mlock - Linux

Overview

The mlock command is used in Linux to lock a section of the process's address space into RAM, preventing that memory from being paged to the swap area. This command is crucial for applications that require consistent, low-latency access to memory, such as real-time processing or when dealing with sensitive data that should not be written to disk.

Syntax

mlock [OPTIONS] ADDRESS LENGTH
  • ADDRESS specifies the starting address of the memory region to lock.
  • LENGTH indicates the number of bytes to lock from the starting address.

Options/Flags

  • -p, --pid: Specify the process ID for targeting specific process memory.
  • -u, --unlock: Unlocks the previously locked memory region.
  • -v, --verbose: Provides detailed output about the operation.

Examples

  1. Locking memory for a specific process: 
    mlock -p 12345 0x00100000 1024
  2. Unlocking a memory region: 
    mlock -u 0x00100000 1024

Common Issues

Users might encounter errors if they do not have permission to lock memory or if the specified memory range is invalid. Ensuring correct user permissions and validating memory addresses are essential steps before using mlock.

Integration

Combine mlock with other commands like ps for managing process memory more effectively:

mlock -p $(ps aux | grep 'application_name' | awk '{print $2}') ADDRESS LENGTH
  • munlock: Unlocks memory locked by mlock.
  • mlockall: Locks all of the calling process's virtual address space into RAM.
  • munlockall: Unlocks all memory previously locked by mlockall.