Someone

normal run:
-----------

munmap(0xb7fde000, 47309)               = 0
fstat64(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 5), ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7fe9000
write(1, "xxx",yyy
)   = 20
fstat64(0, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 5), ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7fe8000


strace -f of my program:
------------------------

[pid 11230] munmap(0xb7fde000, 47309)   = 0
[pid 11230] fstat64(1, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
[pid 11230] mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7fe9000
[pid 11230] fstat64(0, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
[pid 11230] mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7fe8000