where to set framebuffer page read-only,when using differred IO?

[april]

Hi all:
I'm writing a driver, and want to catch the cpu write and just flush
page that cpu write before device engine access.
may be some thing like differred IO.
I read the differred IO and fb 's code, I can't found where it set the
page table entries for framebuffer pages to read-only.

Could anyone help to show where the frame buffer page set to read-only?

Thanks in advance
Aapril
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/