Re: Any reason why install_page and zap_page_range are not exported?

From: Andrew Morton (akpm@osdl.org)
Date: Thu Jul 31 2003 - 17:16:11 EST


"Petr Vandrovec" <VANDROVE@vc.cvut.cz> wrote:
>
> Hi,
> in one of my projects I found that what we were doing in 2.2.x/2.4.x
> with strange hacks to mmap & nopage methods to get non-linear
> mappings from some device can be done in 2.[56].x with remap_file_pages.
>
> Only two things are missing: install_page is not exported for modules,
> so it is not possible to create own vma's populate function, as
> there is no way how to put some page into pagetables. Or at least
> I did not found such - even if I'll copy install_page's code to the
> module, I'll just run to the other non-exported symbols :-(

Agree, install_page() should be exported. I'll submit a patch.

> And second missing thing is zap_page_range - we need way to tell
> that specified page is not mapped anywhere (mostly for debugging
> purposes). At worst install_page with PROT_NONE protection can be
> used for that, but it seems natural that if there should be no page
> there, we should just put nothing to the pagetables instead of some
> fake page. And for large ranges doing one 200MB zap_page_range is
> much faster than doing 50000 install_pages.

zap_page_range() sounds like an odd thing to be exporting. If we had an
in-kernel module which needed it then OK. Do you have plans in that
direction?
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