[$] The phaseout of the mmap() file operation

The file_operations
structure in the kernel is a set of function pointers implementing, as the
name would suggest, operations on files. A subsystem that manages objects
which can be represented by a file descriptor will provide a
file_operations structure providing implementations of the various
operations that a user of the file descriptor may want to carry out. The
mmap() method, in particular, is invoked when user space calls the
mmap()
system call to map the object behind a file descriptor into its address
space. That method, though, is currently on its way out in a multi-release
process that started in 6.17.