Re: [PATCH 1/9] mm: Provide new get_vaddr_pfns() helper

[Jan Kara <jack@suse.cz>]

On Mon 17-03-14 13:53:35, Dave Hansen wrote:
> On 03/17/2014 12:49 PM, Jan Kara wrote:
> > +int get_vaddr_pfns(unsigned long start, int nr_pfns, int write, int force,
> > +		   struct pinned_pfns *pfns)
> > +{
> ...
> > +	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
> > +		pfns->got_ref = 1;
> > +		pfns->is_pages = 1;
> > +		ret = get_user_pages(current, mm, start, nr_pfns, write, force,
> > +				     pfns_vector_pages(pfns), NULL);
> > +		goto out;
> > +	}
> 
> Have you given any thought to how this should deal with VM_MIXEDMAP
> vmas?  get_user_pages() will freak when it hits the !vm_normal_page()
> test on the pfnmapped ones, and jump out.  Shouldn't get_vaddr_pfns() be
> able to handle those too?
  It could and it doesn't seem as a big complication. Although none of the
converted drivers need this functionality, I guess it makes sense to
implement this to make the API more consistent. So I can have a look at it
for the next iteration.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

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