Re: [GIT PULL] aio: changes for 3.19

Benjamin LaHaise
2014-12-14T23:08:13Z

On Mon, Dec 15, 2014 at 01:02:08AM +0200, Kirill A. Shutemov wrote:
> But it seems the problem is bigger than what the patch fixes. To me we are
> too permisive on what vma can be remapped.
>
> How can we know that it's okay to move vma around for random driver which
> provide .mmap? Or I miss something obvious?

Most drivers do not care if a vma is moved within the virtual address space
of a process. The aio ring buffer is special in that it gets unmapped when
userspace does an io_destroy(), and io_destroy() has to know what the address
is moved to in order to perform the unmap. Normal drivers don't perform the
unmap themselves.

-ben
--
"Thought is the essence of where you are now."