AI Trajectory


Trajectory: (Expand/Collapse All)
Seq Timestamp Type Name Duration
0/0 2026/07/24 00:09 flow patch-triage
0m Args: 
null

Results: 
{
  "EnableConfigs": [
    "PAGE_REPORTING"
  ],
  "FocusSymbols": [
    "__page_reporting_request",
    "page_reporting_process"
  ],
  "Reasoning": "The patch introduces a new sysctl `vm.page_reporting_delay` to control the delay of free page reporting. This is a functional change that exposes a new configuration knob to userspace and alters the timing of the page reporting workqueue.",
  "WorthFuzzing": true
}
1/1 2026/07/24 00:09 action read-patch-diff
0m Args: 
null

Results: 
{
  "PatchDiff": "commit 99de9b523eaeabe203b7b095a56403e2c8dbcb31\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Fri Jul 24 00:09:01 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst\nindex b9b0c218bfb440..6efa460b45475a 100644\n--- a/Documentation/admin-guide/sysctl/vm.rst\n+++ b/Documentation/admin-guide/sysctl/vm.rst\n@@ -66,6 +66,7 @@ Currently, these files are in /proc/sys/vm:\n - overcommit_ratio\n - page-cluster\n - page_lock_unfairness\n+- page_reporting_delay\n - panic_on_oom\n - percpu_pagelist_high_fraction\n - stat_interval\n@@ -896,6 +897,18 @@ stolen from under a waiter. After the lock is stolen the number of times\n specified in this file (default is 5), the \"fair lock handoff\" semantics\n will apply, and the waiter will only be awakened if the lock can be taken.\n \n+page_reporting_delay\n+=======================\n+\n+This value determines the delay in milliseconds between free page\n+reporting intervals. A lower delay allows aggressive memory\n+reclamation by returning unused pages to the host quickly, while a\n+higher delay helps to batch free pages over a longer window, absorbing\n+allocation/free churn without hypercall and re-fault overhead.\n+\n+The default value is 2000 (2 seconds). The minimum allowed value is\n+0 (immediate reporting) and the maximum allowed value is 10000 (10 seconds).\n+\n panic_on_oom\n ============\n \ndiff --git a/mm/page_reporting.c b/mm/page_reporting.c\nindex 942e84b6908af7..805da4bc1101a9 100644\n--- a/mm/page_reporting.c\n+++ b/mm/page_reporting.c\n@@ -6,6 +6,7 @@\n #include \u003clinux/export.h\u003e\n #include \u003clinux/module.h\u003e\n #include \u003clinux/delay.h\u003e\n+#include \u003clinux/sysctl.h\u003e\n #include \u003clinux/scatterlist.h\u003e\n \n #include \"page_reporting.h\"\n@@ -47,7 +48,10 @@ MODULE_PARM_DESC(page_reporting_order, \"Set page reporting order\");\n  */\n EXPORT_SYMBOL_GPL(page_reporting_order);\n \n-#define PAGE_REPORTING_DELAY\t(2 * HZ)\n+#define PAGE_REPORTING_DELAY_MS_MAX\t(10 * MSEC_PER_SEC)\n+\n+static unsigned int page_reporting_delay_ms = 2 * MSEC_PER_SEC;\n+static unsigned int page_reporting_delay_ms_max = PAGE_REPORTING_DELAY_MS_MAX;\n static struct page_reporting_dev_info __rcu *pr_dev_info __read_mostly;\n \n enum {\n@@ -56,6 +60,19 @@ enum {\n \tPAGE_REPORTING_ACTIVE\n };\n \n+\n+static struct ctl_table page_reporting_sysctls[] = {\n+\t{\n+\t\t.procname\t= \"page_reporting_delay\",\n+\t\t.data\t\t= \u0026page_reporting_delay_ms,\n+\t\t.maxlen\t\t= sizeof(unsigned int),\n+\t\t.mode\t\t= 0644,\n+\t\t.proc_handler\t= proc_douintvec_minmax,\n+\t\t.extra1\t\t= SYSCTL_ZERO,\n+\t\t.extra2\t\t= \u0026page_reporting_delay_ms_max,\n+\t},\n+};\n+\n /* request page reporting */\n static void\n __page_reporting_request(struct page_reporting_dev_info *prdev)\n@@ -80,7 +97,7 @@ __page_reporting_request(struct page_reporting_dev_info *prdev)\n \t * now we are limiting this to running no more than once every\n \t * couple of seconds.\n \t */\n-\tschedule_delayed_work(\u0026prdev-\u003ework, PAGE_REPORTING_DELAY);\n+\tschedule_delayed_work(\u0026prdev-\u003ework, msecs_to_jiffies(page_reporting_delay_ms));\n }\n \n /* notify prdev of free page reporting request */\n@@ -340,7 +357,7 @@ static void page_reporting_process(struct work_struct *work)\n \t */\n \tstate = atomic_cmpxchg(\u0026prdev-\u003estate, state, PAGE_REPORTING_IDLE);\n \tif (state == PAGE_REPORTING_REQUESTED)\n-\t\tschedule_delayed_work(\u0026prdev-\u003ework, PAGE_REPORTING_DELAY);\n+\t\tschedule_delayed_work(\u0026prdev-\u003ework, msecs_to_jiffies(page_reporting_delay_ms));\n }\n \n static DEFINE_MUTEX(page_reporting_mutex);\n@@ -416,3 +433,10 @@ void page_reporting_unregister(struct page_reporting_dev_info *prdev)\n \tmutex_unlock(\u0026page_reporting_mutex);\n }\n EXPORT_SYMBOL_GPL(page_reporting_unregister);\n+\n+static int __init page_reporting_sysctl_init(void)\n+{\n+\tregister_sysctl_init(\"vm\", page_reporting_sysctls);\n+\treturn 0;\n+}\n+late_initcall(page_reporting_sysctl_init);\n"
}
2/1 2026/07/24 00:09 agent patch-evaluator
0m Model: 
best-expensive

Args: 
null

Results: 
{
  "EnableConfigs": [
    "PAGE_REPORTING"
  ],
  "FocusSymbols": [
    "__page_reporting_request",
    "page_reporting_process"
  ],
  "Reasoning": "The patch introduces a new sysctl `vm.page_reporting_delay` to control the delay of free page reporting. This is a functional change that exposes a new configuration knob to userspace and alters the timing of the page reporting workqueue.",
  "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).

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.
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.
   Do not list too generic configs (we already have them enabled). Only list those that
   specifically cover the modified code. 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 99de9b523eaeabe203b7b095a56403e2c8dbcb31
Author: syz-cluster <triage@syzkaller.com>
Date:   Fri Jul 24 00:09:01 2026 +0000

    syz-cluster: applied patch under review

diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst
index b9b0c218bfb440..6efa460b45475a 100644
--- a/Documentation/admin-guide/sysctl/vm.rst
+++ b/Documentation/admin-guide/sysctl/vm.rst
@@ -66,6 +66,7 @@ Currently, these files are in /proc/sys/vm:
 - overcommit_ratio
 - page-cluster
 - page_lock_unfairness
+- page_reporting_delay
 - panic_on_oom
 - percpu_pagelist_high_fraction
 - stat_interval
@@ -896,6 +897,18 @@ stolen from under a waiter. After the lock is stolen the number of times
 specified in this file (default is 5), the "fair lock handoff" semantics
 will apply, and the waiter will only be awakened if the lock can be taken.
 
+page_reporting_delay
+=======================
+
+This value determines the delay in milliseconds between free page
+reporting intervals. A lower delay allows aggressive memory
+reclamation by returning unused pages to the host quickly, while a
+higher delay helps to batch free pages over a longer window, absorbing
+allocation/free churn without hypercall and re-fault overhead.
+
+The default value is 2000 (2 seconds). The minimum allowed value is
+0 (immediate reporting) and the maximum allowed value is 10000 (10 seconds).
+
 panic_on_oom
 ============
 
diff --git a/mm/page_reporting.c b/mm/page_reporting.c
index 942e84b6908af7..805da4bc1101a9 100644
--- a/mm/page_reporting.c
+++ b/mm/page_reporting.c
@@ -6,6 +6,7 @@
 #include <linux/export.h>
 #include <linux/module.h>
 #include <linux/delay.h>
+#include <linux/sysctl.h>
 #include <linux/scatterlist.h>
 
 #include "page_reporting.h"
@@ -47,7 +48,10 @@ MODULE_PARM_DESC(page_reporting_order, "Set page reporting order");
  */
 EXPORT_SYMBOL_GPL(page_reporting_order);
 
-#define PAGE_REPORTING_DELAY	(2 * HZ)
+#define PAGE_REPORTING_DELAY_MS_MAX	(10 * MSEC_PER_SEC)
+
+static unsigned int page_reporting_delay_ms = 2 * MSEC_PER_SEC;
+static unsigned int page_reporting_delay_ms_max = PAGE_REPORTING_DELAY_MS_MAX;
 static struct page_reporting_dev_info __rcu *pr_dev_info __read_mostly;
 
 enum {
@@ -56,6 +60,19 @@ enum {
 	PAGE_REPORTING_ACTIVE
 };
 
+
+static struct ctl_table page_reporting_sysctls[] = {
+	{
+		.procname	= "page_reporting_delay",
+		.data		= &page_reporting_delay_ms,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_douintvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= &page_reporting_delay_ms_max,
+	},
+};
+
 /* request page reporting */
 static void
 __page_reporting_request(struct page_reporting_dev_info *prdev)
@@ -80,7 +97,7 @@ __page_reporting_request(struct page_reporting_dev_info *prdev)
 	 * now we are limiting this to running no more than once every
 	 * couple of seconds.
 	 */
-	schedule_delayed_work(&prdev->work, PAGE_REPORTING_DELAY);
+	schedule_delayed_work(&prdev->work, msecs_to_jiffies(page_reporting_delay_ms));
 }
 
 /* notify prdev of free page reporting request */
@@ -340,7 +357,7 @@ static void page_reporting_process(struct work_struct *work)
 	 */
 	state = atomic_cmpxchg(&prdev->state, state, PAGE_REPORTING_IDLE);
 	if (state == PAGE_REPORTING_REQUESTED)
-		schedule_delayed_work(&prdev->work, PAGE_REPORTING_DELAY);
+		schedule_delayed_work(&prdev->work, msecs_to_jiffies(page_reporting_delay_ms));
 }
 
 static DEFINE_MUTEX(page_reporting_mutex);
@@ -416,3 +433,10 @@ void page_reporting_unregister(struct page_reporting_dev_info *prdev)
 	mutex_unlock(&page_reporting_mutex);
 }
 EXPORT_SYMBOL_GPL(page_reporting_unregister);
+
+static int __init page_reporting_sysctl_init(void)
+{
+	register_sysctl_init("vm", page_reporting_sysctls);
+	return 0;
+}
+late_initcall(page_reporting_sysctl_init);

3/2 2026/07/24 00:09 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 2998
							output: 28
							thoughts: 188

Thoughts: 
**Assessing the New Page Reporting Delay Configuration**

Okay, so we've got a new patch here. It introduces a `vm.page_reporting_delay` sysctl, which is pretty straightforward: it lets us configure the delay for page reporting. The code updates `mm/page_reporting.c` to use `page_reporting_delay_ms` instead of the current hardcoded constant, and sets up the `page_reporting_sysctls` sysctl table in the initialization function.

Functionally, this is a change because we're adding a new control knob, which is important to consider. My initial instinct is to fuzz this, of course. However, let's step back for a moment and consider the ROI. Is it *really* worth fuzzing? It just modifies a delay and exposes a sysctl. Sysctls are already routinely fuzzed by syzkaller.

Hmm, maybe there's a specific configuration angle? Let's verify. I need to make sure `mm/page_reporting.c` is actually compiled based on `CONFIG_PAGE_REPORTING`. Ok, good. So any fuzzing is in effect, already covered by the larger testing regimen. Let's see if there are any other specific configurations needed.

4/2 2026/07/24 00:09 tool grepper
0m Args: 
{
  "Expression": "CONFIG_PAGE_REPORTING",
  "PathPrefix": "mm/"
}

Results: 
{
  "Output": "mm/Makefile=142=obj-$(CONFIG_PTDUMP) += ptdump.o\nmm/Makefile:143:obj-$(CONFIG_PAGE_REPORTING) += page_reporting.o\nmm/Makefile-144-obj-$(CONFIG_HAVE_BOOTMEM_INFO_NODE) += bootmem_info.o\n--\nmm/page_reporting.h-12-\nmm/page_reporting.h:13:#ifdef CONFIG_PAGE_REPORTING\nmm/page_reporting.h-14-DECLARE_STATIC_KEY_FALSE(page_reporting_enabled);\n--\nmm/page_reporting.h=33=static inline void page_reporting_notify_free(unsigned int order)\n--\nmm/page_reporting.h-45-}\nmm/page_reporting.h:46:#else /* CONFIG_PAGE_REPORTING */\nmm/page_reporting.h-47-#define page_reported(_page)\tfalse\n--\nmm/page_reporting.h=49=static inline void page_reporting_notify_free(unsigned int order)\n--\nmm/page_reporting.h-51-}\nmm/page_reporting.h:52:#endif /* CONFIG_PAGE_REPORTING */\nmm/page_reporting.h-53-#endif /*_MM_PAGE_REPORTING_H */\n"
}
5/2 2026/07/24 00:09 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 3805
							output: 28
							thoughts: 172

Thoughts: 
**Analyzing the `CONFIG_PAGE_REPORTING` Patch**

Okay, so I'm looking at this patch and it seems like the core of it revolves around `CONFIG_PAGE_REPORTING`. Right off the bat, I see the modifications are to `__page_reporting_request`, `page_reporting_process`, and the addition of `page_reporting_sysctl_init`. Nothing too crazy yet, the sysctl is pretty standard.

My immediate thought is: is this worth fuzzing? Considering it's a functional change, the answer is a resounding yes. We need to really test these new interactions. So, let's keep our focus on those primary symbols: `__page_reporting_request`, `page_reporting_process`, and `page_reporting_sysctl_init`.

Wait a minute, `page_reporting_sysctl_init` is an `initcall`. That's important; it's going to execute once at boot. That narrows down where the active work is done - and it looks like `__page_reporting_request` and `page_reporting_process` are the ones utilizing the new sysctl knobs.

Alright, before I dive deeper, let's make sure `CONFIG_PAGE_REPORTING` is the *only* configuration option at play here. Context is everything.

6/2 2026/07/24 00:09 tool grepper
0m Args: 
{
  "Expression": "PAGE_REPORTING",
  "PathPrefix": "mm/Kconfig"
}

Results: 
{
  "Output": "mm/Kconfig=669=config COMPACT_UNEVICTABLE_DEFAULT\n--\nmm/Kconfig-676-# support for free page reporting\nmm/Kconfig:677:config PAGE_REPORTING\nmm/Kconfig-678-\tbool \"Free page reporting\"\n"
}
7/2 2026/07/24 00:09 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 4368
							output: 103
							thoughts: 316

Thoughts: 
**Fuzzing Decision for the PAGE_REPORTING Configuration**

Okay, so the config in question here is `PAGE_REPORTING`. Let's take a look around and see what else we have related to this. I see `__page_reporting_request` and `page_reporting_process`.

Hold on. This seems like a simple sysctl that just controls a delay. It's a small change, but it's a functional change, not just documentation or logging. I initially thought this was a case for returning `WorthFuzzing=true`. Since there are related functions, I was going to include `FocusSymbols=["__page_reporting_request", "page_reporting_process"]` along with `EnableConfigs=["PAGE_REPORTING"]`.

But wait, the prompt... it details criteria for *not* fuzzing. Let me review that. It says to return `WorthFuzzing=false` if the changes are just documentation, Kconfig, comments, decorative logging or tracepoints, numeric constant changes without functional alterations, or unreachable code in virtualized environments.

This patch adds a new sysctl and changes a numeric constant. The original constant was a delay value; the new value is controlled by the sysctl. Does that change the execution flow? It changes the delay of a delayed work, which, although minor, could be significant in certain scenarios. Crucially, it introduces a *new* sysctl, which is accessible and writable from userspace. It's a small change, but it's now directly controllable.

Yes, because it introduces a user-controllable value, I'm going to return `WorthFuzzing=true`.

8/2 2026/07/24 00:09 tool set-results
0m Args: 
{
  "EnableConfigs": [
    "PAGE_REPORTING"
  ],
  "FocusSymbols": [
    "__page_reporting_request",
    "page_reporting_process"
  ],
  "Reasoning": "The patch introduces a new sysctl `vm.page_reporting_delay` to control the delay of free page reporting. This is a functional change that exposes a new configuration knob to userspace and alters the timing of the page reporting workqueue.",
  "WorthFuzzing": true
}

Results: 
{
  "EnableConfigs": [
    "PAGE_REPORTING"
  ],
  "FocusSymbols": [
    "__page_reporting_request",
    "page_reporting_process"
  ],
  "Reasoning": "The patch introduces a new sysctl `vm.page_reporting_delay` to control the delay of free page reporting. This is a functional change that exposes a new configuration knob to userspace and alters the timing of the page reporting workqueue.",
  "WorthFuzzing": true
}
LLM Calls Summary:
Total Calls Total Tokens Avg Tokens Total Duration (Seconds) Avg Duration (Seconds)
Tool Calls Summary:
Total Calls Total Duration (Seconds) Avg Duration (Seconds)