There are many slightly different prototypes for this syscall, but none of them is like the documented one. Of all the different prototypes, let's document the asm-generic one. This manual page was actually using a prototype similar to mmap(2), but there's no glibc wrapper function called mmap2(2), as the wrapper for this syscall is mmap(2). Therefore, the documented prototype should be the kernel one. ...... .../linux$ grep_syscall mmap2 arch/csky/kernel/syscall.c:17: SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len, unsigned long, prot, unsigned long, flags, unsigned long, fd, off_t, offset) arch/microblaze/kernel/sys_microblaze.c:46: SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len, unsigned long, prot, unsigned long, flags, unsigned long, fd, unsigned long, pgoff) arch/nds32/kernel/sys_nds32.c:12: SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len, unsigned long, prot, unsigned long, flags, unsigned long, fd, unsigned long, pgoff) arch/powerpc/kernel/syscalls.c:60: SYSCALL_DEFINE6(mmap2, unsigned long, addr, size_t, len, unsigned long, prot, unsigned long, flags, unsigned long, fd, unsigned long, pgoff) arch/riscv/kernel/sys_riscv.c:37: SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len, unsigned long, prot, unsigned long, flags, unsigned long, fd, off_t, offset) arch/s390/kernel/sys_s390.c:49: SYSCALL_DEFINE1(mmap2, struct s390_mmap_arg_struct __user *, arg) arch/sparc/kernel/sys_sparc_32.c:101: SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len, unsigned long, prot, unsigned long, flags, unsigned long, fd, unsigned long, pgoff) arch/ia64/include/asm/unistd.h:30: asmlinkage unsigned long sys_mmap2( unsigned long addr, unsigned long len, int prot, int flags, int fd, long pgoff); arch/ia64/kernel/sys_ia64.c:139: asmlinkage unsigned long sys_mmap2 (unsigned long addr, unsigned long len, int prot, int flags, int fd, long pgoff) arch/m68k/kernel/sys_m68k.c:40: asmlinkage long sys_mmap2(unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, unsigned long fd, unsigned long pgoff) arch/parisc/kernel/sys_parisc.c:275: asmlinkage unsigned long sys_mmap2(unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, unsigned long fd, unsigned long pgoff) arch/powerpc/include/asm/syscalls.h:15: asmlinkage long sys_mmap2(unsigned long addr, size_t len, unsigned long prot, unsigned long flags, unsigned long fd, unsigned long pgoff); arch/sh/include/asm/syscalls.h:8: asmlinkage long sys_mmap2(unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, unsigned long fd, unsigned long pgoff); arch/sh/kernel/sys_sh.c:41: asmlinkage long sys_mmap2(unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, unsigned long fd, unsigned long pgoff) arch/sparc/kernel/systbls.h:23: asmlinkage long sys_mmap2(unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, unsigned long fd, unsigned long pgoff); include/asm-generic/syscalls.h:14: asmlinkage long sys_mmap2(unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, unsigned long fd, unsigned long pgoff); .../linux$ function grep_syscall() { if ! [ -v 1 ]; then >&2 echo "Usage: ${FUNCNAME[0]} <syscall>"; return ${EX_USAGE}; fi find * -type f \ |grep '\.c$' \ |sort -V \ |xargs pcregrep -Mn "(?s)^\w*SYSCALL_DEFINE.\(${1},.*?\)" \ |sed -E 's/^[^:]+:[0-9]+:/&\n/'; find * -type f \ |grep '\.[ch]$' \ |sort -V \ |xargs pcregrep -Mn "(?s)^asmlinkage\s+[\w\s]+\**sys_${1}\s*\(.*?\)" \ |sed -E 's/^[^:]+:[0-9]+:/&\n/'; } Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com> Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>