How to really write-protect a page

How to really write-protect a page

[Jidong Xiao]

Hi,

For some reason, I want to write protect a special page, but I don't
know how to set it as read-only.

I am reading the book "Understanding The Linux Virtual Memory Manager".

In section 5.6.4, there is saying:

"During fork, the PTEs of the two processes are made read-only so that
when a write occurs there will be a page fault. Linux recognises a COW
page because even though the PTE is write protected, the controlling
VMA shows the region is writable."

My question is, if I really want write protect a page, say, I don't
want a copy-on-write happens, I just hope the page is really
read-only, can I achieve that by setting "the controlling VMA" as
non-writable? Or how to do that?

Thank you!

Regards
Jidong

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