runtime/pprof: StopCPUProfile causes SIGKILL on Linux kernel 6.12

[benjajaja]

Does this issue reproduce with the latest release?

Yes, go1.24.5 is the latest release.

What did you do?

package main

import (
	"fmt"
	"io"
	"runtime/pprof"
	"time"
)

func main() {
	fmt.Println("Starting CPU profile...")
	pprof.StartCPUProfile(io.Discard)
	time.Sleep(3 * time.Second)
	fmt.Println("Stopping profile...")
	pprof.StopCPUProfile()
	fmt.Println("Done")
}

Run multiple times - fails intermittently:

$ go build -o test && for i in {1..5}; do ./test; echo "exit: $?"; done

What did you expect to see?

Starting CPU profile...
Stopping profile...
Done
exit: 0

What did you see instead?

Intermittently, the process is killed with SIGKILL (exit 137) during StopCPUProfile():

Starting CPU profile...
Stopping profile...
Killed
exit: 137

Strace shows timer_delete() succeeds, then SIGKILL arrives from outside the process:

[pid 967876] timer_delete(1) = 0
[pid 967876] setitimer(ITIMER_PROF, {0, 0}, NULL) = 0
[pid 967877] +++ killed by SIGKILL +++
[pid 967876] +++ killed by SIGKILL +++
+++ killed by SIGKILL +++

Additional notes:

• Issue appeared after upgrading NixOS 25.05 → 25.11 (including kernel from 6.6 to 6.12 wrong info sorry, actually: 6.12.41 → 6.12.59)
• Kernel has CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y
• Possibly related to misc/cgo/testcarchive: TestSIGPROF flakes with "signal: profiling timer expired" #19320, misc/cgo/testcarchive: TestSIGPROF failures with "signal: profiling timer expired" #43828

[linsite]

It doesn't reproduce on 6.14.

$ grep CONFIG_POSIX_CPU_TIMERS_TASK_WORK /boot/config-6.14.0-36-generic
CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y

$ go run run.go
Starting CPU profile...
Stopping profile...
Done

[prattmic]

Does dmesg mention why it is killed? e.g., OOM, or syscall filter violation?

[DanielMorsing]

Does this reproduce on later go versions? try running defining GOTOOLCHAIN=go1.25.5 before you run your reproducer

[benjajaja]

> go version
go version go1.24.6 linux/amd64
> go run test.go 
Starting CPU profile...
Stopping profile...
signal: killed

> go version
go version go1.25.5 linux/amd64
> go run test.go 
Starting CPU profile...
Stopping profile...
signal: killed

Nothing in dmesg.

Re: kernel version, I have no idea if that's relevant, it's just a fact that I upgraded.

[gabyhelp]

Related Issues

• runtime/pprof: test timed out in `StartCPUProfile` #60108 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[linsite]

I've build a 6.12.59, but failed to reproduce. Is there any thing that I may overlook?

[lin@nixos:~/opt]$ cat /proc/version
Linux version 6.12.59 (nixbld@localhost) (gcc (GCC) 14.3.0, GNU ld (GNU Binutils) 2.44) #1-NixOS SMP PREEMPT_DYNAMIC Mon Nov 24 09:36:08 UTC 2025

[lin@nixos:~/opt]$ go/bin/go version
go version go1.25.1 linux/amd64

[lin@nixos:~/opt]$ ./perf
Starting CPU profile...
Stopping profile...
Done

[lin@nixos:~/opt]$ zgrep CONFIG_POSIX_CPU_TIMERS_TASK_WORK /proc/config.gz
CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y

[benjajaja]

I can't reproduce now anymore either! I did NOT make any further system-updated related changes after posting this, so I don't have the slightest clue.

Closing until it reproduces again, I guess.