Re: ioremap_nocache problem?

[Stephen C. Tweedie]

Hi,

On Thu, Jan 25, 2001 at 10:49:50AM -0600, Timur Tabi wrote:
> 
> > set_bit(PG_reserved, &page->flags);
> > 	ioremap();
> > 	...
> > 	iounmap();
> > 	clear_bit(PG_reserved, &page->flags);
> 
> The problem with this is that between the ioremap and iounmap, the page is
> reserved.  What happens if that page belongs to some disk buffer or user
> process, and some other process tries to free it.  Won't that cause a problem?

It depends on how it is being used, but yes, it is likely to --- page
reference counts won't be updated properly on reserved pages, for
example.  Why on earth do you want to do ioremap of something like a
page cache page, though?  That is _not_ what ioremap is designed for!

--Stephen