AI Trajectory

null

{
  "EnableConfigs": [
    "POSIX_TIMERS"
  ],
  "FocusSymbols": [
    "begin_new_exec",
    "posix_cpu_timers_exit"
  ],
  "KMSANReasoning": "The patch fixes a bug related to POSIX CPU timers during thread group leadership changes (de_thread). It dequeues the per-thread CPU timers before the thread's PID is handed to the old leader. This prevents issues where the timer subsystem might fail to look up the PID or access freed/invalid structures. The changes involve locking and timer management, which are related to use-after-free, NULL pointer dereferences, or logic bugs. These types of bugs are caught by KASAN or standard kernel debugging tools. The patch does not introduce any new allocations, structures copied to user space, or logic that could expose uninitialized memory, so KMSAN is not applicable here.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch fixes a bug in `de_thread` where POSIX CPU timers are not properly dequeued before `exchange_tids()` hands the thread's PID to the old leader, which can cause a PID lookup failure in `timer_lock_sighand()`. The fix adds a call to `posix_cpu_timers_exit(tsk)` in `de_thread()`. This is a functional change in the core kernel (execve path) and is worth fuzzing.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit 777ec0bdac36a44512a00c64ff491a6d9fa9c342\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Sun Aug 9 02:54:14 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/fs/exec.c b/fs/exec.c\nindex c7b8f2d6366c4..f80f70e1c26de 100644\n--- a/fs/exec.c\n+++ b/fs/exec.c\n@@ -1000,6 +1000,18 @@ static int de_thread(struct task_struct *tsk)\n \t\t * the former thread group leader:\n \t\t */\n \n+#ifdef CONFIG_POSIX_TIMERS\n+\t\t/*\n+\t\t * exchange_tids() hands this thread's PID to the old leader,\n+\t\t * which is reaped right after. The PID lookup in\n+\t\t * timer_lock_sighand() then fails while the per thread CPU\n+\t\t * timers are still queued here, so dequeue them first.\n+\t\t */\n+\t\tspin_lock(lock);\n+\t\tposix_cpu_timers_exit(tsk);\n+\t\tspin_unlock(lock);\n+#endif\n+\n \t\t/* Become a process group leader with the old leader's pid.\n \t\t * The old leader becomes a thread of the this thread group.\n \t\t */\n"
}

best-expensive

null

{
  "EnableConfigs": [
    "POSIX_TIMERS"
  ],
  "FocusSymbols": [
    "begin_new_exec",
    "posix_cpu_timers_exit"
  ],
  "Reasoning": "The patch fixes a bug in `de_thread` where POSIX CPU timers are not properly dequeued before `exchange_tids()` hands the thread's PID to the old leader, which can cause a PID lookup failure in `timer_lock_sighand()`. The fix adds a call to `posix_cpu_timers_exit(tsk)` in `de_thread()`. This is a functional change in the core kernel (execve path) and is worth fuzzing.",
  "WorthFuzzing": true
}

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.

For your convenience, here is the diff of the changes:
commit 777ec0bdac36a44512a00c64ff491a6d9fa9c342
Author: syz-cluster <triage@syzkaller.com>
Date:   Sun Aug 9 02:54:14 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/exec.c b/fs/exec.c
index c7b8f2d6366c4..f80f70e1c26de 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1000,6 +1000,18 @@ static int de_thread(struct task_struct *tsk)
 		 * the former thread group leader:
 		 */
 
+#ifdef CONFIG_POSIX_TIMERS
+		/*
+		 * exchange_tids() hands this thread's PID to the old leader,
+		 * which is reaped right after. The PID lookup in
+		 * timer_lock_sighand() then fails while the per thread CPU
+		 * timers are still queued here, so dequeue them first.
+		 */
+		spin_lock(lock);
+		posix_cpu_timers_exit(tsk);
+		spin_unlock(lock);
+#endif
+
 		/* Become a process group leader with the old leader's pid.
 		 * The old leader becomes a thread of the this thread group.
 		 */

gemini-3.1-pro-preview

null

null

							input: 2055
							output: 33
							thoughts: 163
						

**Analyzing a Kernel Patch: Focus on Fuzzing Potential**

Okay, so there's a patch in `fs/exec.c` that’s altering `de_thread()`. From what I see, the patch introduces a `posix_cpu_timers_exit(tsk)` call *within* `de_thread()` – but only if `CONFIG_POSIX_TIMERS` is enabled. That's immediately interesting, because this is touching the core kernel execution path, specifically when a non-leader thread is calling `execve` and detaching from the thread group. Functionally, it's making a change right there, so my initial instinct is: **definitely** worth fuzzing. The interplay of POSIX timers with the `execve` path could be a rich source of interesting behavior.

Now, let's drill down a bit. What's the context here? Let me check `fs/exec.c` and figure out what "lock" is. Ah, good. It's using `spin_lock(lock);` and `spin_unlock(lock);`, so we're talking about spinlocks. I should check line 1000 in `fs/exec.c` and the lines around it just to get a fuller picture of the lock's scope and the protected data structures. Spinlocks within `de_thread`... this could introduce synchronization issues or race conditions that fuzzing might expose. Gotta look at the bigger picture and how all these puzzle pieces fit together.

{
  "File": "fs/exec.c",
  "FirstLine": 990,
  "LineCount": 30
}

{
  "Contents": " 990:\t\t\t * also take its birthdate (always earlier than our own).\n 991:\t\t\t */\n 992:\t\t\ttsk-\u003estart_time = leader-\u003estart_time;\n 993:\t\t\ttsk-\u003estart_boottime = leader-\u003estart_boottime;\n 994:\t\n 995:\t\t\tBUG_ON(!same_thread_group(leader, tsk));\n 996:\t\t\t/*\n 997:\t\t\t * An exec() starts a new thread group with the\n 998:\t\t\t * TGID of the previous thread group. Rehash the\n 999:\t\t\t * two threads with a switched PID, and release\n1000:\t\t\t * the former thread group leader:\n1001:\t\t\t */\n1002:\t\n1003:\t#ifdef CONFIG_POSIX_TIMERS\n1004:\t\t\t/*\n1005:\t\t\t * exchange_tids() hands this thread's PID to the old leader,\n1006:\t\t\t * which is reaped right after. The PID lookup in\n1007:\t\t\t * timer_lock_sighand() then fails while the per thread CPU\n1008:\t\t\t * timers are still queued here, so dequeue them first.\n1009:\t\t\t */\n1010:\t\t\tspin_lock(lock);\n1011:\t\t\tposix_cpu_timers_exit(tsk);\n1012:\t\t\tspin_unlock(lock);\n1013:\t#endif\n1014:\t\n1015:\t\t\t/* Become a process group leader with the old leader's pid.\n1016:\t\t\t * The old leader becomes a thread of the this thread group.\n1017:\t\t\t */\n1018:\t\t\texchange_tids(tsk, leader);\n1019:\t\t\ttransfer_pid(leader, tsk, PIDTYPE_TGID);\n"
}

gemini-3.1-pro-preview

null

null

							input: 3036
							output: 33
							thoughts: 41
						

Okay, here's my interpretation of that thought process, from an expert's perspective:

**Deconstructing `de_thread`**

Right, so we're looking at `de_thread`, and my immediate thought is to zero in on the locking mechanism. Based on the naming conventions in this codebase, that `lock` variable is almost certainly a spinlock associated with the signal handling structure. Probably something like `&sighand->siglock`, maybe a nested member within a larger structure. Gotta be careful with this, though; signal handling is a minefield. I'll quickly confirm exactly which lock it is. Gotta ensure we're using the correct one, and not accidentally grabbing the wrong lock.

{
  "File": "fs/exec.c",
  "FirstLine": 970,
  "LineCount": 30
}

{
  "Contents": " 970:\t\t\t\t */\n 971:\t\t\t\tsig-\u003enotify_count = -1;\n 972:\t\t\t\tif (likely(leader-\u003eexit_state))\n 973:\t\t\t\t\tbreak;\n 974:\t\t\t\t__set_current_state(TASK_KILLABLE);\n 975:\t\t\t\twrite_unlock_irq(\u0026tasklist_lock);\n 976:\t\t\t\tcgroup_threadgroup_change_end(tsk);\n 977:\t\t\t\tschedule();\n 978:\t\t\t\tif (__fatal_signal_pending(tsk))\n 979:\t\t\t\t\tgoto killed;\n 980:\t\t\t}\n 981:\t\n 982:\t\t\t/*\n 983:\t\t\t * The only record we have of the real-time age of a\n 984:\t\t\t * process, regardless of execs it's done, is start_time.\n 985:\t\t\t * All the past CPU time is accumulated in signal_struct\n 986:\t\t\t * from sister threads now dead.  But in this non-leader\n 987:\t\t\t * exec, nothing survives from the original leader thread,\n 988:\t\t\t * whose birth marks the true age of this process now.\n 989:\t\t\t * When we take on its identity by switching to its PID, we\n 990:\t\t\t * also take its birthdate (always earlier than our own).\n 991:\t\t\t */\n 992:\t\t\ttsk-\u003estart_time = leader-\u003estart_time;\n 993:\t\t\ttsk-\u003estart_boottime = leader-\u003estart_boottime;\n 994:\t\n 995:\t\t\tBUG_ON(!same_thread_group(leader, tsk));\n 996:\t\t\t/*\n 997:\t\t\t * An exec() starts a new thread group with the\n 998:\t\t\t * TGID of the previous thread group. Rehash the\n 999:\t\t\t * two threads with a switched PID, and release\n"
}

gemini-3.1-pro-preview

null

null

							input: 3741
							output: 33
							thoughts: 9
						

Here's my thought process, summarized as you requested:

**Debugging a Missing Definition**

Okay, so I'm looking at this code and hitting a snag. My initial thought is: "Wait, where *is* `lock` defined?" I immediately recognize that something crucial is missing – the context, the declaration, or the scope within which `lock` is supposed to exist. I need to figure out how this `lock` variable or function is supposed to be working, and right now, it's a black box. This is a fundamental first step in understanding the problem, identifying whether it's a straightforward missing import, a more complex scope issue, or perhaps an error in my understanding of the library being used. Time to trace this `lock` to its source.

{
  "File": "fs/exec.c",
  "FirstLine": 940,
  "LineCount": 30
}

{
  "Contents": " 940:\t\n 941:\t\tsig-\u003egroup_exec_task = tsk;\n 942:\t\tsig-\u003enotify_count = zap_other_threads(tsk);\n 943:\t\tif (!thread_group_leader(tsk))\n 944:\t\t\tsig-\u003enotify_count--;\n 945:\t\n 946:\t\twhile (sig-\u003enotify_count) {\n 947:\t\t\t__set_current_state(TASK_KILLABLE);\n 948:\t\t\tspin_unlock_irq(lock);\n 949:\t\t\tschedule();\n 950:\t\t\tif (__fatal_signal_pending(tsk))\n 951:\t\t\t\tgoto killed;\n 952:\t\t\tspin_lock_irq(lock);\n 953:\t\t}\n 954:\t\tspin_unlock_irq(lock);\n 955:\t\n 956:\t\t/*\n 957:\t\t * At this point all other threads have exited, all we have to\n 958:\t\t * do is to wait for the thread group leader to become inactive,\n 959:\t\t * and to assume its PID:\n 960:\t\t */\n 961:\t\tif (!thread_group_leader(tsk)) {\n 962:\t\t\tstruct task_struct *leader = tsk-\u003egroup_leader;\n 963:\t\n 964:\t\t\tfor (;;) {\n 965:\t\t\t\tcgroup_threadgroup_change_begin(tsk);\n 966:\t\t\t\twrite_lock_irq(\u0026tasklist_lock);\n 967:\t\t\t\t/*\n 968:\t\t\t\t * Do this under tasklist_lock to ensure that\n 969:\t\t\t\t * exit_notify() can't miss -\u003egroup_exec_task\n"
}

gemini-3.1-pro-preview

null

null

							input: 4390
							output: 33
							thoughts: 14
						

Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person:

**Navigating Dependencies**

Alright, the code refers to something called `lock`. My immediate instinct is to check for its definition. I'm already thinking about potential scope issues, how it's being used, and what type it is. Is it a mutex? A semaphore? A reader-writer lock? Understanding `lock`'s nature is crucial before I can really grasp what's happening in this section of code and assess its implications for concurrency, resource management, and potential deadlocks. I'm essentially starting with a bottom-up approach here, building my understanding from the foundational element.

{
  "File": "fs/exec.c",
  "FirstLine": 900,
  "LineCount": 40
}

{
  "Contents": " 900:\t\tif (old_mm) {\n 901:\t\t\tmmap_read_unlock(old_mm);\n 902:\t\t\tBUG_ON(active_mm != old_mm);\n 903:\t\t\t/* Defer teardown to setup_new_exec(), outside the exec locks. */\n 904:\t\t\tbprm-\u003eold_mm = old_mm;\n 905:\t\t\treturn 0;\n 906:\t\t}\n 907:\t\tmmdrop_lazy_tlb(active_mm);\n 908:\t\treturn 0;\n 909:\t}\n 910:\t\n 911:\t/* Release the address space replaced by exec, outside the exec locks. */\n 912:\tstatic void exec_mm_put_old(struct mm_struct *old_mm)\n 913:\t{\n 914:\t\tsetmax_mm_hiwater_rss(\u0026current-\u003esignal-\u003emaxrss, old_mm);\n 915:\t\tmm_update_next_owner(old_mm);\n 916:\t\tmmput(old_mm);\n 917:\t}\n 918:\t\n 919:\tstatic int de_thread(struct task_struct *tsk)\n 920:\t{\n 921:\t\tstruct signal_struct *sig = tsk-\u003esignal;\n 922:\t\tstruct sighand_struct *oldsighand = tsk-\u003esighand;\n 923:\t\tspinlock_t *lock = \u0026oldsighand-\u003esiglock;\n 924:\t\n 925:\t\tif (thread_group_empty(tsk))\n 926:\t\t\tgoto no_thread_group;\n 927:\t\n 928:\t\t/*\n 929:\t\t * Kill all other threads in the thread group.\n 930:\t\t */\n 931:\t\tspin_lock_irq(lock);\n 932:\t\tif ((sig-\u003eflags \u0026 SIGNAL_GROUP_EXIT) || sig-\u003egroup_exec_task) {\n 933:\t\t\t/*\n 934:\t\t\t * Another group action in progress, just\n 935:\t\t\t * return so that the signal is processed.\n 936:\t\t\t */\n 937:\t\t\tspin_unlock_irq(lock);\n 938:\t\t\treturn -EAGAIN;\n 939:\t\t}\n"
}

gemini-3.1-pro-preview

null

null

							input: 5188
							output: 34
							thoughts: 180
						

**Analyzing a Potential Race Condition**

Okay, so I'm looking at this patch and immediately, `lock` is defined as `&oldsighand->siglock`. That seems straightforward. But then I see the patch uses `spin_lock(lock);` and later `spin_unlock(lock);`, and something's not quite clicking. `lock` is a pointer to a `spinlock_t`, which is correct. I paused for a moment, thinking I was missing something. No, `spin_lock(lock)` is perfectly valid. My brain caught up, and reminded itself `spin_lock_irq(lock)` is used earlier in the same function. But that still doesn't satisfy me. Is `spin_lock(lock)` safe in *this* specific spot? That's the core question here.

The good news is the patch has already been applied, so at least it compiles without any reported issues. Let's see... this is the `de_thread` function in `fs/exec.c`. Definitely worth adding to my fuzzing list. I need to focus on this `de_thread` function. The problem is, it's declared `static`. Okay, I know my way around a static function, but I need to figure out where it's being called from to gain control. Aha! It's called from `begin_new_exec`. Time to examine that function and see where this rabbit hole leads.

{
  "File": "fs/exec.c",
  "FirstLine": 1050,
  "LineCount": 40
}

{
  "Contents": "1050:\tno_thread_group:\n1051:\t\t/* we have changed execution domain */\n1052:\t\ttsk-\u003eexit_signal = SIGCHLD;\n1053:\t\n1054:\t\tBUG_ON(!thread_group_leader(tsk));\n1055:\t\treturn 0;\n1056:\t\n1057:\tkilled:\n1058:\t\t/* protects against exit_notify() and __exit_signal() */\n1059:\t\tread_lock(\u0026tasklist_lock);\n1060:\t\tsig-\u003egroup_exec_task = NULL;\n1061:\t\tsig-\u003enotify_count = 0;\n1062:\t\tread_unlock(\u0026tasklist_lock);\n1063:\t\treturn -EAGAIN;\n1064:\t}\n1065:\t\n1066:\t\n1067:\t/*\n1068:\t * This function makes sure the current process has its own signal table,\n1069:\t * so that flush_signal_handlers can later reset the handlers without\n1070:\t * disturbing other processes.  (Other processes might share the signal\n1071:\t * table via the CLONE_SIGHAND option to clone().)\n1072:\t */\n1073:\tstatic int unshare_sighand(struct task_struct *me)\n1074:\t{\n1075:\t\tstruct sighand_struct *oldsighand = me-\u003esighand;\n1076:\t\n1077:\t\tif (refcount_read(\u0026oldsighand-\u003ecount) != 1) {\n1078:\t\t\tstruct sighand_struct *newsighand;\n1079:\t\t\t/*\n1080:\t\t\t * This -\u003esighand is shared with the CLONE_SIGHAND\n1081:\t\t\t * but not CLONE_THREAD task, switch to the new one.\n1082:\t\t\t */\n1083:\t\t\tnewsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);\n1084:\t\t\tif (!newsighand)\n1085:\t\t\t\treturn -ENOMEM;\n1086:\t\n1087:\t\t\trefcount_set(\u0026newsighand-\u003ecount, 1);\n1088:\t\n1089:\t\t\twrite_lock_irq(\u0026tasklist_lock);\n"
}

gemini-3.1-pro-preview

null

null

							input: 6309
							output: 28
							thoughts: 12
						

Okay, here's my take on those thoughts, framed as an expert's internal monologue:

**Tracing the Source: Deconstructing the `de_thread` Call**

Alright, so the initial objective is clear: pinpoint the origin of the `de_thread` function call. This isn't just a casual curiosity; identifying the caller is crucial for understanding its purpose within the broader system. I need to know where this thread is being spawned, what triggers its execution, and what information is being passed to it.

My immediate approach will depend heavily on the tools and environment I have available. If I have a debugger handy, I'll set a breakpoint at the entry point of `de_thread` and step backwards through the call stack. This will give me an immediate visual representation of the execution path leading up to it.

If I'm working with source code, I'll start with a straightforward text search within the codebase. Grepping for "de_thread(" or "de_thread(" (depending on the code's syntax) should quickly highlight the direct call sites. I’ll pay close attention to the surrounding context – any conditional statements, variable assignments, or function calls in the vicinity that might provide clues about the purpose and conditions under which `de_thread` is invoked.

Beyond that, I'll need to consider more sophisticated techniques. Is there any cross-referencing functionality in my IDE or code analysis tools? These can often generate a call graph, which will visually map out the relationships between different functions and make it easier to trace the execution flow. I'll be looking for indirect calls as well, maybe a function that takes `de_thread` as an argument or a callback function.

I also have to consider external factors, like threading models or the target operating system. Does this system have a specific thread management framework? Are there any signals, events, or inter-process communication mechanisms that might be involved? These can obfuscate direct calls.

Finally, the function's name hints at a potential "de-" or "delete" operation. Could it be involved in thread termination, cleanup, or resource deallocation? This will influence the types of callsites I expect to see. This information would guide my search. My goal is a full understanding of `de_thread`'s raison d'etre.

{
  "Expression": "de_thread",
  "PathPrefix": "fs/exec.c"
}

{
  "Output": "fs/exec.c=912=static void exec_mm_put_old(struct mm_struct *old_mm)\n--\nfs/exec.c-918-\nfs/exec.c:919:static int de_thread(struct task_struct *tsk)\nfs/exec.c-920-{\n--\nfs/exec.c=1106=void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)\n--\nfs/exec.c-1118- * seen by userspace since either the process is already taking a fatal\nfs/exec.c:1119: * signal (via de_thread() or coredump), or will have SEGV raised\nfs/exec.c-1120- * (after exec_mmap()) by search_binary_handler (see below).\n--\nfs/exec.c=1122=int begin_new_exec(struct linux_binprm * bprm)\n--\nfs/exec.c-1145-\t/* Make this the only thread in the thread group */\nfs/exec.c:1146:\tretval = de_thread(me);\nfs/exec.c-1147-\tif (retval)\n--\nfs/exec.c=1409=static void free_bprm(struct linux_binprm *bprm)\n--\nfs/exec.c-1418-\tif (bprm-\u003ecred) {\nfs/exec.c:1419:\t\t/* in case exec fails before de_thread() succeeds */\nfs/exec.c-1420-\t\tcurrent-\u003efs-\u003ein_exec = 0;\n--\nfs/exec.c=1528=static void check_unsafe_exec(struct linux_binprm *bprm)\n--\nfs/exec.c-1549-\t * Otherwise we set fs-\u003ein_exec = 1 to deny clone(CLONE_FS)\nfs/exec.c:1550:\t * from another sub-thread until de_thread() succeeds, this\nfs/exec.c-1551-\t * state is protected by cred_guard_mutex we hold.\n"
}

gemini-3.1-pro-preview

null

null

							input: 7368
							output: 30
							thoughts: 26
						

Here's my thought process, as requested:

**Tracing the Execution Path**

Okay, so `begin_new_exec` is the one initiating this whole sequence. My immediate instinct is to figure out what function or process is calling *it*. The key here is to understand the origin, the context in which `begin_new_exec` is being invoked. Knowing the caller function is critical for debugging, performance analysis, or simply understanding the overall control flow. We need to trace backwards to understand the initiating action.

{
  "Expression": "begin_new_exec",
  "PathPrefix": "fs/exec.c"
}

{
  "Output": "fs/exec.c=257=static int bprm_mm_init(struct linux_binprm *bprm)\n--\nfs/exec.c-266-\nfs/exec.c:267:\t/* Staged for would_dump() narrowing; consumed by begin_new_exec(). */\nfs/exec.c-268-\tbprm-\u003euser_ns = get_user_ns(current_user_ns());\n--\nfs/exec.c=1106=void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)\n--\nfs/exec.c-1121- */\nfs/exec.c:1122:int begin_new_exec(struct linux_binprm * bprm)\nfs/exec.c-1123-{\n--\nfs/exec.c-1321-}\nfs/exec.c:1322:EXPORT_SYMBOL(begin_new_exec);\nfs/exec.c-1323-\n--\nfs/exec.c=1687=static int search_binary_handler(struct linux_binprm *bprm)\n--\nfs/exec.c-1719-\nfs/exec.c:1720:/* binfmt handlers will call back into begin_new_exec() on success. */\nfs/exec.c-1721-static int exec_binprm(struct linux_binprm *bprm)\n--\nfs/exec.c=1766=static int bprm_execve(struct linux_binprm *bprm)\n--\nfs/exec.c-1775-\t * Check for unsafe execution states before exec_binprm(), which\nfs/exec.c:1776:\t * will call back into begin_new_exec(), into bprm_creds_from_file(),\nfs/exec.c-1777-\t * where setuid-ness is evaluated.\n"
}

gemini-3.1-pro-preview

null

null

							input: 8015
							output: 27
							thoughts: 40
						

Here's a summary of my thought process:

**Tracing the Execution Entry Point**

Okay, so I'm digging into how our executable loading works. The system starts with `begin_new_exec`, which I know is called by the binfmt handlers. But wait a minute... `begin_new_exec` is actually exported? That's interesting, usually functions this low-level aren't. This changes things a bit. So I need to shift gears and find out exactly where this is being called from, given that it is exported. I need to understand the entry points. Let's see how widespread the dependencies are.

{
  "Expression": "begin_new_exec",
  "PathPrefix": "fs/"
}

{
  "Output": "fs/binfmt_elf.c=832=static int load_elf_binary(struct linux_binprm *bprm)\n--\nfs/binfmt_elf.c-1009-\t/* Flush all traces of the currently running executable */\nfs/binfmt_elf.c:1010:\tretval = begin_new_exec(bprm);\nfs/binfmt_elf.c-1011-\tif (retval)\n--\nfs/binfmt_elf_fdpic.c=182=static int load_elf_fdpic_binary(struct linux_binprm *bprm)\n--\nfs/binfmt_elf_fdpic.c-344-\t/* flush all traces of the currently running executable */\nfs/binfmt_elf_fdpic.c:345:\tretval = begin_new_exec(bprm);\nfs/binfmt_elf_fdpic.c-346-\tif (retval)\n--\nfs/binfmt_flat.c=406=static int load_flat_file(struct linux_binprm *bprm,\n--\nfs/binfmt_flat.c-508-\t/* Flush all traces of the currently running executable */\nfs/binfmt_flat.c:509:\tret = begin_new_exec(bprm);\nfs/binfmt_flat.c-510-\tif (ret)\n--\nfs/exec.c=257=static int bprm_mm_init(struct linux_binprm *bprm)\n--\nfs/exec.c-266-\nfs/exec.c:267:\t/* Staged for would_dump() narrowing; consumed by begin_new_exec(). */\nfs/exec.c-268-\tbprm-\u003euser_ns = get_user_ns(current_user_ns());\n--\nfs/exec.c=1106=void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)\n--\nfs/exec.c-1121- */\nfs/exec.c:1122:int begin_new_exec(struct linux_binprm * bprm)\nfs/exec.c-1123-{\n--\nfs/exec.c-1321-}\nfs/exec.c:1322:EXPORT_SYMBOL(begin_new_exec);\nfs/exec.c-1323-\n--\nfs/exec.c=1687=static int search_binary_handler(struct linux_binprm *bprm)\n--\nfs/exec.c-1719-\nfs/exec.c:1720:/* binfmt handlers will call back into begin_new_exec() on success. */\nfs/exec.c-1721-static int exec_binprm(struct linux_binprm *bprm)\n--\nfs/exec.c=1766=static int bprm_execve(struct linux_binprm *bprm)\n--\nfs/exec.c-1775-\t * Check for unsafe execution states before exec_binprm(), which\nfs/exec.c:1776:\t * will call back into begin_new_exec(), into bprm_creds_from_file(),\nfs/exec.c-1777-\t * where setuid-ness is evaluated.\n"
}

gemini-3.1-pro-preview

null

null

							input: 9036
							output: 28
							thoughts: 120
						

**Analyzing the Impact of a Patch on Execve Performance**

Okay, so I'm looking at this patch and tracing its impact. I see that `begin_new_exec` is the critical entry point here, triggered by `load_elf_binary`, `load_elf_fdpic_binary`, and `load_flat_file`. Right, all those are hot paths related to the `execve` system call, making this area a prime target for performance optimization or, in this case, potential regression. The patch specifically touches `de_thread`, which in turn is called by that crucial `begin_new_exec` function. Wait a second, the key change is that it's introducing a call to `posix_cpu_timers_exit(tsk)` within `de_thread`.

The real question is whether this `posix_cpu_timers_exit` function is the right focus of my attention. Is this function an appropriate indicator of performance changes, good or bad, related to this patch? It's worth a deeper dive to understand what this function does and how it interacts with the rest of this code path. Let me go check it out.

{
  "Expression": "posix_cpu_timers_exit",
  "PathPrefix": ""
}

{
  "Output": "fs/exec.c=919=static int de_thread(struct task_struct *tsk)\n--\nfs/exec.c-1010-\t\tspin_lock(lock);\nfs/exec.c:1011:\t\tposix_cpu_timers_exit(tsk);\nfs/exec.c-1012-\t\tspin_unlock(lock);\n--\nfs/exec.c=1122=int begin_new_exec(struct linux_binprm * bprm)\n--\nfs/exec.c-1190-\tspin_lock_irq(\u0026me-\u003esighand-\u003esiglock);\nfs/exec.c:1191:\tposix_cpu_timers_exit(me);\nfs/exec.c-1192-\tspin_unlock_irq(\u0026me-\u003esighand-\u003esiglock);\n--\ninclude/linux/posix-timers.h=225=void run_posix_cpu_timers(void);\ninclude/linux/posix-timers.h:226:void posix_cpu_timers_exit(struct task_struct *task);\ninclude/linux/posix-timers.h:227:void posix_cpu_timers_exit_group(struct task_struct *task);\ninclude/linux/posix-timers.h-228-void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,\n--\nkernel/exit.c=159=static void __exit_signal(struct release_task_post *post, struct task_struct *tsk)\n--\nkernel/exit.c-171-#ifdef CONFIG_POSIX_TIMERS\nkernel/exit.c:172:\tposix_cpu_timers_exit(tsk);\nkernel/exit.c-173-\tif (group_dead)\nkernel/exit.c:174:\t\tposix_cpu_timers_exit_group(tsk);\nkernel/exit.c-175-#endif\n--\nkernel/time/posix-cpu-timers.c=451=static void disarm_timer(struct k_itimer *timer, struct task_struct *p)\n--\nkernel/time/posix-cpu-timers.c-481- *\nkernel/time/posix-cpu-timers.c:482: * __exit_signal() invokes posix_cpu_timers_exit() and if the thread group is\nkernel/time/posix-cpu-timers.c-483- * dead it also invokes posix_cpu_timers_group_exit(). These functions delete\n--\nkernel/time/posix-cpu-timers.c-489- * thread group is not dead they only clean up the per task timers via\nkernel/time/posix-cpu-timers.c:490: * posix_cpu_timers_exit().\nkernel/time/posix-cpu-timers.c-491- *\n--\nkernel/time/posix-cpu-timers.c=624=static void cleanup_timers(struct posix_cputimers *pct)\n--\nkernel/time/posix-cpu-timers.c-633- * is being reaped.  When the final (leader) thread in the group is reaped,\nkernel/time/posix-cpu-timers.c:634: * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.\nkernel/time/posix-cpu-timers.c-635- */\nkernel/time/posix-cpu-timers.c:636:void posix_cpu_timers_exit(struct task_struct *tsk)\nkernel/time/posix-cpu-timers.c-637-{\n--\nkernel/time/posix-cpu-timers.c-639-}\nkernel/time/posix-cpu-timers.c:640:void posix_cpu_timers_exit_group(struct task_struct *tsk)\nkernel/time/posix-cpu-timers.c-641-{\n"
}

gemini-3.1-pro-preview

null

null

							input: 10400
							output: 26
							thoughts: 95
						

**Examining the Thread Exit Routine**

Okay, so `posix_cpu_timers_exit` is a key function, called from multiple places: `__exit_signal`, `begin_new_exec`, and now, importantly, `de_thread`. It seems like a decent point of focus for this problem, but the fact that it's triggered on *every* thread exit is a bit concerning for its specificity. Is there a more refined point of interest within this code path?

Hmm, the bug's connection to `exchange_tids()` and `timer_lock_sighand()` is making me think about where the actual issue might lie. Given that `posix_cpu_timers_exit` seems widespread, maybe the problem is in a function it's calling, like `timer_lock_sighand`. Let's take a closer look at that function and see what it's doing with timers and signal handling.

{
  "Expression": "timer_lock_sighand",
  "PathPrefix": ""
}

{
  "Output": "fs/exec.c=919=static int de_thread(struct task_struct *tsk)\n--\nfs/exec.c-1006-\t\t * which is reaped right after. The PID lookup in\nfs/exec.c:1007:\t\t * timer_lock_sighand() then fails while the per thread CPU\nfs/exec.c-1008-\t\t * timers are still queued here, so dequeue them first.\n--\nkernel/time/posix-cpu-timers.c=451=static void disarm_timer(struct k_itimer *timer, struct task_struct *p)\n--\nkernel/time/posix-cpu-timers.c-522- */\nkernel/time/posix-cpu-timers.c:523:static struct task_struct *timer_lock_sighand(struct k_itimer *timer, unsigned long *flags)\nkernel/time/posix-cpu-timers.c-524-{\n--\nkernel/time/posix-cpu-timers.c=574=static int posix_cpu_timer_del(struct k_itimer *timer)\n--\nkernel/time/posix-cpu-timers.c-579-\nkernel/time/posix-cpu-timers.c:580:\tp = timer_lock_sighand(timer, \u0026flags);\nkernel/time/posix-cpu-timers.c-581-\n--\nkernel/time/posix-cpu-timers.c=706=static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,\n--\nkernel/time/posix-cpu-timers.c-716-\nkernel/time/posix-cpu-timers.c:717:\tp = timer_lock_sighand(timer, \u0026flags);\nkernel/time/posix-cpu-timers.c-718-\t/*\n--\nkernel/time/posix-cpu-timers.c=1082=static bool posix_cpu_timer_rearm(struct k_itimer *timer)\n--\nkernel/time/posix-cpu-timers.c-1088-\nkernel/time/posix-cpu-timers.c:1089:\tp = timer_lock_sighand(timer, \u0026flags);\nkernel/time/posix-cpu-timers.c-1090-\tif (unlikely(!p))\n"
}

gemini-3.1-pro-preview

null

null

							input: 11310
							output: 28
							thoughts: 260
						

**Debugging a Timer-Related Thread PID Issue**

Okay, so here's what I'm dealing with. It looks like `exchange_tids()` is passing a thread's PID to the old leader, and that leader is immediately reaped. The problem arises because later, when `timer_lock_sighand()` tries to look up the PID, it fails while the CPU timers for that specific thread are still queued. We need to dequeue those timers before this lookup happens.

This seems to specifically occur when a non-leader thread executes an `execve` call and has POSIX CPU timers running. To reproduce this, I need to create a thread group with at least two threads. Then, the non-leader thread has to arm a POSIX CPU timer using something like `timer_create` with `CLOCK_THREAD_CPUTIME_ID`. Finally, that non-leader thread needs to execute `execve`.

My initial thought was to check symbols like `posix_cpu_timer_set`, `posix_cpu_timer_del`, and `de_thread`—although `de_thread` is static, so I'll need to look at `begin_new_exec` instead.

But wait, `posix_cpu_timer_set` is also static! Okay, so I need to find the calls to `posix_cpu_timer_set` itself. That's the next step, I need to understand what's *calling* that function. Let's see...

{
  "Expression": "posix_cpu_timer_set",
  "PathPrefix": ""
}

{
  "Output": "kernel/time/posix-cpu-timers.c=451=static void disarm_timer(struct k_itimer *timer, struct task_struct *p)\n--\nkernel/time/posix-cpu-timers.c-513- *\nkernel/time/posix-cpu-timers.c:514: *  - posix_cpu_timer_set(): Independent of the enqueued state that results in a\nkernel/time/posix-cpu-timers.c-515- *    transient failure which is user space visible (-ESRCH) for regular posix\n--\nkernel/time/posix-cpu-timers.c=698=static void __posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp, u64 now);\n--\nkernel/time/posix-cpu-timers.c-705- */\nkernel/time/posix-cpu-timers.c:706:static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,\nkernel/time/posix-cpu-timers.c-707-\t\t\t       struct itimerspec64 *new, struct itimerspec64 *old)\n--\nkernel/time/posix-cpu-timers.c=1537=static int do_cpu_nanosleep(const clockid_t which_clock, int flags,\n--\nkernel/time/posix-cpu-timers.c-1563-\t\tspin_lock_irq(\u0026timer.it_lock);\nkernel/time/posix-cpu-timers.c:1564:\t\terror = posix_cpu_timer_set(\u0026timer, flags, \u0026it, NULL);\nkernel/time/posix-cpu-timers.c-1565-\t\tif (error) {\n--\nkernel/time/posix-cpu-timers.c-1594-\t\texpires = cpu_timer_getexpires(\u0026timer.it.cpu);\nkernel/time/posix-cpu-timers.c:1595:\t\terror = posix_cpu_timer_set(\u0026timer, 0, \u0026zero_it, \u0026it);\nkernel/time/posix-cpu-timers.c-1596-\t\tif (!error) {\n--\nkernel/time/posix-cpu-timers.c=1706=const struct k_clock clock_posix_cpu = {\n--\nkernel/time/posix-cpu-timers.c-1711-\t.nsleep\t\t\t= posix_cpu_nsleep,\nkernel/time/posix-cpu-timers.c:1712:\t.timer_set\t\t= posix_cpu_timer_set,\nkernel/time/posix-cpu-timers.c-1713-\t.timer_del\t\t= posix_cpu_timer_del,\n"
}

gemini-3.1-pro-preview

null

null

							input: 12613
							output: 24
							thoughts: 48
						

Okay, here's my interpretation of that thought process, assuming I'm an expert in systems programming and kernel internals:

**Diving into Timer Implementation**

Alright, so I'm looking at something related to `timer_settime`. My mental map immediately jumps to the fact that this is connected to `clock_posix_cpu`, likely within the context of the `timer_settime` syscall itself, `sys_timer_settime`. I need to understand what's happening. The architecture would dictate my next step, which will be to check `timer_settime`. I need to figure out what functionality this code is serving, so let's dig into that routine. Let's see how it works.

{
  "Expression": "timer_settime",
  "PathPrefix": ""
}

{
  "Output": "Documentation/virt/uml/user_mode_linux_howto_v2.rst=1111=Running ptrace on this thread usually results in the following picture::\n--\nDocumentation/virt/uml/user_mode_linux_howto_v2.rst-1128-   ptrace(PTRACE_GETSIGINFO, 16967, NULL, {si_signo=SIGTRAP, si_code=0x85, si_pid=16967, si_uid=0}) = 0\nDocumentation/virt/uml/user_mode_linux_howto_v2.rst:1129:   timer_settime(0, 0, {it_interval={tv_sec=0, tv_nsec=0}, it_value={tv_sec=0, tv_nsec=2830912}}, NULL) = 0\nDocumentation/virt/uml/user_mode_linux_howto_v2.rst-1130-   getpid()                                = 16566\n--\nDocumentation/virt/uml/user_mode_linux_howto_v2.rst=1135=This is a typical picture from a mostly idle UML instance.\n--\nDocumentation/virt/uml/user_mode_linux_howto_v2.rst-1143-  UML userspace.\nDocumentation/virt/uml/user_mode_linux_howto_v2.rst:1144:* ``timer_settime`` is part of the UML high res timer subsystem mapping\nDocumentation/virt/uml/user_mode_linux_howto_v2.rst-1145-  timer requests from inside UML onto the host high resolution timers.\n--\narch/alpha/kernel/syscalls/syscall.tbl-345-414\tcommon\ttimer_create\t\t\tsys_timer_create\narch/alpha/kernel/syscalls/syscall.tbl:346:415\tcommon\ttimer_settime\t\t\tsys_timer_settime\narch/alpha/kernel/syscalls/syscall.tbl-347-416\tcommon\ttimer_gettime\t\t\tsys_timer_gettime\n--\narch/arm/tools/syscall.tbl-275-257\tcommon\ttimer_create\t\tsys_timer_create\narch/arm/tools/syscall.tbl:276:258\tcommon\ttimer_settime\t\tsys_timer_settime32\narch/arm/tools/syscall.tbl-277-259\tcommon\ttimer_gettime\t\tsys_timer_gettime32\n--\narch/arm/tools/syscall.tbl-426-408\tcommon\ttimer_gettime64\t\t\tsys_timer_gettime\narch/arm/tools/syscall.tbl:427:409\tcommon\ttimer_settime64\t\t\tsys_timer_settime\narch/arm/tools/syscall.tbl-428-410\tcommon\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\narch/arm64/tools/syscall_32.tbl-272-257\tcommon\ttimer_create\t\tsys_timer_create\tcompat_sys_timer_create\narch/arm64/tools/syscall_32.tbl:273:258\tcommon\ttimer_settime\t\tsys_timer_settime32\narch/arm64/tools/syscall_32.tbl-274-259\tcommon\ttimer_gettime\t\tsys_timer_gettime32\n--\narch/arm64/tools/syscall_32.tbl-423-408\tcommon\ttimer_gettime64\t\t\tsys_timer_gettime\narch/arm64/tools/syscall_32.tbl:424:409\tcommon\ttimer_settime64\t\t\tsys_timer_settime\narch/arm64/tools/syscall_32.tbl-425-410\tcommon\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\narch/m68k/kernel/syscalls/syscall.tbl-264-254\tcommon\ttimer_create\t\t\tsys_timer_create\narch/m68k/kernel/syscalls/syscall.tbl:265:255\tcommon\ttimer_settime\t\t\tsys_timer_settime32\narch/m68k/kernel/syscalls/syscall.tbl-266-256\tcommon\ttimer_gettime\t\t\tsys_timer_gettime32\n--\narch/m68k/kernel/syscalls/syscall.tbl-411-408\tcommon\ttimer_gettime64\t\t\tsys_timer_gettime\narch/m68k/kernel/syscalls/syscall.tbl:412:409\tcommon\ttimer_settime64\t\t\tsys_timer_settime\narch/m68k/kernel/syscalls/syscall.tbl-413-410\tcommon\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\narch/microblaze/kernel/syscalls/syscall.tbl-269-259\tcommon\ttimer_create\t\t\tsys_timer_create\narch/microblaze/kernel/syscalls/syscall.tbl:270:260\tcommon\ttimer_settime\t\t\tsys_timer_settime32\narch/microblaze/kernel/syscalls/syscall.tbl-271-261\tcommon\ttimer_gettime\t\t\tsys_timer_gettime32\n--\narch/microblaze/kernel/syscalls/syscall.tbl-417-408\tcommon\ttimer_gettime64\t\t\tsys_timer_gettime\narch/microblaze/kernel/syscalls/syscall.tbl:418:409\tcommon\ttimer_settime64\t\t\tsys_timer_settime\narch/microblaze/kernel/syscalls/syscall.tbl-419-410\tcommon\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\narch/mips/kernel/syscalls/syscall_n32.tbl-231-220\tn32\ttimer_create\t\t\tcompat_sys_timer_create\narch/mips/kernel/syscalls/syscall_n32.tbl:232:221\tn32\ttimer_settime\t\t\tsys_timer_settime32\narch/mips/kernel/syscalls/syscall_n32.tbl-233-222\tn32\ttimer_gettime\t\t\tsys_timer_gettime32\n--\narch/mips/kernel/syscalls/syscall_n32.tbl-350-408\tn32\ttimer_gettime64\t\t\tsys_timer_gettime\narch/mips/kernel/syscalls/syscall_n32.tbl:351:409\tn32\ttimer_settime64\t\t\tsys_timer_settime\narch/mips/kernel/syscalls/syscall_n32.tbl-352-410\tn32\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\narch/mips/kernel/syscalls/syscall_n64.tbl-227-216\tn64\ttimer_create\t\t\tsys_timer_create\narch/mips/kernel/syscalls/syscall_n64.tbl:228:217\tn64\ttimer_settime\t\t\tsys_timer_settime\narch/mips/kernel/syscalls/syscall_n64.tbl-229-218\tn64\ttimer_gettime\t\t\tsys_timer_gettime\n--\narch/mips/kernel/syscalls/syscall_o32.tbl-271-257\to32\ttimer_create\t\t\tsys_timer_create\t\tcompat_sys_timer_create\narch/mips/kernel/syscalls/syscall_o32.tbl:272:258\to32\ttimer_settime\t\t\tsys_timer_settime32\narch/mips/kernel/syscalls/syscall_o32.tbl-273-259\to32\ttimer_gettime\t\t\tsys_timer_gettime32\n--\narch/mips/kernel/syscalls/syscall_o32.tbl-399-408\to32\ttimer_gettime64\t\t\tsys_timer_gettime\t\tsys_timer_gettime\narch/mips/kernel/syscalls/syscall_o32.tbl:400:409\to32\ttimer_settime64\t\t\tsys_timer_settime\t\tsys_timer_settime\narch/mips/kernel/syscalls/syscall_o32.tbl-401-410\to32\ttimerfd_gettime64\t\tsys_timerfd_gettime\t\tsys_timerfd_gettime\n--\narch/parisc/kernel/syscalls/syscall.tbl-279-250\tcommon\ttimer_create\t\tsys_timer_create\t\tcompat_sys_timer_create\narch/parisc/kernel/syscalls/syscall.tbl:280:251\t32\ttimer_settime\t\tsys_timer_settime32\narch/parisc/kernel/syscalls/syscall.tbl:281:251\t64\ttimer_settime\t\tsys_timer_settime\narch/parisc/kernel/syscalls/syscall.tbl-282-252\t32\ttimer_gettime\t\tsys_timer_gettime32\n--\narch/parisc/kernel/syscalls/syscall.tbl-410-408\t32\ttimer_gettime64\t\t\tsys_timer_gettime\t\tsys_timer_gettime\narch/parisc/kernel/syscalls/syscall.tbl:411:409\t32\ttimer_settime64\t\t\tsys_timer_settime\t\tsys_timer_settime\narch/parisc/kernel/syscalls/syscall.tbl-412-410\t32\ttimerfd_gettime64\t\tsys_timerfd_gettime\t\tsys_timerfd_gettime\n--\narch/powerpc/kernel/syscalls/syscall.tbl-306-240\tcommon\ttimer_create\t\t\tsys_timer_create\t\tcompat_sys_timer_create\narch/powerpc/kernel/syscalls/syscall.tbl:307:241\t32\ttimer_settime\t\t\tsys_timer_settime32\narch/powerpc/kernel/syscalls/syscall.tbl:308:241\t64\ttimer_settime\t\t\tsys_timer_settime\narch/powerpc/kernel/syscalls/syscall.tbl:309:241\tspu\ttimer_settime\t\t\tsys_timer_settime\narch/powerpc/kernel/syscalls/syscall.tbl-310-242\t32\ttimer_gettime\t\t\tsys_timer_gettime32\n--\narch/powerpc/kernel/syscalls/syscall.tbl-502-408\t32\ttimer_gettime64\t\t\tsys_timer_gettime\t\tsys_timer_gettime\narch/powerpc/kernel/syscalls/syscall.tbl:503:409\t32\ttimer_settime64\t\t\tsys_timer_settime\t\tsys_timer_settime\narch/powerpc/kernel/syscalls/syscall.tbl-504-410\t32\ttimerfd_gettime64\t\tsys_timerfd_gettime\t\tsys_timerfd_gettime\n--\narch/s390/kernel/syscalls/syscall.tbl-210-254\tcommon\ttimer_create\t\t\tsys_timer_create\narch/s390/kernel/syscalls/syscall.tbl:211:255\tcommon\ttimer_settime\t\t\tsys_timer_settime\narch/s390/kernel/syscalls/syscall.tbl-212-256\tcommon\ttimer_gettime\t\t\tsys_timer_gettime\n--\narch/sh/kernel/syscalls/syscall.tbl-269-259\tcommon\ttimer_create\t\t\tsys_timer_create\narch/sh/kernel/syscalls/syscall.tbl:270:260\tcommon\ttimer_settime\t\t\tsys_timer_settime32\narch/sh/kernel/syscalls/syscall.tbl-271-261\tcommon\ttimer_gettime\t\t\tsys_timer_gettime32\n--\narch/sh/kernel/syscalls/syscall.tbl-415-408\tcommon\ttimer_gettime64\t\t\tsys_timer_gettime\narch/sh/kernel/syscalls/syscall.tbl:416:409\tcommon\ttimer_settime64\t\t\tsys_timer_settime\narch/sh/kernel/syscalls/syscall.tbl-417-410\tcommon\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\narch/sparc/kernel/syscalls/syscall.tbl-318-261\tcommon\tsched_setaffinity\tsys_sched_setaffinity\t\tcompat_sys_sched_setaffinity\narch/sparc/kernel/syscalls/syscall.tbl:319:262\t32\ttimer_settime\t\tsys_timer_settime32\narch/sparc/kernel/syscalls/syscall.tbl:320:262\t64\ttimer_settime\t\tsys_timer_settime\narch/sparc/kernel/syscalls/syscall.tbl-321-263\t32\ttimer_gettime\t\tsys_timer_gettime32\n--\narch/sparc/kernel/syscalls/syscall.tbl-457-408\t32\ttimer_gettime64\t\t\tsys_timer_gettime\t\tsys_timer_gettime\narch/sparc/kernel/syscalls/syscall.tbl:458:409\t32\ttimer_settime64\t\t\tsys_timer_settime\t\tsys_timer_settime\narch/sparc/kernel/syscalls/syscall.tbl-459-410\t32\ttimerfd_gettime64\t\tsys_timerfd_gettime\t\tsys_timerfd_gettime\n--\narch/um/os-Linux/time.c=61=int os_timer_set_interval(int cpu, unsigned long long nsecs)\n--\narch/um/os-Linux/time.c-70-\narch/um/os-Linux/time.c:71:\tif (timer_settime(event_high_res_timer[cpu], 0, \u0026its, NULL) == -1)\narch/um/os-Linux/time.c-72-\t\treturn -errno;\n--\narch/um/os-Linux/time.c=77=int os_timer_one_shot(int cpu, unsigned long long nsecs)\n--\narch/um/os-Linux/time.c-86-\narch/um/os-Linux/time.c:87:\ttimer_settime(event_high_res_timer[cpu], 0, \u0026its, NULL);\narch/um/os-Linux/time.c-88-\treturn 0;\n--\narch/um/os-Linux/time.c=95=void os_timer_disable(int cpu)\n--\narch/um/os-Linux/time.c-99-\tmemset(\u0026its, 0, sizeof(struct itimerspec));\narch/um/os-Linux/time.c:100:\ttimer_settime(event_high_res_timer[cpu], 0, \u0026its, NULL);\narch/um/os-Linux/time.c-101-}\n--\narch/x86/entry/syscalls/syscall_32.tbl-274-259\ti386\ttimer_create\t\tsys_timer_create\t\tcompat_sys_timer_create\narch/x86/entry/syscalls/syscall_32.tbl:275:260\ti386\ttimer_settime\t\tsys_timer_settime32\narch/x86/entry/syscalls/syscall_32.tbl-276-261\ti386\ttimer_gettime\t\tsys_timer_gettime32\n--\narch/x86/entry/syscalls/syscall_32.tbl-417-408\ti386\ttimer_gettime64\t\tsys_timer_gettime\narch/x86/entry/syscalls/syscall_32.tbl:418:409\ti386\ttimer_settime64\t\tsys_timer_settime\narch/x86/entry/syscalls/syscall_32.tbl-419-410\ti386\ttimerfd_gettime64\tsys_timerfd_gettime\n--\narch/x86/entry/syscalls/syscall_64.tbl-234-222\t64\ttimer_create\t\tsys_timer_create\narch/x86/entry/syscalls/syscall_64.tbl:235:223\tcommon\ttimer_settime\t\tsys_timer_settime\narch/x86/entry/syscalls/syscall_64.tbl-236-224\tcommon\ttimer_gettime\t\tsys_timer_gettime\n--\narch/xtensa/kernel/syscalls/syscall.tbl-270-249\tcommon\ttimer_delete\t\t\tsys_timer_delete\narch/xtensa/kernel/syscalls/syscall.tbl:271:250\tcommon\ttimer_settime\t\t\tsys_timer_settime32\narch/xtensa/kernel/syscalls/syscall.tbl-272-251\tcommon\ttimer_gettime\t\t\tsys_timer_gettime32\n--\narch/xtensa/kernel/syscalls/syscall.tbl-382-408\tcommon\ttimer_gettime64\t\t\tsys_timer_gettime\narch/xtensa/kernel/syscalls/syscall.tbl:383:409\tcommon\ttimer_settime64\t\t\tsys_timer_settime\narch/xtensa/kernel/syscalls/syscall.tbl-384-410\tcommon\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\ndrivers/ptp/ptp_netc.c=695=static int netc_timer_gettimex64(struct ptp_clock_info *ptp,\n--\ndrivers/ptp/ptp_netc.c-715-\ndrivers/ptp/ptp_netc.c:716:static int netc_timer_settime64(struct ptp_clock_info *ptp,\ndrivers/ptp/ptp_netc.c-717-\t\t\t\tconst struct timespec64 *ts)\n--\ndrivers/ptp/ptp_netc.c=735=static const struct ptp_clock_info netc_timer_ptp_caps = {\n--\ndrivers/ptp/ptp_netc.c-749-\t.gettimex64\t= netc_timer_gettimex64,\ndrivers/ptp/ptp_netc.c:750:\t.settime64\t= netc_timer_settime64,\ndrivers/ptp/ptp_netc.c-751-\t.enable\t\t= netc_timer_enable,\n--\ninclude/linux/syscalls.h=618=asmlinkage long sys_timer_getoverrun(timer_t timer_id);\ninclude/linux/syscalls.h:619:asmlinkage long sys_timer_settime(timer_t timer_id, int flags,\ninclude/linux/syscalls.h-620-\t\t\t\tconst struct __kernel_itimerspec __user *new_setting,\n--\ninclude/linux/syscalls.h=632=asmlinkage long sys_timer_gettime32(timer_t timer_id,\ninclude/linux/syscalls.h-633-\t\t\t\t struct old_itimerspec32 __user *setting);\ninclude/linux/syscalls.h:634:asmlinkage long sys_timer_settime32(timer_t timer_id, int flags,\ninclude/linux/syscalls.h-635-\t\t\t\t\t struct old_itimerspec32 __user *new,\n--\ninclude/uapi/asm-generic/unistd.h=305=__SYSCALL(__NR_timer_getoverrun, sys_timer_getoverrun)\n--\ninclude/uapi/asm-generic/unistd.h-307-#if defined(__ARCH_WANT_TIME32_SYSCALLS) || __BITS_PER_LONG != 32\ninclude/uapi/asm-generic/unistd.h:308:#define __NR_timer_settime 110\ninclude/uapi/asm-generic/unistd.h:309:__SC_3264(__NR_timer_settime, sys_timer_settime32, sys_timer_settime)\ninclude/uapi/asm-generic/unistd.h-310-#endif\n--\ninclude/uapi/asm-generic/unistd.h=726=__SYSCALL(__NR_timer_gettime64, sys_timer_gettime)\ninclude/uapi/asm-generic/unistd.h:727:#define __NR_timer_settime64 409\ninclude/uapi/asm-generic/unistd.h:728:__SYSCALL(__NR_timer_settime64, sys_timer_settime)\ninclude/uapi/asm-generic/unistd.h-729-#define __NR_timerfd_gettime64 410\n--\ninit/Kconfig=1761=config POSIX_TIMERS\n--\ninit/Kconfig-1770-\t  available: timer_create, timer_gettime: timer_getoverrun,\ninit/Kconfig:1771:\t  timer_settime, timer_delete, clock_adjtime, getitimer,\ninit/Kconfig-1772-\t  setitimer, alarm. Furthermore, the clock_settime, clock_gettime,\n--\nkernel/sys_ni.c=209=COND_SYSCALL(timer_getoverrun);\nkernel/sys_ni.c:210:COND_SYSCALL(timer_settime);\nkernel/sys_ni.c-211-COND_SYSCALL(timer_delete);\n--\nkernel/sys_ni.c=339=COND_SYSCALL_COMPAT(rt_sigtimedwait_time32);\nkernel/sys_ni.c:340:COND_SYSCALL(timer_settime32);\nkernel/sys_ni.c-341-COND_SYSCALL(timer_gettime32);\n--\nkernel/time/posix-cpu-timers.c=698=static void __posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp, u64 now);\n--\nkernel/time/posix-cpu-timers.c-700-/*\nkernel/time/posix-cpu-timers.c:701: * Guts of sys_timer_settime for CPU timers.\nkernel/time/posix-cpu-timers.c-702- * This is called with the timer locked and interrupts disabled.\n--\nkernel/time/posix-timers.c=887=int common_timer_set(struct k_itimer *timr, int flags,\n--\nkernel/time/posix-timers.c-926-\nkernel/time/posix-timers.c:927:static int do_timer_settime(timer_t timer_id, int tmr_flags, struct itimerspec64 *new_spec64,\nkernel/time/posix-timers.c-928-\t\t\t    struct itimerspec64 *old_spec64)\n--\nkernel/time/posix-timers.c-961-/* Set a POSIX.1b interval timer */\nkernel/time/posix-timers.c:962:SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,\nkernel/time/posix-timers.c-963-\t\tconst struct __kernel_itimerspec __user *, new_setting,\n--\nkernel/time/posix-timers.c-975-\trtn = old_setting ? \u0026old_spec : NULL;\nkernel/time/posix-timers.c:976:\terror = do_timer_settime(timer_id, flags, \u0026new_spec, rtn);\nkernel/time/posix-timers.c-977-\tif (!error \u0026\u0026 old_setting) {\n--\nkernel/time/posix-timers.c-984-#ifdef CONFIG_COMPAT_32BIT_TIME\nkernel/time/posix-timers.c:985:SYSCALL_DEFINE4(timer_settime32, timer_t, timer_id, int, flags,\nkernel/time/posix-timers.c-986-\t\tstruct old_itimerspec32 __user *, new,\n--\nkernel/time/posix-timers.c-997-\nkernel/time/posix-timers.c:998:\terror = do_timer_settime(timer_id, flags, \u0026new_spec, rtn);\nkernel/time/posix-timers.c-999-\tif (!error \u0026\u0026 old) {\n--\nscripts/checksyscalls.sh=18=cat \u003c\u003c EOF\n--\nscripts/checksyscalls.sh-100-#define __IGNORE_timer_gettime64\nscripts/checksyscalls.sh:101:#define __IGNORE_timer_settime64\nscripts/checksyscalls.sh-102-#define __IGNORE_timerfd_gettime64\n--\nscripts/checksyscalls.sh-133-#define __IGNORE_timer_gettime\nscripts/checksyscalls.sh:134:#define __IGNORE_timer_settime\nscripts/checksyscalls.sh-135-#define __IGNORE_timerfd_gettime\n--\nscripts/syscall.tbl-139-109\tcommon\ttimer_getoverrun\t\tsys_timer_getoverrun\nscripts/syscall.tbl:140:110\ttime32\ttimer_settime\t\t\tsys_timer_settime32\nscripts/syscall.tbl:141:110\t64\ttimer_settime\t\t\tsys_timer_settime\nscripts/syscall.tbl-142-111\tcommon\ttimer_delete\t\t\tsys_timer_delete\n--\nscripts/syscall.tbl-352-408\t32\ttimer_gettime64\t\t\tsys_timer_gettime\nscripts/syscall.tbl:353:409\t32\ttimer_settime64\t\t\tsys_timer_settime\nscripts/syscall.tbl-354-410\t32\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\ntools/include/nolibc/time.h=124=time_t time(time_t *tptr)\n--\ntools/include/nolibc/time.h-139- * int timer_gettime(timer_t timerid, struct itimerspec *curr_value);\ntools/include/nolibc/time.h:140: * int timer_settime(timer_t timerid, int flags, const struct itimerspec *new_value, struct itimerspec *old_value);\ntools/include/nolibc/time.h-141- */\n--\ntools/include/nolibc/time.h=185=static __attribute__((unused))\ntools/include/nolibc/time.h:186:int _sys_timer_settime(timer_t timerid, int flags,\ntools/include/nolibc/time.h-187-\t\t       const struct itimerspec *new_value, struct itimerspec *old_value)\ntools/include/nolibc/time.h-188-{\ntools/include/nolibc/time.h:189:#if defined(__NR_timer_settime64)\ntools/include/nolibc/time.h-190-\t__nolibc_assert_time64_type(new_value-\u003eit_value.tv_sec);\ntools/include/nolibc/time.h:191:\treturn __nolibc_syscall4(__NR_timer_settime64, timerid, flags, new_value, old_value);\ntools/include/nolibc/time.h-192-#else\ntools/include/nolibc/time.h-193-\t__nolibc_assert_native_time64();\ntools/include/nolibc/time.h:194:\treturn __nolibc_syscall4(__NR_timer_settime, timerid, flags, new_value, old_value);\ntools/include/nolibc/time.h-195-#endif\n--\ntools/include/nolibc/time.h=198=static __attribute__((unused))\ntools/include/nolibc/time.h:199:int timer_settime(timer_t timerid, int flags,\ntools/include/nolibc/time.h-200-\t\t  const struct itimerspec *new_value, struct itimerspec *old_value)\ntools/include/nolibc/time.h-201-{\ntools/include/nolibc/time.h:202:\treturn __sysret(_sys_timer_settime(timerid, flags, new_value, old_value));\ntools/include/nolibc/time.h-203-}\n--\ntools/include/uapi/asm-generic/unistd.h=305=__SYSCALL(__NR_timer_getoverrun, sys_timer_getoverrun)\n--\ntools/include/uapi/asm-generic/unistd.h-307-#if defined(__ARCH_WANT_TIME32_SYSCALLS) || __BITS_PER_LONG != 32\ntools/include/uapi/asm-generic/unistd.h:308:#define __NR_timer_settime 110\ntools/include/uapi/asm-generic/unistd.h:309:__SC_3264(__NR_timer_settime, sys_timer_settime32, sys_timer_settime)\ntools/include/uapi/asm-generic/unistd.h-310-#endif\n--\ntools/include/uapi/asm-generic/unistd.h=726=__SYSCALL(__NR_timer_gettime64, sys_timer_gettime)\ntools/include/uapi/asm-generic/unistd.h:727:#define __NR_timer_settime64 409\ntools/include/uapi/asm-generic/unistd.h:728:__SYSCALL(__NR_timer_settime64, sys_timer_settime)\ntools/include/uapi/asm-generic/unistd.h-729-#define __NR_timerfd_gettime64 410\n--\ntools/perf/arch/alpha/entry/syscalls/syscall.tbl-345-414\tcommon\ttimer_create\t\t\tsys_timer_create\ntools/perf/arch/alpha/entry/syscalls/syscall.tbl:346:415\tcommon\ttimer_settime\t\t\tsys_timer_settime\ntools/perf/arch/alpha/entry/syscalls/syscall.tbl-347-416\tcommon\ttimer_gettime\t\t\tsys_timer_gettime\n--\ntools/perf/arch/arm/entry/syscalls/syscall.tbl-275-257\tcommon\ttimer_create\t\tsys_timer_create\ntools/perf/arch/arm/entry/syscalls/syscall.tbl:276:258\tcommon\ttimer_settime\t\tsys_timer_settime32\ntools/perf/arch/arm/entry/syscalls/syscall.tbl-277-259\tcommon\ttimer_gettime\t\tsys_timer_gettime32\n--\ntools/perf/arch/arm/entry/syscalls/syscall.tbl-426-408\tcommon\ttimer_gettime64\t\t\tsys_timer_gettime\ntools/perf/arch/arm/entry/syscalls/syscall.tbl:427:409\tcommon\ttimer_settime64\t\t\tsys_timer_settime\ntools/perf/arch/arm/entry/syscalls/syscall.tbl-428-410\tcommon\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\ntools/perf/arch/arm64/entry/syscalls/syscall_32.tbl-272-257\tcommon\ttimer_create\t\tsys_timer_create\tcompat_sys_timer_create\ntools/perf/arch/arm64/entry/syscalls/syscall_32.tbl:273:258\tcommon\ttimer_settime\t\tsys_timer_settime32\ntools/perf/arch/arm64/entry/syscalls/syscall_32.tbl-274-259\tcommon\ttimer_gettime\t\tsys_timer_gettime32\n--\ntools/perf/arch/arm64/entry/syscalls/syscall_32.tbl-423-408\tcommon\ttimer_gettime64\t\t\tsys_timer_gettime\ntools/perf/arch/arm64/entry/syscalls/syscall_32.tbl:424:409\tcommon\ttimer_settime64\t\t\tsys_timer_settime\ntools/perf/arch/arm64/entry/syscalls/syscall_32.tbl-425-410\tcommon\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\ntools/perf/arch/mips/entry/syscalls/syscall_n64.tbl-227-216\tn64\ttimer_create\t\t\tsys_timer_create\ntools/perf/arch/mips/entry/syscalls/syscall_n64.tbl:228:217\tn64\ttimer_settime\t\t\tsys_timer_settime\ntools/perf/arch/mips/entry/syscalls/syscall_n64.tbl-229-218\tn64\ttimer_gettime\t\t\tsys_timer_gettime\n--\ntools/perf/arch/parisc/entry/syscalls/syscall.tbl-279-250\tcommon\ttimer_create\t\tsys_timer_create\t\tcompat_sys_timer_create\ntools/perf/arch/parisc/entry/syscalls/syscall.tbl:280:251\t32\ttimer_settime\t\tsys_timer_settime32\ntools/perf/arch/parisc/entry/syscalls/syscall.tbl:281:251\t64\ttimer_settime\t\tsys_timer_settime\ntools/perf/arch/parisc/entry/syscalls/syscall.tbl-282-252\t32\ttimer_gettime\t\tsys_timer_gettime32\n--\ntools/perf/arch/parisc/entry/syscalls/syscall.tbl-410-408\t32\ttimer_gettime64\t\t\tsys_timer_gettime\t\tsys_timer_gettime\ntools/perf/arch/parisc/entry/syscalls/syscall.tbl:411:409\t32\ttimer_settime64\t\t\tsys_timer_settime\t\tsys_timer_settime\ntools/perf/arch/parisc/entry/syscalls/syscall.tbl-412-410\t32\ttimerfd_gettime64\t\tsys_timerfd_gettime\t\tsys_timerfd_gettime\n--\ntools/perf/arch/powerpc/entry/syscalls/syscall.tbl-306-240\tcommon\ttimer_create\t\t\tsys_timer_create\t\tcompat_sys_timer_create\ntools/perf/arch/powerpc/entry/syscalls/syscall.tbl:307:241\t32\ttimer_settime\t\t\tsys_timer_settime32\ntools/perf/arch/powerpc/entry/syscalls/syscall.tbl:308:241\t64\ttimer_settime\t\t\tsys_timer_settime\ntools/perf/arch/powerpc/entry/syscalls/syscall.tbl:309:241\tspu\ttimer_settime\t\t\tsys_timer_settime\ntools/perf/arch/powerpc/entry/syscalls/syscall.tbl-310-242\t32\ttimer_gettime\t\t\tsys_timer_gettime32\n--\ntools/perf/arch/powerpc/entry/syscalls/syscall.tbl-502-408\t32\ttimer_gettime64\t\t\tsys_timer_gettime\t\tsys_timer_gettime\ntools/perf/arch/powerpc/entry/syscalls/syscall.tbl:503:409\t32\ttimer_settime64\t\t\tsys_timer_settime\t\tsys_timer_settime\ntools/perf/arch/powerpc/entry/syscalls/syscall.tbl-504-410\t32\ttimerfd_gettime64\t\tsys_timerfd_gettime\t\tsys_timerfd_gettime\n--\ntools/perf/arch/s390/entry/syscalls/syscall.tbl-210-254\tcommon\ttimer_create\t\t\tsys_timer_create\ntools/perf/arch/s390/entry/syscalls/syscall.tbl:211:255\tcommon\ttimer_settime\t\t\tsys_timer_settime\ntools/perf/arch/s390/entry/syscalls/syscall.tbl-212-256\tcommon\ttimer_gettime\t\t\tsys_timer_gettime\n--\ntools/perf/arch/sh/entry/syscalls/syscall.tbl-269-259\tcommon\ttimer_create\t\t\tsys_timer_create\ntools/perf/arch/sh/entry/syscalls/syscall.tbl:270:260\tcommon\ttimer_settime\t\t\tsys_timer_settime32\ntools/perf/arch/sh/entry/syscalls/syscall.tbl-271-261\tcommon\ttimer_gettime\t\t\tsys_timer_gettime32\n--\ntools/perf/arch/sh/entry/syscalls/syscall.tbl-415-408\tcommon\ttimer_gettime64\t\t\tsys_timer_gettime\ntools/perf/arch/sh/entry/syscalls/syscall.tbl:416:409\tcommon\ttimer_settime64\t\t\tsys_timer_settime\ntools/perf/arch/sh/entry/syscalls/syscall.tbl-417-410\tcommon\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\ntools/perf/arch/sparc/entry/syscalls/syscall.tbl-318-261\tcommon\tsched_setaffinity\tsys_sched_setaffinity\t\tcompat_sys_sched_setaffinity\ntools/perf/arch/sparc/entry/syscalls/syscall.tbl:319:262\t32\ttimer_settime\t\tsys_timer_settime32\ntools/perf/arch/sparc/entry/syscalls/syscall.tbl:320:262\t64\ttimer_settime\t\tsys_timer_settime\ntools/perf/arch/sparc/entry/syscalls/syscall.tbl-321-263\t32\ttimer_gettime\t\tsys_timer_gettime32\n--\ntools/perf/arch/sparc/entry/syscalls/syscall.tbl-457-408\t32\ttimer_gettime64\t\t\tsys_timer_gettime\t\tsys_timer_gettime\ntools/perf/arch/sparc/entry/syscalls/syscall.tbl:458:409\t32\ttimer_settime64\t\t\tsys_timer_settime\t\tsys_timer_settime\ntools/perf/arch/sparc/entry/syscalls/syscall.tbl-459-410\t32\ttimerfd_gettime64\t\tsys_timerfd_gettime\t\tsys_timerfd_gettime\n--\ntools/perf/arch/x86/entry/syscalls/syscall_32.tbl-274-259\ti386\ttimer_create\t\tsys_timer_create\t\tcompat_sys_timer_create\ntools/perf/arch/x86/entry/syscalls/syscall_32.tbl:275:260\ti386\ttimer_settime\t\tsys_timer_settime32\ntools/perf/arch/x86/entry/syscalls/syscall_32.tbl-276-261\ti386\ttimer_gettime\t\tsys_timer_gettime32\n--\ntools/perf/arch/x86/entry/syscalls/syscall_32.tbl-417-408\ti386\ttimer_gettime64\t\tsys_timer_gettime\ntools/perf/arch/x86/entry/syscalls/syscall_32.tbl:418:409\ti386\ttimer_settime64\t\tsys_timer_settime\ntools/perf/arch/x86/entry/syscalls/syscall_32.tbl-419-410\ti386\ttimerfd_gettime64\tsys_timerfd_gettime\n--\ntools/perf/arch/x86/entry/syscalls/syscall_64.tbl-234-222\t64\ttimer_create\t\tsys_timer_create\ntools/perf/arch/x86/entry/syscalls/syscall_64.tbl:235:223\tcommon\ttimer_settime\t\tsys_timer_settime\ntools/perf/arch/x86/entry/syscalls/syscall_64.tbl-236-224\tcommon\ttimer_gettime\t\tsys_timer_gettime\n--\ntools/perf/arch/xtensa/entry/syscalls/syscall.tbl-270-249\tcommon\ttimer_delete\t\t\tsys_timer_delete\ntools/perf/arch/xtensa/entry/syscalls/syscall.tbl:271:250\tcommon\ttimer_settime\t\t\tsys_timer_settime32\ntools/perf/arch/xtensa/entry/syscalls/syscall.tbl-272-251\tcommon\ttimer_gettime\t\t\tsys_timer_gettime32\n--\ntools/perf/arch/xtensa/entry/syscalls/syscall.tbl-382-408\tcommon\ttimer_gettime64\t\t\tsys_timer_gettime\ntools/perf/arch/xtensa/entry/syscalls/syscall.tbl:383:409\tcommon\ttimer_settime64\t\t\tsys_timer_settime\ntools/perf/arch/xtensa/entry/syscalls/syscall.tbl-384-410\tcommon\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\ntools/power/x86/turbostat/turbostat.c=6779=void msr_sum_record(void)\n--\ntools/power/x86/turbostat/turbostat.c-6812-\ntools/power/x86/turbostat/turbostat.c:6813:\tif (timer_settime(timerid, 0, \u0026its, NULL) == -1) {\ntools/power/x86/turbostat/turbostat.c-6814-\t\tfprintf(outf, \"Can not set timer.\\n\");\n--\ntools/scripts/syscall.tbl-139-109\tcommon\ttimer_getoverrun\t\tsys_timer_getoverrun\ntools/scripts/syscall.tbl:140:110\ttime32\ttimer_settime\t\t\tsys_timer_settime32\ntools/scripts/syscall.tbl:141:110\t64\ttimer_settime\t\t\tsys_timer_settime\ntools/scripts/syscall.tbl-142-111\tcommon\ttimer_delete\t\t\tsys_timer_delete\n--\ntools/scripts/syscall.tbl-352-408\t32\ttimer_gettime64\t\t\tsys_timer_gettime\ntools/scripts/syscall.tbl:353:409\t32\ttimer_settime64\t\t\tsys_timer_settime\ntools/scripts/syscall.tbl-354-410\t32\ttimerfd_gettime64\t\tsys_timerfd_gettime\n--\ntools/testing/selftests/bpf/test_progs.c=194=static void watchdog_timer_func(union sigval sigval)\n--\ntools/testing/selftests/bpf/test_progs.c-212-\t\tenv.watchdog_state = WD_KILL;\ntools/testing/selftests/bpf/test_progs.c:213:\t\terr = timer_settime(env.watchdog, 0, \u0026timeout, NULL);\ntools/testing/selftests/bpf/test_progs.c-214-\t\tif (err)\n--\ntools/testing/selftests/bpf/test_progs.c=226=static void watchdog_start(void)\n--\ntools/testing/selftests/bpf/test_progs.c-239-\t}\ntools/testing/selftests/bpf/test_progs.c:240:\terr = timer_settime(env.watchdog, 0, \u0026timeout, NULL);\ntools/testing/selftests/bpf/test_progs.c-241-\tif (err)\n--\ntools/testing/selftests/bpf/test_progs.c=245=static void watchdog_stop(void)\n--\ntools/testing/selftests/bpf/test_progs.c-250-\tenv.watchdog_state = WD_NOTIFY;\ntools/testing/selftests/bpf/test_progs.c:251:\terr = timer_settime(env.watchdog, 0, \u0026timeout, NULL);\ntools/testing/selftests/bpf/test_progs.c-252-\tif (err)\n--\ntools/testing/selftests/nolibc/nolibc-test.c=1093=int test_timer(void)\n--\ntools/testing/selftests/nolibc/nolibc-test.c-1108-\t};\ntools/testing/selftests/nolibc/nolibc-test.c:1109:\tret = timer_settime(timer, 0, \u0026timerspec, NULL);\ntools/testing/selftests/nolibc/nolibc-test.c-1110-\tif (ret)\n--\ntools/testing/selftests/timens/timer.c=18=static int run_test(int clockid, struct timespec now)\n--\ntools/testing/selftests/timens/timer.c-51-\t\t\tflags |= TIMER_ABSTIME;\ntools/testing/selftests/timens/timer.c:52:\t\tif (timer_settime(fd, flags, \u0026new_value, NULL) == -1)\ntools/testing/selftests/timens/timer.c-53-\t\t\treturn pr_perror(\"timerfd_settime\");\n--\ntools/testing/selftests/timers/alarmtimer-suspend.c=105=int main(void)\n--\ntools/testing/selftests/timers/alarmtimer-suspend.c-144-\ntools/testing/selftests/timers/alarmtimer-suspend.c:145:\t\ttimer_settime(tm1, TIMER_ABSTIME, \u0026its1, \u0026its2);\ntools/testing/selftests/timers/alarmtimer-suspend.c-146-\n--\ntools/testing/selftests/timers/leap-a-day.c=175=int main(int argc, char **argv)\n--\ntools/testing/selftests/timers/leap-a-day.c-303-\t\tits1.it_interval.tv_nsec = 0;\ntools/testing/selftests/timers/leap-a-day.c:304:\t\ttimer_settime(tm1, TIMER_ABSTIME, \u0026its1, NULL);\ntools/testing/selftests/timers/leap-a-day.c-305-\n--\ntools/testing/selftests/timers/nanosleep.c=124=static int nanosleep_test_remaining(int clockid)\n--\ntools/testing/selftests/timers/nanosleep.c-141-\titimer.it_value.tv_nsec = NSEC_PER_SEC / 4;\ntools/testing/selftests/timers/nanosleep.c:142:\tret = timer_settime(timer, 0, \u0026itimer, NULL);\ntools/testing/selftests/timers/nanosleep.c-143-\tif (ret)\n--\ntools/testing/selftests/timers/posix_timers.c=144=static void check_timer_create(int which, const char *name)\n--\ntools/testing/selftests/timers/posix_timers.c-163-\ntools/testing/selftests/timers/posix_timers.c:164:\tif (timer_settime(id, 0, \u0026val, NULL) \u003c 0)\ntools/testing/selftests/timers/posix_timers.c:165:\t\tfatal_error(name, \"timer_settime()\");\ntools/testing/selftests/timers/posix_timers.c-166-\n--\ntools/testing/selftests/timers/posix_timers.c=186=static void *ctd_thread_func(void *arg)\n--\ntools/testing/selftests/timers/posix_timers.c-201-\t\tfatal_error(NULL, \"timer_create()\");\ntools/testing/selftests/timers/posix_timers.c:202:\tif (timer_settime(id, 0, \u0026val, NULL))\ntools/testing/selftests/timers/posix_timers.c:203:\t\tfatal_error(NULL, \"timer_settime()\");\ntools/testing/selftests/timers/posix_timers.c-204-\twhile (ctd_count \u003e 0 \u0026\u0026 !ctd_failed)\n--\ntools/testing/selftests/timers/posix_timers.c=268=static void check_sig_ign(int thread)\n--\ntools/testing/selftests/timers/posix_timers.c-313-\tits.it_interval.tv_nsec = 100000000;\ntools/testing/selftests/timers/posix_timers.c:314:\ttimer_settime(timerid, 0, \u0026its, NULL);\ntools/testing/selftests/timers/posix_timers.c-315-\n--\ntools/testing/selftests/timers/posix_timers.c=354=static void check_rearm(void)\n--\ntools/testing/selftests/timers/posix_timers.c-386-\tits.it_interval.tv_nsec = 100000000;\ntools/testing/selftests/timers/posix_timers.c:387:\tif (timer_settime(timerid, 0, \u0026its, NULL))\ntools/testing/selftests/timers/posix_timers.c:388:\t\tfatal_error(NULL, \"timer_settime()\");\ntools/testing/selftests/timers/posix_timers.c-389-\n--\ntools/testing/selftests/timers/posix_timers.c-396-\tits.it_interval.tv_nsec = 0;\ntools/testing/selftests/timers/posix_timers.c:397:\tif (timer_settime(timerid, 0, \u0026its, NULL))\ntools/testing/selftests/timers/posix_timers.c:398:\t\tfatal_error(NULL, \"timer_settime()\");\ntools/testing/selftests/timers/posix_timers.c-399-\n--\ntools/testing/selftests/timers/posix_timers.c=410=static void check_delete(void)\n--\ntools/testing/selftests/timers/posix_timers.c-442-\tits.it_interval.tv_nsec = 100000000;\ntools/testing/selftests/timers/posix_timers.c:443:\tif (timer_settime(timerid, 0, \u0026its, NULL))\ntools/testing/selftests/timers/posix_timers.c:444:\t\tfatal_error(NULL, \"timer_settime()\");\ntools/testing/selftests/timers/posix_timers.c-445-\n--\ntools/testing/selftests/timers/posix_timers.c=458=static void check_sigev_none(int which, const char *name)\n--\ntools/testing/selftests/timers/posix_timers.c-475-\tits.it_interval.tv_nsec = 100000000;\ntools/testing/selftests/timers/posix_timers.c:476:\ttimer_settime(timerid, 0, \u0026its, NULL);\ntools/testing/selftests/timers/posix_timers.c-477-\n--\ntools/testing/selftests/timers/posix_timers.c=496=static void check_gettime(int which, const char *name)\n--\ntools/testing/selftests/timers/posix_timers.c-522-\tits.it_interval.tv_nsec = 100000000;\ntools/testing/selftests/timers/posix_timers.c:523:\tif (timer_settime(timerid, 0, \u0026its, NULL))\ntools/testing/selftests/timers/posix_timers.c:524:\t\tfatal_error(name, \"timer_settime()\");\ntools/testing/selftests/timers/posix_timers.c-525-\n--\ntools/testing/selftests/timers/posix_timers.c=549=static void check_overrun(int which, const char *name)\n--\ntools/testing/selftests/timers/posix_timers.c-582-\tits.it_interval.tv_nsec = 100000000;\ntools/testing/selftests/timers/posix_timers.c:583:\tif (timer_settime(timerid, 0, \u0026its, NULL))\ntools/testing/selftests/timers/posix_timers.c:584:\t\tfatal_error(name, \"timer_settime()\");\ntools/testing/selftests/timers/posix_timers.c-585-\n--\ntools/testing/selftests/timers/set-timer-lat.c=111=int setup_timer(int clock_id, int flags, int interval, timer_t *tm1)\n--\ntools/testing/selftests/timers/set-timer-lat.c-151-\ntools/testing/selftests/timers/set-timer-lat.c:152:\terr = timer_settime(*tm1, flags, \u0026its1, \u0026its2);\ntools/testing/selftests/timers/set-timer-lat.c-153-\tif (err) {\ntools/testing/selftests/timers/set-timer-lat.c:154:\t\tprintf(\"%s - timer_settime() failed\\n\", clockstring(clock_id));\ntools/testing/selftests/timers/set-timer-lat.c-155-\t\treturn -1;\n"
}

gemini-3.1-pro-preview

null

null

							input: 26452
							output: 33
							thoughts: 256
						

**Analyzing the Bug's Context**

Okay, so I'm trying to wrap my head around this bug. My initial thought was that `sys_timer_settime` looked like a good starting point, a potential focus symbol, but then I remembered Syzkaller is already hitting syscalls. So, scratch that. But, the patch modifies `de_thread`, which is, in turn, called from `begin_new_exec`. And, the bug is about POSIX CPU timers and `execve`. Aha! `begin_new_exec` is looking like the right place to hone in on.

Wait a second, `begin_new_exec` actually calls into `exec_binprm` which in turn calls into `bprm_execve`. Is `begin_new_exec` *still* a good focus? Yes, it is, because it's the heart of `execve`, the transition. And now, I think `posix_cpu_timers_exit` is another crucial spot. It's called inside `de_thread`, after all. Are there other relevant functions I'm missing? There are two, `exchange_tids` and `timer_lock_sighand`, but they are static, so maybe not.

I should check the `CONFIG_POSIX_TIMERS` option, to confirm this functionality is active. Let's see if it's enabled by default, and I'll look that up in `init/Kconfig`.

{
  "File": "init/Kconfig",
  "FirstLine": 1760,
  "LineCount": 20
}

{
  "Contents": "1760:\t\n1761:\tconfig POSIX_TIMERS\n1762:\t\tbool \"Posix Clocks \u0026 timers\" if EXPERT\n1763:\t\tdefault y\n1764:\t\thelp\n1765:\t\t  This includes native support for POSIX timers to the kernel.\n1766:\t\t  Some embedded systems have no use for them and therefore they\n1767:\t\t  can be configured out to reduce the size of the kernel image.\n1768:\t\n1769:\t\t  When this option is disabled, the following syscalls won't be\n1770:\t\t  available: timer_create, timer_gettime: timer_getoverrun,\n1771:\t\t  timer_settime, timer_delete, clock_adjtime, getitimer,\n1772:\t\t  setitimer, alarm. Furthermore, the clock_settime, clock_gettime,\n1773:\t\t  clock_getres and clock_nanosleep syscalls will be limited to\n1774:\t\t  CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.\n1775:\t\n1776:\t\t  If unsure say y.\n1777:\t\n1778:\tconfig PRINTK\n1779:\t\tdefault y\n"
}

gemini-3.1-pro-preview

null

null

							input: 27390
							output: 156
							thoughts: 307
						

**My Analysis of the POSIX Timers Patch**

Okay, so the `CONFIG_POSIX_TIMERS` option is enabled by default, but it's important enough that we need to explicitly include it in `EnableConfigs`. Let's get this organized:

*   **WorthFuzzing:** Absolutely, this patch is a good candidate.
*   **FocusSymbols:** `begin_new_exec` and `posix_cpu_timers_exit`.
*   **EnableConfigs:** Just `POSIX_TIMERS`. Nothing else is needed.

The core of it is this: The patch corrects a flaw in `de_thread`.  Specifically, POSIX CPU timers were getting missed during the PID handoff within `exchange_tids()` which would lead to a lookup failure in `timer_lock_sighand()`. The fix simply adds a call to `posix_cpu_timers_exit(tsk)` within `de_thread()`. This is happening during the `execve` path, which is always interesting from a fuzzing perspective, because any issue in the `execve` path has widespread impact.

I needed to make sure that `posix_cpu_timers_exit` was actually exported, and it is, it's global within `kernel/time/posix-cpu-timers.c`. Similarly, `begin_new_exec` is global in `fs/exec.c`.

I double checked that `POSIX_TIMERS` was the only required config – confirmed it's used in an `#ifdef` and nothing else is needed. I'm ready to call `set-results`.

{
  "EnableConfigs": [
    "POSIX_TIMERS"
  ],
  "FocusSymbols": [
    "begin_new_exec",
    "posix_cpu_timers_exit"
  ],
  "Reasoning": "The patch fixes a bug in `de_thread` where POSIX CPU timers are not properly dequeued before `exchange_tids()` hands the thread's PID to the old leader, which can cause a PID lookup failure in `timer_lock_sighand()`. The fix adds a call to `posix_cpu_timers_exit(tsk)` in `de_thread()`. This is a functional change in the core kernel (execve path) and is worth fuzzing.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "POSIX_TIMERS"
  ],
  "FocusSymbols": [
    "begin_new_exec",
    "posix_cpu_timers_exit"
  ],
  "Reasoning": "The patch fixes a bug in `de_thread` where POSIX CPU timers are not properly dequeued before `exchange_tids()` hands the thread's PID to the old leader, which can cause a PID lookup failure in `timer_lock_sighand()`. The fix adds a call to `posix_cpu_timers_exit(tsk)` in `de_thread()`. This is a functional change in the core kernel (execve path) and is worth fuzzing.",
  "WorthFuzzing": true
}

{
  "WorthFuzzing": true
}

null

best-expensive

null

{
  "KMSANReasoning": "The patch fixes a bug related to POSIX CPU timers during thread group leadership changes (de_thread). It dequeues the per-thread CPU timers before the thread's PID is handed to the old leader. This prevents issues where the timer subsystem might fail to look up the PID or access freed/invalid structures. The changes involve locking and timer management, which are related to use-after-free, NULL pointer dereferences, or logic bugs. These types of bugs are caught by KASAN or standard kernel debugging tools. The patch does not introduce any new allocations, structures copied to user space, or logic that could expose uninitialized memory, so KMSAN is not applicable here.",
  "NeedsKMSAN": false
}

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.

For your convenience, here is the diff of the changes:
commit 777ec0bdac36a44512a00c64ff491a6d9fa9c342
Author: syz-cluster <triage@syzkaller.com>
Date:   Sun Aug 9 02:54:14 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/exec.c b/fs/exec.c
index c7b8f2d6366c4..f80f70e1c26de 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1000,6 +1000,18 @@ static int de_thread(struct task_struct *tsk)
 		 * the former thread group leader:
 		 */
 
+#ifdef CONFIG_POSIX_TIMERS
+		/*
+		 * exchange_tids() hands this thread's PID to the old leader,
+		 * which is reaped right after. The PID lookup in
+		 * timer_lock_sighand() then fails while the per thread CPU
+		 * timers are still queued here, so dequeue them first.
+		 */
+		spin_lock(lock);
+		posix_cpu_timers_exit(tsk);
+		spin_unlock(lock);
+#endif
+
 		/* Become a process group leader with the old leader's pid.
 		 * The old leader becomes a thread of the this thread group.
 		 */

gemini-3.1-pro-preview

null

null

							input: 2052
							output: 165
							thoughts: 294
						

**Analyzing the POSIX Timer Fix in `fs/exec.c`**

Okay, so this patch is touching `fs/exec.c`, specifically the `de_thread` function, and it's conditional on `CONFIG_POSIX_TIMERS` being enabled. Immediately, I see it's dealing with POSIX timers, which is a key indicator of where this patch's focus lies.

The patch introduces a spinlock-protected call to `posix_cpu_timers_exit(tsk)`. The comment is the crucial piece here: it highlights the problem being addressed. It seems `exchange_tids()` is transferring the thread's PID to the old leader, which is subsequently reaped. The critical timing issue is that the PID lookup within `timer_lock_sighand()` fails *while* the thread's CPU timers are still queued, meaning there's a race condition where a timer might fire after the thread's data is already freed. That points to this being related to a likely use-after-free scenario, a NULL pointer dereference, a locking issue related to timing, or a timer firing after the thread has exited.

Essentially, this is a race condition between thread reaping and timer execution, and the patch is attempting to ensure that the timers are dequeued before the thread's PID is reassigned and its resources can be freed. The likely scenario is the timer tries to dereference memory after the thread has exited, likely causing a kernel panic or unexpected behavior.

Given the nature of the fix, I can confidently say that this patch is not related to uninitialized memory issues or information leaks, which is good. KASAN, KCSAN, or lockdep would have probably caught any problems, or it could be a logic bug and a tool wasn't needed to fix it. We don't see any new memory being exposed.

Let's quickly check `posix_cpu_timers_exit` to verify it's just dequeuing timers. It doesn't introduce or involve uninitialized memory.

So, I will set `NeedsKMSAN=false` because it appears to be a logic bug with timing and locking, not a memory safety issue that KMSAN would target.

{
  "KMSANReasoning": "The patch fixes a bug related to POSIX CPU timers during thread group leadership changes (de_thread). It dequeues the per-thread CPU timers before the thread's PID is handed to the old leader. This prevents issues where the timer subsystem might fail to look up the PID or access freed/invalid structures. The changes involve locking and timer management, which are related to use-after-free, NULL pointer dereferences, or logic bugs. These types of bugs are caught by KASAN or standard kernel debugging tools. The patch does not introduce any new allocations, structures copied to user space, or logic that could expose uninitialized memory, so KMSAN is not applicable here.",
  "NeedsKMSAN": false
}

{
  "KMSANReasoning": "The patch fixes a bug related to POSIX CPU timers during thread group leadership changes (de_thread). It dequeues the per-thread CPU timers before the thread's PID is handed to the old leader. This prevents issues where the timer subsystem might fail to look up the PID or access freed/invalid structures. The changes involve locking and timer management, which are related to use-after-free, NULL pointer dereferences, or logic bugs. These types of bugs are caught by KASAN or standard kernel debugging tools. The patch does not introduce any new allocations, structures copied to user space, or logic that could expose uninitialized memory, so KMSAN is not applicable here.",
  "NeedsKMSAN": false
}