_PAGE_HWWRITE missing in pte_mkdirty()?

[Paul Mackerras]

Joakim Tjernlund writes:

> OK, I wasn't aware that you can have dirty pages without _PAGE_RW.

Yes, think about what happens if a process has a writable dirty page
(in a private or anonymous mapping) and the process does a fork.  The
page becomes copy-on-write, so we have to make it non-writable, but it
is still dirty.

Whether the kernel actually ever calls pte_mkdirty on a non-writable
page is a different question, of course. :)

Paul.

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