mountproc

Mountproc is the kernel-side mount handler for the proc filesystem (procfs) used by Linux and other Unix-like systems. It is invoked by the mount system call when a filesystem of type proc is requested, or during early boot when the kernel initializes the proc filesystem. The handler is part of the procfs implementation in the kernel and is responsible for creating and initializing the proc superblock and the root vfs entry that becomes /proc.

Once mounted, procfs provides a dynamic interface to kernel data structures. Files and directories under /proc expose information about active processes, system memory, CPU statistics, kernel tunables, and other runtime data. The mountproc mechanism sets up the necessary in-memory structures and file operations so that entries such as /proc/[pid], /proc/meminfo, /proc/cpuinfo, and /proc/kmsg can be created and accessed on demand. Many /proc entries are virtual files whose contents are generated on read or write by kernel code.

Modern Linux supports mounting options for proc, such as hidepid, which restricts visibility of other processes’ information. /proc is typically mounted early in the boot process but can be remounted or managed by system administrators when needed. The mountproc mechanism is an internal detail of the procfs implementation; most users interact with the interface indirectly through standard commands and file reads, rather than invoking the mount procedure directly. The proc filesystem, enabled by this mechanism, remains a central interface for observing and querying kernel and process state.