What doest the message "kernel: Write protecting the kernel read-only data: 527k" mean

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 5

Issue

  • It's easily to see such messages in /var/log/messages:
# grep -i read-only /var/log/mess* 
messages.2:Jan 4 17:20:44 localhost kernel: Write protecting the kernel read-only data: 527k
messages.3:Dec 27 17:05:11 localhost kernel: Write protecting the kernel read-only data: 527k
  • What does the message mean?

Resolution

  • This message has no side effect. It's expected and each time system reboot, it will be recorded in /var/log/messages.

Root Cause

  • This is an ordinary message kernel generates when virtual memory is mapping to physical memory, and kernel is loaded read-only for protecting it.

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