Re: zap_page_range in a module

[Martin Diehl]

On Fri, 14 Dec 2001, Benjamin LaHaise wrote:

> On Fri, Dec 14, 2001 at 01:26:29PM -0800, Sottek, Matthew J wrote:
> > currently can only work when compiled into the kernel because I need 
> > zap_page_rage(). Is there an acceptable way for me to get equivalent
> > functionality in a module so that this will be more useful to the
> > general public?
> 
> The vm does zap_page_range for you if you're implementing an mmap operation, 
> otherwise vmalloc/vfree/vremap will take care of the details for you.  How 
> is your code using zap_page_range?  It really shouldn't be.

True, but IMHO only for standard mmap semantics.

Well, the background is slightly different here, but very much the same
problem: I'd like to get rid of some page(s) which are mapped to an
userland vma. At certain points I need to force a page fault on this and
so the overloaded vma->nopage() gets called and can do the right thing.

zap_page_range() does exactly what I want. IMHO zap_page_range() is some
kind of symmetric buddy of remap_page_range() - it's somewhat surprizing
to find one exported but not the other one. And, AFAICS, there is no
technical reason as well, not to use it - at least for me it's working
perfectly fine. Of course it needs proper mm serialization provided by
down_write(&mm->mmap_sem).

Martin