl_server_read_bw(int cpu)\n--\nkernel/sched/deadline.c-3473-\nkernel/sched/deadline.c:3474:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/deadline.c-3475-\tif (cpu_rq(cpu)-\u003eext_server.dl_server \u0026\u0026\n--\nkernel/sched/debug.c=494=static struct dentry *debugfs_sched;\nkernel/sched/debug.c-495-\nkernel/sched/debug.c:496:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/debug.c-497-static ssize_t\n--\nkernel/sched/debug.c=561=static void debugfs_ext_server_init(void)\n--\nkernel/sched/debug.c-580-}\nkernel/sched/debug.c:581:#endif /* CONFIG_SCHED_CLASS_EXT */\nkernel/sched/debug.c-582-\n--\nkernel/sched/debug.c=712=static __init int sched_init_debug(void)\n--\nkernel/sched/debug.c-769-\tdebugfs_fair_server_init();\nkernel/sched/debug.c:770:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/debug.c-771-\tdebugfs_ext_server_init();\n--\nkernel/sched/debug.c=1406=void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,\n--\nkernel/sched/debug.c-1505-\t}\nkernel/sched/debug.c:1506:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/debug.c-1507-\t__PS(\"ext.enabled\", task_on_scx(p));\n--\nkernel/sched/ext/ext.c=641=void scx_set_task_state(struct task_struct *p, u32 state)\n--\nkernel/sched/ext/ext.c-697- * scx_tasks can be removed in favor of always using cgroup iteration if\nkernel/sched/ext/ext.c:698: * CONFIG_SCHED_CLASS_EXT depends on CONFIG_CGROUPS.\nkernel/sched/ext/ext.c-699- *\n--\nkernel/sched/ext/ext.h-8- */\nkernel/sched/ext/ext.h:9:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/ext/ext.h-10-\n--\nkernel/sched/ext/ext.h=39=bool scx_prio_less(const struct task_struct *a, const struct task_struct *b,\n--\nkernel/sched/ext/ext.h-42-\nkernel/sched/ext/ext.h:43:#else\t/* CONFIG_SCHED_CLASS_EXT */\nkernel/sched/ext/ext.h-44-\n--\nkernel/sched/ext/ext.h=57=static inline void init_sched_ext_class(void) {}\nkernel/sched/ext/ext.h-58-\nkernel/sched/ext/ext.h:59:#endif\t/* CONFIG_SCHED_CLASS_EXT */\nkernel/sched/ext/ext.h-60-\nkernel/sched/ext/ext.h:61:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/ext/ext.h-62-void __scx_update_idle(struct rq *rq, bool idle, bool do_notify);\n--\nkernel/sched/idle.c=557=static void update_curr_idle(struct rq *rq)\n--\nkernel/sched/idle.c-569-\tdl_server_update_idle(\u0026rq-\u003efair_server, delta_exec);\nkernel/sched/idle.c:570:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/idle.c-571-\tdl_server_update_idle(\u0026rq-\u003eext_server, delta_exec);\n--\nkernel/sched/sched.h=194=static inline int normal_policy(int policy)\nkernel/sched/sched.h-195-{\nkernel/sched/sched.h:196:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/sched.h-197-\tif (policy == SCHED_EXT)\n--\nkernel/sched/sched.h=681=struct cfs_rq {\n--\nkernel/sched/sched.h-779-\nkernel/sched/sched.h:780:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/sched.h-781-/* scx_rq-\u003eflags, protected by the rq lock */\n--\nkernel/sched/sched.h=811=struct scx_rq {\n--\nkernel/sched/sched.h-850-};\nkernel/sched/sched.h:851:#endif /* CONFIG_SCHED_CLASS_EXT */\nkernel/sched/sched.h-852-\n--\nkernel/sched/sched.h=1159=struct rq {\n--\nkernel/sched/sched.h-1213-\tstruct dl_rq\t\tdl;\nkernel/sched/sched.h:1214:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/sched.h-1215-\tstruct scx_rq\t\tscx;\n--\nkernel/sched/sched.h=1885=extern struct balance_callback balance_push_callback;\nkernel/sched/sched.h-1886-\nkernel/sched/sched.h:1887:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/sched.h-1888-extern const struct sched_class ext_sched_class;\n--\nkernel/sched/sched.h=1904=static inline void scx_rq_clock_invalidate(struct rq *rq)\n--\nkernel/sched/sched.h-1910-\nkernel/sched/sched.h:1911:#else /* !CONFIG_SCHED_CLASS_EXT: */\nkernel/sched/sched.h-1912-#define scx_enabled()\t\tfalse\n--\nkernel/sched/sched.h=1916=static inline void scx_rq_clock_invalidate(struct rq *rq) {}\nkernel/sched/sched.h:1917:#endif /* !CONFIG_SCHED_CLASS_EXT */\nkernel/sched/sched.h-1918-\n--\nkernel/sched/sched.h=2841=static inline const struct sched_class *next_active_class(const struct sched_class *class)\n--\nkernel/sched/sched.h-2843-\tclass++;\nkernel/sched/sched.h:2844:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/sched.h-2845-\tif (scx_switched_all() \u0026\u0026 class == \u0026fair_sched_class)\n--\nkernel/sched/topology.c=474=void rq_attach_root(struct rq *rq, struct root_domain *rd)\n--\nkernel/sched/topology.c-512-\nkernel/sched/topology.c:513:#ifdef CONFIG_SCHED_CLASS_EXT\nkernel/sched/topology.c-514-\tif (rq-\u003eext_server.dl_server)\n"
} |
| 11/2 | 2026/08/25 03:33 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 15607 output: 30 thoughts: 135 Thoughts: **Analyzing the Extended Scheduler Configuration** Okay, so the primary configuration involved here is `SCHED_CLASS_EXT`. I need to figure out how this patch interacts with it. Hmm, the code seems to be focused around `scx_cgroup_init_args`. That's used in several key functions: `scx_cgroup_init`, `scx_cgroup_claim_subtree`, and `scx_cgroup_return_subtree`. All of these, the code tells me, are located within `kernel/sched/ext/ext.c` and `kernel/sched/ext/sub.c`. Right, `SCHED_CLASS_EXT`… making a note to keep that configuration in mind as I process this. Hang on, I need to make sure I haven't missed any other potentially relevant configurations. Let me quickly scan `kernel/sched/ext/ext.c` and search for anything related to `cgroup_init` to confirm that I am not missing anything obvious. |
| 12/2 | 2026/08/25 03:33 | tool | grepper |
0mArgs:{
"Expression": "cgroup_init",
"PathPrefix": "kernel/sched/ext/"
}Results: {
"Output": "kernel/sched/ext/ext.c=4680=void scx_tg_init(struct task_group *tg)\n--\nkernel/sched/ext/ext.c-4691- *\nkernel/sched/ext/ext.c:4692: * Return the sched that @tg's ops.cgroup_init() succeeded on, %NULL if @tg\nkernel/sched/ext/ext.c-4693- * isn't inited. An autogroup tg has no cgroup of its own and resolves to the\n--\nkernel/sched/ext/ext.c=4705=static struct scx_sched *scx_tg_sched(struct task_group *tg)\n--\nkernel/sched/ext/ext.c-4711-\t\ttg = \u0026root_task_group;\nkernel/sched/ext/ext.c:4712:\t/* INITED means ops.cgroup_init() succeeded on @tg-\u003escx.sched */\nkernel/sched/ext/ext.c-4713-\treturn (tg-\u003escx.flags \u0026 SCX_TG_INITED) ? tg-\u003escx.sched : NULL;\n--\nkernel/sched/ext/ext.c-4725- * Return %NULL if the parent task_group has no sched. That can happen when the\nkernel/sched/ext/ext.c:4726: * parent's ops.cgroup_init() fails while a sub-scheduler is being disabled.\nkernel/sched/ext/ext.c-4727- *\n--\nkernel/sched/ext/ext.c=4742=int scx_tg_online(struct task_group *tg)\n--\nkernel/sched/ext/ext.c-4761-\nkernel/sched/ext/ext.c:4762:\t\tif (SCX_HAS_OP(sch, cgroup_init)) {\nkernel/sched/ext/ext.c:4763:\t\t\tstruct scx_cgroup_init_args args =\nkernel/sched/ext/ext.c-4764-\t\t\t\t{ .weight = tg-\u003escx.weight,\n--\nkernel/sched/ext/ext.c-4769-\nkernel/sched/ext/ext.c:4770:\t\t\tret = SCX_CALL_OP_RET(sch, cgroup_init,\nkernel/sched/ext/ext.c-4771-\t\t\t\t\t NULL, tg-\u003ecss.cgroup, \u0026args);\nkernel/sched/ext/ext.c-4772-\t\t\tif (ret)\nkernel/sched/ext/ext.c:4773:\t\t\t\tret = scx_ops_sanitize_err(sch, \"cgroup_init\", ret);\nkernel/sched/ext/ext.c-4774-\t\t}\n--\nkernel/sched/ext/ext.c=5147=static void scx_cgroup_exit(struct scx_sched *sch)\n--\nkernel/sched/ext/ext.c-5157-\nkernel/sched/ext/ext.c:5158:\t\t/* also clear the sched of tgs whose ops.cgroup_init() failed */\nkernel/sched/ext/ext.c-5159-\t\ttg-\u003escx.sched = NULL;\n--\nkernel/sched/ext/ext.c-5167-\nkernel/sched/ext/ext.c:5168:static int scx_cgroup_init(struct scx_sched *sch)\nkernel/sched/ext/ext.c-5169-{\n--\nkernel/sched/ext/ext.c-5182-\nkernel/sched/ext/ext.c:5183:\t\tif (sch-\u003eops.cgroup_init) {\nkernel/sched/ext/ext.c:5184:\t\t\tstruct scx_cgroup_init_args args = {\nkernel/sched/ext/ext.c-5185-\t\t\t\t.weight = tg-\u003escx.weight,\n--\nkernel/sched/ext/ext.c-5191-\nkernel/sched/ext/ext.c:5192:\t\t\tret = SCX_CALL_OP_RET(sch, cgroup_init, NULL, css-\u003ecgroup, \u0026args);\nkernel/sched/ext/ext.c-5193-\t\t\tif (ret) {\nkernel/sched/ext/ext.c:5194:\t\t\t\tscx_error(sch, \"ops.cgroup_init() failed (%d)\", ret);\nkernel/sched/ext/ext.c-5195-\t\t\t\treturn ret;\n--\nkernel/sched/ext/ext.c=5207=static void scx_cgroup_exit(struct scx_sched *sch) {}\nkernel/sched/ext/ext.c:5208:static int scx_cgroup_init(struct scx_sched *sch) { return 0; }\nkernel/sched/ext/ext.c-5209-#endif\n--\nkernel/sched/ext/ext.c=7468=static void scx_root_enable_workfn(struct kthread_work *work)\n--\nkernel/sched/ext/ext.c-7710-\tset_cgroup_sched(sch_cgroup(sch), sch);\nkernel/sched/ext/ext.c:7711:\tret = scx_cgroup_init(sch);\nkernel/sched/ext/ext.c-7712-\tif (ret)\n--\nkernel/sched/ext/ext.c=8072=static int bpf_scx_check_member(const struct btf_type *t,\n--\nkernel/sched/ext/ext.c-8080-#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c:8081:\tcase offsetof(struct sched_ext_ops, cgroup_init):\nkernel/sched/ext/ext.c-8082-\tcase offsetof(struct sched_ext_ops, cgroup_exit):\n--\nkernel/sched/ext/ext.c=8237=static void sched_ext_ops__disable(struct task_struct *p) {}\nkernel/sched/ext/ext.c-8238-#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c:8239:static s32 sched_ext_ops__cgroup_init(struct cgroup *cgrp, struct scx_cgroup_init_args *args) { return -EINVAL; }\nkernel/sched/ext/ext.c-8240-static void sched_ext_ops__cgroup_exit(struct cgroup *cgrp) {}\n--\nkernel/sched/ext/ext.c=8259=static struct sched_ext_ops __bpf_ops_sched_ext_ops = {\n--\nkernel/sched/ext/ext.c-8280-#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c:8281:\t.cgroup_init\t\t= sched_ext_ops__cgroup_init,\nkernel/sched/ext/ext.c-8282-\t.cgroup_exit\t\t= sched_ext_ops__cgroup_exit,\n--\nkernel/sched/ext/ext.c=8326=static struct sched_ext_ops_cid __bpf_ops_sched_ext_ops_cid = {\n--\nkernel/sched/ext/ext.c-8345-#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c:8346:\t.cpuctl_init\t\t= sched_ext_ops__cgroup_init,\nkernel/sched/ext/ext.c-8347-\t.cpuctl_exit\t\t= sched_ext_ops__cgroup_exit,\n--\nkernel/sched/ext/ext.c=10783=static const u32 scx_kf_allow_flags[] = {\n--\nkernel/sched/ext/ext.c-10790-#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c:10791:\t[SCX_OP_IDX(cgroup_init)]\t= SCX_KF_ALLOW_UNLOCKED,\nkernel/sched/ext/ext.c-10792-\t[SCX_OP_IDX(cgroup_exit)]\t= SCX_KF_ALLOW_UNLOCKED,\n--\nkernel/sched/ext/ext.c=10898=static int __init scx_init(void)\n--\nkernel/sched/ext/ext.c-10954-#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c:10955:\tCID_OFFSET_MATCH(cgroup_init, cpuctl_init);\nkernel/sched/ext/ext.c-10956-\tCID_OFFSET_MATCH(cgroup_exit, cpuctl_exit);\n--\nkernel/sched/ext/internal.h=248=struct scx_exit_task_args {\n--\nkernel/sched/ext/internal.h-252-\nkernel/sched/ext/internal.h:253:/* argument container for ops.cgroup_init() */\nkernel/sched/ext/internal.h:254:struct scx_cgroup_init_args {\nkernel/sched/ext/internal.h-255-\t/* the weight of the cgroup [1..10000] */\n--\nkernel/sched/ext/internal.h=322=struct sched_ext_ops {\n--\nkernel/sched/ext/internal.h-653-\t/**\nkernel/sched/ext/internal.h:654:\t * @cgroup_init: Initialize a cgroup\nkernel/sched/ext/internal.h-655-\t * @cgrp: cgroup being initialized\n--\nkernel/sched/ext/internal.h-662-\t * Cgroup handovers also generate these ops: an enabling sub-scheduler\nkernel/sched/ext/internal.h:663:\t * receives ops.cgroup_init() for every cgroup in its subtree while the\nkernel/sched/ext/internal.h-664-\t * previous sched receives ops.cgroup_exit(), and disabling reverses the\n--\nkernel/sched/ext/internal.h-675-\t */\nkernel/sched/ext/internal.h:676:\ts32 (*cgroup_init)(struct cgroup *cgrp,\nkernel/sched/ext/internal.h:677:\t\t\t struct scx_cgroup_init_args *args);\nkernel/sched/ext/internal.h-678-\n--\nkernel/sched/ext/internal.h-683-\t * Exit @cgrp for sched_ext, delivered to the sched whose\nkernel/sched/ext/internal.h:684:\t * ops.cgroup_init() it pairs with, either when the BPF scheduler is\nkernel/sched/ext/internal.h-685-\t * being unloaded or when @cgrp is destroyed. This operation may block.\n--\nkernel/sched/ext/internal.h-704-\t * ops.exit_task() and ops.init_task() instead. @from and @to can\nkernel/sched/ext/internal.h:705:\t * reference cgroups the sched never received ops.cgroup_init() for, as\nkernel/sched/ext/internal.h-706-\t * the cpu controller can be coarser than the sub-scheduler topology.\n--\nkernel/sched/ext/internal.h-745-\t * delivered to @cgrp's parent's sched. That sched may never have seen\nkernel/sched/ext/internal.h:746:\t * ops.cgroup_init() for @cgrp - at a sub-scheduler attach point, the\nkernel/sched/ext/internal.h-747-\t * parent sched tracks @cgrp through ops.sub_attach() instead.\n--\nkernel/sched/ext/internal.h=1046=struct sched_ext_ops_cid {\n--\nkernel/sched/ext/internal.h-1072-#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/internal.h:1073:\ts32 (*cpuctl_init)(struct cgroup *cgrp, struct scx_cgroup_init_args *args);\nkernel/sched/ext/internal.h-1074-\tvoid (*cpuctl_exit)(struct cgroup *cgrp);\n--\nkernel/sched/ext/sub.c=1294=static void scx_fail_parent(struct scx_sched *sch,\n--\nkernel/sched/ext/sub.c-1336- * %SCX_TG_INITED stays set throughout, except for a task_group whose\nkernel/sched/ext/sub.c:1337: * ops.cgroup_init() failed on the parent (see scx_cgroup_return_subtree()):\nkernel/sched/ext/sub.c-1338- * there is nothing to exit from the parent and %SCX_TG_INITED is set back with\n--\nkernel/sched/ext/sub.c=1349=static s32 scx_cgroup_claim_subtree(struct scx_sched *sch)\n--\nkernel/sched/ext/sub.c-1358-\t\tstruct task_group *tg = css_tg(css);\nkernel/sched/ext/sub.c:1359:\t\tstruct scx_cgroup_init_args args = {\nkernel/sched/ext/sub.c-1360-\t\t\t.weight = tg-\u003escx.weight,\n--\nkernel/sched/ext/sub.c-1370-\nkernel/sched/ext/sub.c:1371:\t\tif (SCX_HAS_OP(sch, cgroup_init)) {\nkernel/sched/ext/sub.c:1372:\t\t\tret = SCX_CALL_OP_RET(sch, cgroup_init, NULL, css-\u003ecgroup, \u0026args);\nkernel/sched/ext/sub.c-1373-\t\t\tif (ret) {\nkernel/sched/ext/sub.c:1374:\t\t\t\tscx_error(sch, \"ops.cgroup_init() failed (%d)\", ret);\nkernel/sched/ext/sub.c-1375-\t\t\t\tgoto err;\n--\nkernel/sched/ext/sub.c-1390-\nkernel/sched/ext/sub.c:1391:\t\t/* skip the exit if the parent's ops.cgroup_init() failed */\nkernel/sched/ext/sub.c-1392-\t\tif ((tg-\u003escx.flags \u0026 SCX_TG_INITED) \u0026\u0026 SCX_HAS_OP(parent, cgroup_exit))\n--\nkernel/sched/ext/sub.c-1427- * task re-homing. The remaining task_groups are punted: they move to the parent\nkernel/sched/ext/sub.c:1428: * anyway with %SCX_TG_INITED cleared, as ops.cgroup_init() failed or never ran\nkernel/sched/ext/sub.c-1429- * for them. A punted task_group gets no cgroup ops. The dying parent's own\n--\nkernel/sched/ext/sub.c=1438=static void scx_cgroup_return_subtree(struct scx_sched *sch)\n--\nkernel/sched/ext/sub.c-1453-\nkernel/sched/ext/sub.c:1454:\t\t/* skip the exit if @sch's ops.cgroup_init() failed for the tg */\nkernel/sched/ext/sub.c-1455-\t\tif ((tg-\u003escx.flags \u0026 SCX_TG_INITED) \u0026\u0026 SCX_HAS_OP(sch, cgroup_exit))\n--\nkernel/sched/ext/sub.c-1462-\t\tstruct task_group *tg = css_tg(css);\nkernel/sched/ext/sub.c:1463:\t\tstruct scx_cgroup_init_args args = {\nkernel/sched/ext/sub.c-1464-\t\t\t.weight = tg-\u003escx.weight,\n--\nkernel/sched/ext/sub.c-1490-\nkernel/sched/ext/sub.c:1491:\t\tif (SCX_HAS_OP(parent, cgroup_init)) {\nkernel/sched/ext/sub.c:1492:\t\t\tret = SCX_CALL_OP_RET(parent, cgroup_init, NULL, css-\u003ecgroup, \u0026args);\nkernel/sched/ext/sub.c-1493-\t\t\tif (ret) {\nkernel/sched/ext/sub.c:1494:\t\t\t\tscx_error(parent, \"ops.cgroup_init() failed (%d) while disabling a sub-scheduler\",\nkernel/sched/ext/sub.c-1495-\t\t\t\t\t ret);\n"
} |
| 13/2 | 2026/08/25 03:33 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 20109 output: 30 thoughts: 51 Thoughts: **Examining the Scheduler Extension Configuration** Okay, so it looks like `CONFIG_EXT_GROUP_SCHED` is the crucial configuration option that actually enables the initialization of `cgroup_init` within the scheduler extension (`sched_ext`) framework. Now, to be absolutely sure, and to understand its dependencies and broader implications, I need to dive into the kernel's configuration files. Specifically, I should check the `kernel/sched/Kconfig` file. That's where I'll find the definitions for `EXT_GROUP_SCHED` and hopefully get a clearer picture of how this feature fits into the overall scheduling architecture. Time to dig in and confirm my initial understanding, and potentially uncover some new insights about this section of code. |
| 14/2 | 2026/08/25 03:33 | tool | grepper |
0mArgs:{
"Expression": "EXT_GROUP_SCHED",
"PathPrefix": "kernel/sched/"
}Results: {
"Output": "kernel/sched/core.c=8951=void __init sched_init(void)\n--\nkernel/sched/core.c-8973-#endif /* CONFIG_FAIR_GROUP_SCHED */\nkernel/sched/core.c:8974:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/core.c-8975-\tscx_tg_init(\u0026root_task_group);\nkernel/sched/core.c:8976:#endif /* CONFIG_EXT_GROUP_SCHED */\nkernel/sched/core.c-8977-#ifdef CONFIG_RT_GROUP_SCHED\n--\nkernel/sched/ext/ext.c=3790=static void task_tick_scx(struct rq *rq, struct task_struct *curr, int queued)\n--\nkernel/sched/ext/ext.c-3808-\nkernel/sched/ext/ext.c:3809:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-3810-static struct cgroup *tg_cgrp(struct task_group *tg)\n--\nkernel/sched/ext/ext.c-3824-\nkernel/sched/ext/ext.c:3825:#else\t/* CONFIG_EXT_GROUP_SCHED */\nkernel/sched/ext/ext.c-3826-\n--\nkernel/sched/ext/ext.c-3828-\nkernel/sched/ext/ext.c:3829:#endif\t/* CONFIG_EXT_GROUP_SCHED */\nkernel/sched/ext/ext.c-3830-\n--\nkernel/sched/ext/ext.c=4640=bool scx_can_stop_tick(struct rq *rq)\n--\nkernel/sched/ext/ext.c-4675-\nkernel/sched/ext/ext.c:4676:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-4677-\n--\nkernel/sched/ext/ext.c=4943=void scx_group_set_bandwidth(struct task_group *tg,\n--\nkernel/sched/ext/ext.c-4963-}\nkernel/sched/ext/ext.c:4964:#endif\t/* CONFIG_EXT_GROUP_SCHED */\nkernel/sched/ext/ext.c-4965-\nkernel/sched/ext/ext.c:4966:#if defined(CONFIG_EXT_GROUP_SCHED) || defined(CONFIG_EXT_SUB_SCHED)\nkernel/sched/ext/ext.c-4967-static struct cgroup *root_cgroup(void)\n--\nkernel/sched/ext/ext.c=4977=void scx_cgroup_lock(void)\n--\nkernel/sched/ext/ext.c-4979-\tcgroup_lock();\nkernel/sched/ext/ext.c:4980:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-4981-\tpercpu_down_write(\u0026scx_cgroup_ops_rwsem);\n--\nkernel/sched/ext/ext.c=4985=void scx_cgroup_unlock(void)\nkernel/sched/ext/ext.c-4986-{\nkernel/sched/ext/ext.c:4987:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-4988-\tpercpu_up_write(\u0026scx_cgroup_ops_rwsem);\n--\nkernel/sched/ext/ext.c-4991-}\nkernel/sched/ext/ext.c:4992:#else\t/* CONFIG_EXT_GROUP_SCHED || CONFIG_EXT_SUB_SCHED */\nkernel/sched/ext/ext.c-4993-static inline struct cgroup *root_cgroup(void) { return NULL; }\n--\nkernel/sched/ext/ext.c=4995=static inline void scx_cgroup_unlock(void) {}\nkernel/sched/ext/ext.c:4996:#endif\t/* CONFIG_EXT_GROUP_SCHED || CONFIG_EXT_SUB_SCHED */\nkernel/sched/ext/ext.c-4997-\n--\nkernel/sched/ext/ext.c=5107=static void destroy_dsq(struct scx_sched *sch, u64 dsq_id)\n--\nkernel/sched/ext/ext.c-5145-\nkernel/sched/ext/ext.c:5146:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-5147-static void scx_cgroup_exit(struct scx_sched *sch)\n--\nkernel/sched/ext/ext.c=8072=static int bpf_scx_check_member(const struct btf_type *t,\n--\nkernel/sched/ext/ext.c-8079-\tcase offsetof(struct sched_ext_ops, init_task):\nkernel/sched/ext/ext.c:8080:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-8081-\tcase offsetof(struct sched_ext_ops, cgroup_init):\n--\nkernel/sched/ext/ext.c=8237=static void sched_ext_ops__disable(struct task_struct *p) {}\nkernel/sched/ext/ext.c:8238:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-8239-static s32 sched_ext_ops__cgroup_init(struct cgroup *cgrp, struct scx_cgroup_init_args *args) { return -EINVAL; }\n--\nkernel/sched/ext/ext.c=8246=static void sched_ext_ops__cgroup_set_idle(struct cgroup *cgrp, bool idle) {}\nkernel/sched/ext/ext.c:8247:#endif\t/* CONFIG_EXT_GROUP_SCHED */\nkernel/sched/ext/ext.c-8248-static s32 sched_ext_ops__sub_attach(struct scx_sub_attach_args *args) { return -EINVAL; }\n--\nkernel/sched/ext/ext.c=8259=static struct sched_ext_ops __bpf_ops_sched_ext_ops = {\n--\nkernel/sched/ext/ext.c-8279-\t.disable\t\t= sched_ext_ops__disable,\nkernel/sched/ext/ext.c:8280:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-8281-\t.cgroup_init\t\t= sched_ext_ops__cgroup_init,\n--\nkernel/sched/ext/ext.c=8326=static struct sched_ext_ops_cid __bpf_ops_sched_ext_ops_cid = {\n--\nkernel/sched/ext/ext.c-8344-\t.disable\t\t= sched_ext_ops__disable,\nkernel/sched/ext/ext.c:8345:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-8346-\t.cpuctl_init\t\t= sched_ext_ops__cgroup_init,\n--\nkernel/sched/ext/ext.c=10783=static const u32 scx_kf_allow_flags[] = {\n--\nkernel/sched/ext/ext.c-10789-\t[SCX_OP_IDX(dump)]\t\t= SCX_KF_ALLOW_UNLOCKED,\nkernel/sched/ext/ext.c:10790:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-10791-\t[SCX_OP_IDX(cgroup_init)]\t= SCX_KF_ALLOW_UNLOCKED,\n--\nkernel/sched/ext/ext.c-10797-\t[SCX_OP_IDX(cgroup_set_idle)]\t= SCX_KF_ALLOW_UNLOCKED,\nkernel/sched/ext/ext.c:10798:#endif\t/* CONFIG_EXT_GROUP_SCHED */\nkernel/sched/ext/ext.c-10799-\t[SCX_OP_IDX(sub_attach)]\t= SCX_KF_ALLOW_UNLOCKED,\n--\nkernel/sched/ext/ext.c=10898=static int __init scx_init(void)\n--\nkernel/sched/ext/ext.c-10953-\tCID_OFFSET_MATCH(dump_cpu, dump_cid);\nkernel/sched/ext/ext.c:10954:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-10955-\tCID_OFFSET_MATCH(cgroup_init, cpuctl_init);\n--\nkernel/sched/ext/ext.c=11051=__initcall(scx_init);\n--\nkernel/sched/ext/ext.c-11061- */\nkernel/sched/ext/ext.c:11062:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.c-11063-DEFINE_SCX_COMPAT_MARKER(cgroup_set_bandwidth_may_sleep);\nkernel/sched/ext/ext.c:11064:#endif\t/* CONFIG_EXT_GROUP_SCHED */\n--\nkernel/sched/ext/ext.h=70=static inline void scx_update_idle(struct rq *rq, bool idle, bool do_notify) {}\n--\nkernel/sched/ext/ext.h-73-#ifdef CONFIG_CGROUP_SCHED\nkernel/sched/ext/ext.h:74:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/ext.h-75-void scx_tg_init(struct task_group *tg);\n--\nkernel/sched/ext/ext.h=83=void scx_group_set_bandwidth(struct task_group *tg, u64 period_us, u64 quota_us, u64 burst_us);\nkernel/sched/ext/ext.h:84:#else\t/* CONFIG_EXT_GROUP_SCHED */\nkernel/sched/ext/ext.h-85-static inline void scx_tg_init(struct task_group *tg) {}\n--\nkernel/sched/ext/ext.h=93=static inline void scx_group_set_bandwidth(struct task_group *tg, u64 period_us, u64 quota_us, u64 burst_us) {}\nkernel/sched/ext/ext.h:94:#endif\t/* CONFIG_EXT_GROUP_SCHED */\nkernel/sched/ext/ext.h-95-#endif\t/* CONFIG_CGROUP_SCHED */\n--\nkernel/sched/ext/internal.h=235=struct scx_init_task_args {\n--\nkernel/sched/ext/internal.h-240-\tbool\t\t\tfork;\nkernel/sched/ext/internal.h:241:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/internal.h-242-\t/* the cgroup the task is joining */\n--\nkernel/sched/ext/internal.h=322=struct sched_ext_ops {\n--\nkernel/sched/ext/internal.h-651-\nkernel/sched/ext/internal.h:652:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/internal.h-653-\t/**\n--\nkernel/sched/ext/internal.h-786-\nkernel/sched/ext/internal.h:787:#endif\t/* CONFIG_EXT_GROUP_SCHED */\nkernel/sched/ext/internal.h-788-\n--\nkernel/sched/ext/internal.h=1046=struct sched_ext_ops_cid {\n--\nkernel/sched/ext/internal.h-1071-\tvoid (*dump_task)(struct scx_dump_ctx *ctx, struct task_struct *p);\nkernel/sched/ext/internal.h:1072:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/internal.h-1073-\ts32 (*cpuctl_init)(struct cgroup *cgrp, struct scx_cgroup_init_args *args);\n--\nkernel/sched/ext/internal.h-1083-\tvoid (*cpuctl_set_idle)(struct cgroup *cgrp, bool idle);\nkernel/sched/ext/internal.h:1084:#endif\t/* CONFIG_EXT_GROUP_SCHED */\nkernel/sched/ext/internal.h-1085-\ts32 (*sub_attach)(struct scx_sub_attach_args *args);\n--\nkernel/sched/ext/internal.h=2079=void scx_disable_and_exit_task(struct scx_sched *sch, struct task_struct *p);\nkernel/sched/ext/internal.h:2080:#if defined(CONFIG_EXT_GROUP_SCHED) || defined(CONFIG_EXT_SUB_SCHED)\nkernel/sched/ext/internal.h-2081-void scx_cgroup_lock(void);\n--\nkernel/sched/ext/sub.c=1294=static void scx_fail_parent(struct scx_sched *sch,\n--\nkernel/sched/ext/sub.c-1320-\nkernel/sched/ext/sub.c:1321:#ifdef CONFIG_EXT_GROUP_SCHED\nkernel/sched/ext/sub.c-1322-/**\n"
} |
| 15/2 | 2026/08/25 03:33 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 23711 output: 31 thoughts: 64 Thoughts: **Kernel Configuration Quandary** Okay, so I'm looking at these kernel configurations, and it's pretty clear we need both `CONFIG_SCHED_CLASS_EXT` and `CONFIG_EXT_GROUP_SCHED`. But hold on, before I just blithely assume I can enable them, I need to make sure I'm not overlooking a dependency. Specifically, I'm fairly certain `CONFIG_EXT_GROUP_SCHED` might hinge on `CONFIG_CGROUP_SCHED`. It’s the usual dance with these settings – you can't always just flip the switch without checking upstream. Better to be safe than sorry, and end up with a kernel that won’t boot or performs unpredictably. Right, let’s go directly to the source. Time to dig into `kernel/sched/Kconfig` and refresh my memory on the dependency hierarchy. Shouldn’t take long to sort this out. |
| 16/2 | 2026/08/25 03:33 | tool | grepper |
0mError:no matches Args: {
"Expression": "config EXT_GROUP_SCHED",
"PathPrefix": "kernel/sched/"
}Results: {
"error": "no matches"
} |
| 17/2 | 2026/08/25 03:33 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 24017 output: 31 thoughts: 10 Thoughts: Here's my take on the thought process, as if it were my own: **Diving into the Kernel Configuration Landscape** Okay, so I need to figure out something related to the kernel's configuration. The natural first step, of course, is to check the `init/Kconfig` file. That's the heart of the initial configuration process. It's where I'll find the definitions for a lot of the core options, especially the ones related to initialization. I'm hoping to get a clearer picture of how a specific aspect is controlled during the boot process. Let's see what gems we can find in there. |
| 18/2 | 2026/08/25 03:33 | tool | grepper |
0mArgs:{
"Expression": "config EXT_GROUP_SCHED",
"PathPrefix": "init/Kconfig"
}Results: {
"Output": "init/Kconfig=1196=config RT_GROUP_SCHED_DEFAULT_DISABLED\n--\ninit/Kconfig-1206-\ninit/Kconfig:1207:config EXT_GROUP_SCHED\ninit/Kconfig-1208-\tbool\n"
} |
| 19/2 | 2026/08/25 03:33 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 24271 output: 33 thoughts: 18 Thoughts: Here's my summary, as though I'm thinking these thoughts: **Examining Kconfig for Kernel Configuration** Okay, let's dive in. I need to get a handle on how this particular aspect of the kernel configuration works. Where does this start? Right, `init/Kconfig` is usually a good bet, especially for core initialization stuff. Let's zero in on around line 1207. That should give me a good entry point to see what's being defined and how these configuration options are linked together within the build system. From there, I can trace dependencies and understand the impact of various settings. This should be a good starting point to reconstruct the logic in my head. |
| 20/2 | 2026/08/25 03:34 | tool | read-file |
0mArgs:{
"File": "init/Kconfig",
"FirstLine": 1190,
"LineCount": 30
}Results: {
"Contents": "1190:\t\t This feature lets you explicitly allocate real CPU bandwidth\n1191:\t\t to task groups. If enabled, it will also make it impossible to\n1192:\t\t schedule realtime tasks for non-root users until you allocate\n1193:\t\t realtime bandwidth for them.\n1194:\t\t See Documentation/scheduler/sched-rt-group.rst for more information.\n1195:\t\n1196:\tconfig RT_GROUP_SCHED_DEFAULT_DISABLED\n1197:\t\tbool \"Require boot parameter to enable group scheduling for SCHED_RR/FIFO\"\n1198:\t\tdepends on RT_GROUP_SCHED\n1199:\t\tdefault n\n1200:\t\thelp\n1201:\t\t When set, the RT group scheduling is disabled by default. The option\n1202:\t\t is in inverted form so that mere RT_GROUP_SCHED enables the group\n1203:\t\t scheduling.\n1204:\t\n1205:\t\t Say N if unsure.\n1206:\t\n1207:\tconfig EXT_GROUP_SCHED\n1208:\t\tbool\n1209:\t\tdepends on SCHED_CLASS_EXT \u0026\u0026 CGROUP_SCHED\n1210:\t\tselect GROUP_SCHED_WEIGHT\n1211:\t\tselect GROUP_SCHED_BANDWIDTH\n1212:\t\tdefault y\n1213:\t\n1214:\tendif #CGROUP_SCHED\n1215:\t\n1216:\tconfig EXT_SUB_SCHED\n1217:\t def_bool y\n1218:\t depends on SCHED_CLASS_EXT \u0026\u0026 CGROUPS\n1219:\t\n"
} |
| 21/2 | 2026/08/25 03:34 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 24908 output: 27 thoughts: 59 Thoughts: Okay, here's the summary, rendered as if it's my own thought process: **Kernel Configuration Dependencies** Alright, so the task at hand requires both `SCHED_CLASS_EXT` and `CGROUP_SCHED` to be enabled. My immediate next step, as always, is to pinpoint where these are defined and where their dependencies are documented. Given my experience, I'll start with the obvious places, checking the `init/Kconfig`, `kernel/Kconfig.preempt`, and `kernel/sched/Kconfig` files. These are the usual suspects when dealing with scheduler-related configuration options, and they'll likely provide the necessary context, dependencies, and any relevant documentation needed to proceed. Let's see what we've got in those Kconfig files. |
| 22/2 | 2026/08/25 03:34 | tool | grepper |
0mArgs:{
"Expression": "config SCHED_CLASS_EXT",
"PathPrefix": ""
}Results: {
"Output": "kernel/Kconfig.preempt=155=config SCHED_CORE\n--\nkernel/Kconfig.preempt-172-\nkernel/Kconfig.preempt:173:config SCHED_CLASS_EXT\nkernel/Kconfig.preempt-174-\tbool \"Extensible Scheduling Class\"\n"
} |
| 23/2 | 2026/08/25 03:34 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 25249 output: 35 thoughts: 20 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: **Diving into Preemption Configuration** Okay, so I need to understand something about preemption within the kernel. Let's start with `kernel/Kconfig.preempt`, specifically around line 173. That area usually holds the core definitions and dependencies for the preemption configuration options. I'm guessing that's where the heart of the matter lies. I'll be looking for the fundamental choices there that drive the behavior: whether it's full preemption, voluntary preemption, or maybe some more nuanced configurations. Time to dig in and see what the authors considered critical in making their decisions. It's probably the basis to see the inter-related impacts in other kernel configuration files, too. |
| 24/2 | 2026/08/25 03:34 | tool | read-file |
0mArgs:{
"File": "kernel/Kconfig.preempt",
"FirstLine": 165,
"LineCount": 20
}Results: {
"Contents": " 165:\t\t Use of this feature includes:\n 166:\t\t - mitigation of some (not all) SMT side channels;\n 167:\t\t - limiting SMT interference to improve determinism and/or performance.\n 168:\t\n 169:\t\t SCHED_CORE is default disabled. When it is enabled and unused,\n 170:\t\t which is the likely usage by Linux distributions, there should\n 171:\t\t be no measurable impact on performance.\n 172:\t\n 173:\tconfig SCHED_CLASS_EXT\n 174:\t\tbool \"Extensible Scheduling Class\"\n 175:\t\tdepends on BPF_SYSCALL \u0026\u0026 BPF_JIT \u0026\u0026 DEBUG_INFO_BTF\n 176:\t\tselect GENERIC_ALLOCATOR\n 177:\t\tselect STACKTRACE if STACKTRACE_SUPPORT\n 178:\t\thelp\n 179:\t\t This option enables a new scheduler class sched_ext (SCX), which\n 180:\t\t allows scheduling policies to be implemented as BPF programs to\n 181:\t\t achieve the following:\n 182:\t\n 183:\t\t - Ease of experimentation and exploration: Enabling rapid\n 184:\t\t iteration of new scheduling policies.\n"
} |
| 25/2 | 2026/08/25 03:34 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 25799 output: 31 thoughts: 37 Thoughts: Okay, here's my interpretation of those thoughts, presented as my own mental process, with the bolded header: **Kernel Configuration Considerations** Alright, let's see, we're at a point where we need to ensure certain kernel functionalities are enabled. The immediate requirements are `SCHED_CLASS_EXT` and `CGROUP_SCHED`. Straightforward enough. Now, where to find the configuration options for `CGROUP_SCHED`? Ah, yes, I recall seeing that in `init/Kconfig`. That's the logical place to start – the initialization configuration files are a good starting point for kernel scheduling and resource management settings, especially if we are dealing with cgroups. Looks like we are on the right track. |
| 26/2 | 2026/08/25 03:34 | tool | grepper |
0mArgs:{
"Expression": "config CGROUP_SCHED",
"PathPrefix": "init/Kconfig"
}Results: {
"Output": "init/Kconfig=1147=config CGROUP_WRITEBACK\n--\ninit/Kconfig-1151-\ninit/Kconfig:1152:menuconfig CGROUP_SCHED\ninit/Kconfig-1153-\tbool \"CPU controller\"\n"
} |
| 27/2 | 2026/08/25 03:34 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 26104 output: 33 thoughts: 29 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience, presented in the first person: **Kernel Configuration Dependencies Check** Alright, so `CGROUP_SCHED` is a menuconfig option. My first thought is always to check the dependencies. I need to understand what other kernel features this relies on. Are there any specific subsystems it's tied to, any other control group options it mandates? Understanding the dependency chain is critical. It avoids a lot of headaches down the line during integration and troubleshooting, ensures I enable all the needed parts, and potentially helps to understand conflicts with other configurations. I'm going to dig into the kconfig structure and the code itself to map out those dependencies. Knowing those links is the foundation for properly configuring the kernel. |
| 28/2 | 2026/08/25 03:34 | tool | read-file |
0mArgs:{
"File": "init/Kconfig",
"FirstLine": 1145,
"LineCount": 20
}Results: {
"Contents": "1145:\t\tSee Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.\n1146:\t\n1147:\tconfig CGROUP_WRITEBACK\n1148:\t\tbool\n1149:\t\tdepends on MEMCG \u0026\u0026 BLK_CGROUP\n1150:\t\tdefault y\n1151:\t\n1152:\tmenuconfig CGROUP_SCHED\n1153:\t\tbool \"CPU controller\"\n1154:\t\tdefault n\n1155:\t\thelp\n1156:\t\t This feature lets CPU scheduler recognize task groups and control CPU\n1157:\t\t bandwidth allocation to such task groups. It uses cgroups to group\n1158:\t\t tasks.\n1159:\t\n1160:\tif CGROUP_SCHED\n1161:\tconfig GROUP_SCHED_WEIGHT\n1162:\t\tdef_bool n\n1163:\t\n1164:\tconfig GROUP_SCHED_BANDWIDTH\n"
} |
| 29/2 | 2026/08/25 03:34 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 26596 output: 30 thoughts: 291 Thoughts: **Fuzzing Target Identification: CGROUP_SCHED** Okay, so I'm looking at this `CGROUP_SCHED` patch. Good, no obvious dependencies – that's a plus for isolation. Config-wise, `SCHED_CLASS_EXT` and `CGROUP_SCHED` are the key flags. The core of this patch seems to be touching `scx_cgroup_init_args`. I see that gets used in `scx_tg_online`, `scx_cgroup_init`, `scx_cgroup_claim_subtree`, and `scx_cgroup_return_subtree`. All of these functions are involved in cgroup initialization and sub-scheduler attachment, which immediately flags them as potential fuzzing targets. Now, which of these are the *best* targets? I need to narrow it down. Let's list those functions out as a basis for fuzzing: `scx_tg_online`, `scx_cgroup_init`, `scx_cgroup_claim_subtree`, `scx_cgroup_return_subtree`, and `scx_group_set_idle`. Now, I need to check whether these are static. That impacts call visibility and fuzzing strategies. Alright, let's see: `scx_tg_online` isn't static, which is good from a call perspective; `scx_group_set_idle` is also non-static, another good sign. `scx_cgroup_init`, `scx_cgroup_claim_subtree`, and `scx_cgroup_return_subtree` are static. So, I have to work around that. Given `scx_tg_online` and `scx_group_set_idle` aren't static, I should now focus on where those are called to get an understanding of the entrypoints. |
| 30/2 | 2026/08/25 03:34 | tool | grepper |
0mArgs:{
"Expression": "scx_tg_online",
"PathPrefix": "kernel/sched/"
}Results: {
"Output": "kernel/sched/core.c=9561=static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)\n--\nkernel/sched/core.c-9566-\nkernel/sched/core.c:9567:\tret = scx_tg_online(tg);\nkernel/sched/core.c-9568-\tif (ret)\n--\nkernel/sched/ext/ext.c=4732=static struct scx_sched *scx_tg_knob_sched(struct task_group *tg)\n--\nkernel/sched/ext/ext.c-4741-\nkernel/sched/ext/ext.c:4742:int scx_tg_online(struct task_group *tg)\nkernel/sched/ext/ext.c-4743-{\n--\nkernel/sched/ext/ext.h=75=void scx_tg_init(struct task_group *tg);\nkernel/sched/ext/ext.h:76:int scx_tg_online(struct task_group *tg);\nkernel/sched/ext/ext.h-77-void scx_tg_offline(struct task_group *tg);\n--\nkernel/sched/ext/ext.h=85=static inline void scx_tg_init(struct task_group *tg) {}\nkernel/sched/ext/ext.h:86:static inline int scx_tg_online(struct task_group *tg) { return 0; }\nkernel/sched/ext/ext.h-87-static inline void scx_tg_offline(struct task_group *tg) {}\n"
} |
| 31/2 | 2026/08/25 03:34 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 27733 output: 32 thoughts: 53 Thoughts: Here's my understanding of the situation, from a kernel-level CPU resource management perspective: **My Current CPU Resource Investigation** Okay, so I'm digging into how CPU resources are managed within the cgroup hierarchy. Specifically, I'm noticing two key functions popping up in my trace: `scx_tg_online` and `scx_group_set_idle`. The first, `scx_tg_online`, is getting called from `cpu_cgroup_css_online`, which immediately tells me it's deeply involved in the CPU controller's cgroup initialization process. That makes sense; when a new cgroup, or a new CPU resource is being brought online, this function must be playing a key part. I'll need to explore that code path to understand how this function helps initialize and activate the CPU resources. Then there's `scx_group_set_idle`. The fact that it's called from `sched_group_set_idle` is really interesting. This points to this function having some role in managing the idle state of scheduler groups, likely related to power management or resource reclamation at the scheduler level, or as a consequence of CPU resource contention. I'll need to examine how the scheduler interacts with this function, as well as the function's implementation itself. It looks like both of these are critical for understanding the mechanics of how we get a workload running on the CPUs of a node. |
| 32/2 | 2026/08/25 03:34 | tool | grepper |
0mArgs:{
"Expression": "scx_group_set_idle",
"PathPrefix": "kernel/sched/"
}Results: {
"Output": "kernel/sched/core.c=10259=static int cpu_idle_write_s64(struct cgroup_subsys_state *css,\n--\nkernel/sched/core.c-10265-\tif (!ret)\nkernel/sched/core.c:10266:\t\tscx_group_set_idle(css_tg(css), idle);\nkernel/sched/core.c-10267-\treturn ret;\n--\nkernel/sched/ext/ext.c=4911=void scx_group_set_weight(struct task_group *tg, unsigned long weight)\n--\nkernel/sched/ext/ext.c-4926-\nkernel/sched/ext/ext.c:4927:void scx_group_set_idle(struct task_group *tg, bool idle)\nkernel/sched/ext/ext.c-4928-{\n--\nkernel/sched/ext/ext.h=81=void scx_group_set_weight(struct task_group *tg, unsigned long cgrp_weight);\nkernel/sched/ext/ext.h:82:void scx_group_set_idle(struct task_group *tg, bool idle);\nkernel/sched/ext/ext.h-83-void scx_group_set_bandwidth(struct task_group *tg, u64 period_us, u64 quota_us, u64 burst_us);\n--\nkernel/sched/ext/ext.h=91=static inline void scx_group_set_weight(struct task_group *tg, unsigned long cgrp_weight) {}\nkernel/sched/ext/ext.h:92:static inline void scx_group_set_idle(struct task_group *tg, bool idle) {}\nkernel/sched/ext/ext.h-93-static inline void scx_group_set_bandwidth(struct task_group *tg, u64 period_us, u64 quota_us, u64 burst_us) {}\n"
} |
| 33/2 | 2026/08/25 03:34 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 28615 output: 142 thoughts: 1500 Thoughts: **Analysis of Potential Fuzzing Targets for the Sched_ext Implementation** Okay, let's break this down. My initial thought process led me down a specific path. I see that `scx_group_set_idle` is called from `cpu_idle_write_s64`, which in turn is the handler for the `cpu.idle` cgroup file. That's a good starting point. I considered functions like `scx_tg_online` and `scx_group_set_idle` as the main focus. However, `scx_cgroup_init` is static but called from `scx_root_enable_workfn`, which is called when a BPF scheduler is loaded. `scx_cgroup_claim_subtree` is also static, called from `scx_sub_enable_workfn`. This makes me think that `scx_tg_online` and `scx_group_set_idle` are still the best candidates due to their direct connection to the cgroup operations. While the `scx_sub_enable_workfn` and `scx_root_enable_workfn` functions are involved in sched_ext, they seem more generic. Now, for configuration, I need to make sure the right features are enabled. I definitely need `SCHED_CLASS_EXT` and `CGROUP_SCHED`. Let me double-check the Kconfig. Yep, `EXT_GROUP_SCHED` is automatically enabled if both `SCHED_CLASS_EXT` and `CGROUP_SCHED` are on. Looking at the changes, it seems that the `sched_idle` state is now exposed to the BPF scheduler during initialization in multiple places: `scx_group_set_idle`, `scx_tg_online`, `scx_cgroup_init`, `scx_cgroup_claim_subtree`, and `scx_cgroup_return_subtree`. This makes the state reachable and testable via cgroup operations and BPF sched_ext programs. That seems pretty functional. Okay, this looks solid. I am thinking that this code would benefit from fuzzing. * `WorthFuzzing` is true. * `FocusSymbols`: `scx_tg_online`, `scx_group_set_idle`. * `EnableConfigs`: `SCHED_CLASS_EXT`, `CGROUP_SCHED`. I'm ready to move forward. |
| 34/2 | 2026/08/25 03:34 | tool | set-results |
0mArgs:{
"EnableConfigs": [
"SCHED_CLASS_EXT",
"CGROUP_SCHED"
],
"FocusSymbols": [
"scx_tg_online",
"scx_group_set_idle"
],
"Reasoning": "The patch modifies the sched_ext subsystem to pass the `sched_idle` state of a cgroup to the BPF scheduler during cgroup initialization (`ops.cgroup_init()`). This is a functional change that exposes new data to BPF programs and is reachable via cgroup creation and `cpu.idle` modification while a sched_ext scheduler is active.",
"WorthFuzzing": true
}Results: {
"EnableConfigs": [
"SCHED_CLASS_EXT",
"CGROUP_SCHED"
],
"FocusSymbols": [
"scx_tg_online",
"scx_group_set_idle"
],
"Reasoning": "The patch modifies the sched_ext subsystem to pass the `sched_idle` state of a cgroup to the BPF scheduler during cgroup initialization (`ops.cgroup_init()`). This is a functional change that exposes new data to BPF programs and is reachable via cgroup creation and `cpu.idle` modification while a sched_ext scheduler is active.",
"WorthFuzzing": true
} |
| 35/1 | 2026/08/25 03:34 | action | If |
0mArgs:{
"WorthFuzzing": true
}Results: null |
| 36/2 | 2026/08/25 03:34 | agent | kmsan-evaluator |
0mModel:best-expensive Args: null Results: {
"KMSANReasoning": "The patch renames `idle` to `sched_idle` in `struct scx_task_group` and adds `sched_idle` to `struct scx_cgroup_init_args`. It initializes this new field in several places using designated initializers (e.g., `struct scx_cgroup_init_args args = { ... }`). In C, designated initializers zero out any uninitialized fields and padding bytes. Furthermore, `struct scx_cgroup_init_args` is passed to a BPF program (kernel space), not directly copied to user space. There is no risk of uninitialized memory use or info-leaks introduced by this patch. Standard KASAN and other bug detectors are sufficient to catch any potential memory corruption or out-of-bounds accesses.",
"NeedsKMSAN": false
}Instruction: You are an expert Linux kernel security engineer specializing in kernel memory
error detectors (KASAN and KMSAN). Your job is to review the provided patch series and
determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer)
fuzzing session in addition to standard KASAN fuzzing.
CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN:
- Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable
a comprehensive suite of debugging tools and sanitizers, including KASAN
(out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP
(locking bugs and deadlocks), UB-sanitizers, and memory corruption checks.
- KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap,
or page allocations) and kernel-to-user memory info-leaks.
Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN,
LOCKDEP, OR OTHER STANDARD BUG DETECTORS.
A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY
set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks
that are detected ONLY by KMSAN.
Look holistically at the patch series and surrounding code. Even if no direct
uninitialized field accesses or new buffer allocations are added in the diff itself,
a patch may alter control flow, bounds checking, or data length calculations in ways
that change how the rest of the code operates on existing buffers (e.g. allowing
uninitialized stack/heap memory to be read, copied to user space, or used in control
flow). Do not hesitate to use your code access tools to inspect the surrounding code,
called functions, and callers.
Set NeedsKMSAN=true ONLY IF the patch introduces or modifies:
1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb
attributes, ioctl output arguments, socket options, or BPF buffers) where fields
or structure padding might not be fully initialized/zeroed.
2. Conditional logic or branching that depends on potentially uninitialized variables
or struct fields.
3. Allocation or initialization of complex data structures where uninitialized fields
could be read later in reachable code paths.
4. Bounds checks, lengths, or logic in a way that allows surrounding code to access
uninitialized bytes of existing buffers.
Set NeedsKMSAN=false IF:
- The code changes primarily risk out-of-bounds access, array overflows, NULL pointer
dereferences, locking deadlocks, or use-after-free bugs (these are already caught
by KASAN, LOCKDEP, or standard bug detectors).
- All stack/heap structures touched or introduced by the patch are fully zeroed
or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied.
- The patch does not introduce any risk of uninitialized memory usage or info-leaks.
Use your code access tools to inspect the surrounding code if necessary, then provide
detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch.
Prefer calling several tools at the same time to save round-trips.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt: For your convenience, here is the diff of the changes:
commit 3673dd47de278af3efbec49c7cbc842d047d7302
Author: syz-cluster <triage@syzkaller.com>
Date: Tue Aug 25 03:33:09 2026 +0000
syz-cluster: applied patch under review
diff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h
index 582d7cd4a9839..7b9cdb65deef6 100644
--- a/include/linux/sched/ext.h
+++ b/include/linux/sched/ext.h
@@ -323,7 +323,7 @@ struct scx_task_group {
u64 bw_period_us;
u64 bw_quota_us;
u64 bw_burst_us;
- bool idle;
+ bool sched_idle;
#endif
};
diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c
index c539d15cda637..4a9c382970935 100644
--- a/kernel/sched/ext/ext.c
+++ b/kernel/sched/ext/ext.c
@@ -4682,7 +4682,7 @@ void scx_tg_init(struct task_group *tg)
tg->scx.weight = CGROUP_WEIGHT_DFL;
tg->scx.bw_period_us = default_bw_period_us();
tg->scx.bw_quota_us = RUNTIME_INF;
- tg->scx.idle = false;
+ tg->scx.sched_idle = false;
}
/**
@@ -4764,7 +4764,8 @@ int scx_tg_online(struct task_group *tg)
{ .weight = tg->scx.weight,
.bw_period_us = tg->scx.bw_period_us,
.bw_quota_us = tg->scx.bw_quota_us,
- .bw_burst_us = tg->scx.bw_burst_us };
+ .bw_burst_us = tg->scx.bw_burst_us,
+ .sched_idle = tg->scx.sched_idle };
ret = SCX_CALL_OP_RET(sch, cgroup_init,
NULL, tg->css.cgroup, &args);
@@ -4934,7 +4935,7 @@ void scx_group_set_idle(struct task_group *tg, bool idle)
SCX_CALL_OP(sch, cgroup_set_idle, NULL, tg_cgrp(tg), idle);
/* Update the task group's idle state */
- tg->scx.idle = idle;
+ tg->scx.sched_idle = idle;
percpu_up_read(&scx_cgroup_ops_rwsem);
}
@@ -5185,6 +5186,7 @@ static int scx_cgroup_init(struct scx_sched *sch)
.bw_period_us = tg->scx.bw_period_us,
.bw_quota_us = tg->scx.bw_quota_us,
.bw_burst_us = tg->scx.bw_burst_us,
+ .sched_idle = tg->scx.sched_idle,
};
ret = SCX_CALL_OP_RET(sch, cgroup_init, NULL, css->cgroup, &args);
diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h
index 53e136a47924d..c6987a3a073bf 100644
--- a/kernel/sched/ext/internal.h
+++ b/kernel/sched/ext/internal.h
@@ -259,6 +259,9 @@ struct scx_cgroup_init_args {
u64 bw_period_us;
u64 bw_quota_us;
u64 bw_burst_us;
+
+ /* whether the cgroup is configured SCHED_IDLE via cpu.idle */
+ bool sched_idle;
};
enum scx_cpu_preempt_reason {
diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c
index 0554448835bd0..a17d84db93bdd 100644
--- a/kernel/sched/ext/sub.c
+++ b/kernel/sched/ext/sub.c
@@ -1361,6 +1361,7 @@ static s32 scx_cgroup_claim_subtree(struct scx_sched *sch)
.bw_period_us = tg->scx.bw_period_us,
.bw_quota_us = tg->scx.bw_quota_us,
.bw_burst_us = tg->scx.bw_burst_us,
+ .sched_idle = tg->scx.sched_idle,
};
if (tg->scx.sched != parent ||
@@ -1464,6 +1465,7 @@ static void scx_cgroup_return_subtree(struct scx_sched *sch)
.bw_period_us = tg->scx.bw_period_us,
.bw_quota_us = tg->scx.bw_quota_us,
.bw_burst_us = tg->scx.bw_burst_us,
+ .sched_idle = tg->scx.sched_idle,
};
/* the first pass must have transferred everything */
|
| 37/3 | 2026/08/25 03:34 | llm | kmsan-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 3189 output: 194 thoughts: 1971 Thoughts: **Analysis of the Patch: sched_idle Introduction and Potential Uninitialized Memory** Okay, so this patch is changing `idle` to `sched_idle` within the `scx_task_group` structure. More importantly, it's adding `sched_idle` to `struct scx_cgroup_init_args`. My immediate thought is, "Okay, are we opening ourselves up to uninitialized memory access here?" I need to confirm if padding exists within `struct scx_cgroup_init_args`, and whether this struct is somehow exposed to BPF or, worse, to user-space. Let's look at the structure definition. Right, `weight` (u32), then `bw_period_us` (u64), so there's a 4-byte padding after `weight`. After `bw_period_us`, `bw_quota_us`, and `bw_burst_us` (all u64s), we have `bool sched_idle` which is 1 byte, so there's 7 bytes of padding at the end of this structure. Now, how is `struct scx_cgroup_init_args` used? Ah, it's passed to `cgroup_init` BPF operation. Since `args` is being passed to BPF, which runs in kernel space, it can potentially read those padding bytes. But wait, BPF runs in kernel, so an uninitialized read *shouldn't* cause a user-space information leak, it's just an uninitialized memory read which KMSAN should detect. However, if a BPF program reads padding bytes, it would be an issue because the BPF verifier wouldn't know about the padding unless it's explicitly defined. I need to be sure that `args` is fully initialized, let's look at the usage: it's initialized using a designated initializer. This means uninitialized fields and padding bytes are zeroed, which is exactly what we want. But, is that guaranteed? I'm sure it's zeroed, but I'll check the C standard and make sure. Okay, C99 6.7.8 Initialization says that if there are fewer initializers than there are members, the remainder is initialized like static storage, and with static storage, "any padding is initialized to zero bytes." So, even if this patch *did* introduce new uninitialized memory issues, the use of designated initializers here should ensure that any padding is zeroed. Let's re-examine the patch. The patch *adds* `sched_idle` to `struct scx_cgroup_init_args`, so it is zero-initialized by the compiler automatically. But, just to be thorough, I'll go through all of the places where this structure is used to verify that this is indeed the case. All instances use designated initializers. No, the structure is *fully* initialized. Furthermore, since `args` is used only within kernel space, any read within that space wouldn't be an issue. There is no KMSAN specific bug here. KASAN wouldn't catch uninitialized memory, but there is no uninitialized memory anyway. This patch is safe. Let's double-check the copy-to-user situation, though. BPF programs are kernel-space. They can *read* this struct, but it's not directly copied to user-space. So, no information leak possible. Therefore, this patch is just adding a fully initialized field to a struct and passing it to BPF, and there is no uninitialized memory risk. I'll set NeedsKMSAN to false. |
| 38/3 | 2026/08/25 03:35 | tool | set-results |
0mArgs:{
"KMSANReasoning": "The patch renames `idle` to `sched_idle` in `struct scx_task_group` and adds `sched_idle` to `struct scx_cgroup_init_args`. It initializes this new field in several places using designated initializers (e.g., `struct scx_cgroup_init_args args = { ... }`). In C, designated initializers zero out any uninitialized fields and padding bytes. Furthermore, `struct scx_cgroup_init_args` is passed to a BPF program (kernel space), not directly copied to user space. There is no risk of uninitialized memory use or info-leaks introduced by this patch. Standard KASAN and other bug detectors are sufficient to catch any potential memory corruption or out-of-bounds accesses.",
"NeedsKMSAN": false
}Results: {
"KMSANReasoning": "The patch renames `idle` to `sched_idle` in `struct scx_task_group` and adds `sched_idle` to `struct scx_cgroup_init_args`. It initializes this new field in several places using designated initializers (e.g., `struct scx_cgroup_init_args args = { ... }`). In C, designated initializers zero out any uninitialized fields and padding bytes. Furthermore, `struct scx_cgroup_init_args` is passed to a BPF program (kernel space), not directly copied to user space. There is no risk of uninitialized memory use or info-leaks introduced by this patch. Standard KASAN and other bug detectors are sufficient to catch any potential memory corruption or out-of-bounds accesses.",
"NeedsKMSAN": false
} |
| Total Calls | Total Tokens | Avg Tokens | Total Duration (Seconds) | Avg Duration (Seconds) |
|---|
| Total Calls | Total Duration (Seconds) | Avg Duration (Seconds) |
|---|