Re: loops in get_user_pages() for VM_IO

["David S. Miller" <davem@davemloft.net>]

On Tue, 16 Nov 2004 17:53:28 -0800
"David S. Miller" <davem@davemloft.net> wrote:

> Some time recently, I don't know when, the logic in get_user_pages()
> appears to have been changed a bit.

Replying to myself, this hang started when do_mmap_pgoff() was
changed to re-read the vma->vm_flags bits right before we
vma_link() the vma into the mm.

Previously, only the mmap() call specified vm_flags would
be used, but now we also get whatever bit changes to
vma->vm_flags are done by the file->f_op->mmap() method
as well.

In any event, it is still an open question whether get_user_pages()
and thus make_pages_present() is meant to be able to handle
VM_IO areas.