CVE-2026-98861 fprobe: Use guard(rcu_sched_notrace) and check rcu_is_watching()

In the Linux kernel, the following vulnerability has been resolved: fprobe: Use guardrcuschednotrace and check rcuiswatching unregisterfprobe and unregisterfprobeasync used by BPF kprobe-multi rely on standard RCU grace periods synchronizercu and callrcu to wait until in-flight fprobe handlers...