[LTP] [PATCH] sched/fork: Fix timer_slack_ns inheritance for RT tasks

[K Prateek Nayak]

Hello Oliver,

Thank you for the test!

On 5/28/2026 10:20 AM, kernel test robot wrote:
> Suite: syscalls-05
> ──────────────────
> 
> ...
> 
> prctl02: pass | tainted  (0.011s)
> prctl08: fail | tainted  (0.011s)   <---

I think we are failing here
https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/prctl/prctl08.c#L86

for:

    {check_inherit_timerslack, 70000, 70000, "Child process"}

This checks if the default timerslack is set to the Parent's timerslack
at the time of fork and prctl(PR_SET_TIMERSLACK, 0) in the child process
expects the timer slack to go back that inherited value.

With this patch, instead of inheriting it, we are resetting it at 50us
at the time of fork. Since this is documented in man page, I believe the
test is correct and this will indeed be a behavior change.

-- 
Thanks and Regards,
Prateek