The stap command doesn't work on FC7, latest kernel (i.e. without the fix):
# uname -a
Linux host 2.6.23.14-64.fc7 #1 SMP Sun Jan 20 22:20:19 EST 2008 x86_64 x86_64
x86_64 GNU/Linux
# stap -v -g -e 'probe syscall.vmsplice {
   printf("blocking vmsplice (%s) uid %d pid %d exec %s\n", argstr, uid(),
pid(), execname())
   $nr_segs = 0
}'
Pass 1: parsed user script and 54 library script(s) in 210usr/0sys/226real ms.
semantic error: probe point mismatch at position 1 (alternatives: accept access
acct add_key adjtimex alarm arch_prctl bdflush bind brk capget capset chdir
chmod chown chown16 chroot clock_getres clock_gettime clock_nanosleep
clock_settime close compat_getitimer compat_nanosleep compat_setitimer
compat_utime connect creat delete_module dup dup2 epoll_create epoll_ctl
epoll_wait execve exit exit_group fadvise64 fadvise64_64 fchdir fchmod fchown
fchown16 fcntl fdatasync fgetxattr flistxattr flock fork fremovexattr fsetxattr
fstat fstatfs fstatfs64 fsync ftruncate ftruncate64 futex get_mempolicy getcwd
getdents getdents64 getegid getegid16 geteuid geteuid16 getgid getgid16
getgroups getgroups16 gethostname getitimer getpeername getpgid getpgrp getpid
getppid getpriority getresgid getresgid16 getresuid getresuid16 getrlimit
getrusage getsid getsockname getsockopt gettid gettimeofday getuid getuid16
getxattr init_module io_cancel io_destroy io_getevents io_setup io_submit ioctl
ioperm iopl ioprio_get ioprio_set kexec_load keyctl kill lchown lchown16
lgetxattr link listen listxattr llistxattr llseek lookup_dcookie lremovexattr
lseek lsetxattr lstat madvise mbind mincore mkdir mkdirat mknod mlock mlockall
mmap mmap2 modify_ldt mount mprotect mq_getsetattr mq_notify mq_open
mq_timedreceive mq_timedsend mq_unlink mremap msgctl msgget msgrcv msgsnd msync
munlock munlockall munmap nanosleep nfsservctl ni_syscall nice old_getrlimit
open pause personality pipe pivot_root poll prctl pread64 ptrace pwrite64
quotactl read readahead readlink readv reboot recv recvfrom recvmsg
remap_file_pages removexattr rename request_key restart_syscall rmdir
rt_sigaction rt_sigaction32 rt_sigpending rt_sigprocmask rt_sigqueueinfo
rt_sigreturn rt_sigsuspend rt_sigtimedwait sched_get_priority_max
sched_get_priority_min sched_getaffinity sched_getparam sched_getscheduler
sched_rr_get_interval sched_setaffinity sched_yield select semctl semget semop
semtimedop send sendfile sendmsg sendto set_mempolicy set_tid_address
setdomainname setfsgid setfsgid16 setfsuid setfsuid16 setgid setgid16 setgroups
setgroups16 sethostname setitimer setpgid setpriority setregid setregid16
setresgid setresgid16 setresuid setresuid16 setreuid setreuid16 setrlimit setsid
setsockopt settimeofday settimeofday32 setuid setuid16 setxattr sgetmask shmctl
shmdt shmget shutdown sigaltstack signal sigpending sigprocmask socket
socketpair ssetmask stat statfs statfs64 stime swapoff swapon symlink sync
sysctl sysfs sysinfo syslog tgkill time timer_create timer_delete
timer_getoverrun timer_gettime timer_settime times tkill truncate tux umask
umount uname unlink uselib ustat ustat32 utime utimes vhangup wait4 waitid write
writev) while resolving probe point syscall.vmsplice
Pass 2: analyzed script: 0 probe(s), 0 function(s), 0 embed(s), 0 global(s) in
10usr/0sys/6real ms.
Pass 2: analysis failed.  Try again with more '-v' (verbose) options.