Re: [PATCHv5 22/36] mm, hugetlb: switch hugetlbfs to multi-order radix-tree entries

[Kirill A. Shutemov]

On Wed, Nov 30, 2016 at 05:48:05PM +0800, Hillf Danton wrote:
> On Tuesday, November 29, 2016 7:23 PM Kirill A. Shutemov wrote:
> > @@ -607,10 +605,10 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
> >  		}
> > 
> >  		/* Set numa allocation policy based on index */
> > -		hugetlb_set_vma_policy(&pseudo_vma, inode, index);
> > +		hugetlb_set_vma_policy(&pseudo_vma, inode, index >> huge_page_order(h));
> > 
> >  		/* addr is the offset within the file (zero based) */
> > -		addr = index * hpage_size;
> > +		addr = index << PAGE_SHIFT & ~huge_page_mask(h);
> > 
> >  		/* mutex taken here, fault path and hole punch */
> >  		hash = hugetlb_fault_mutex_hash(h, mm, &pseudo_vma, mapping,
> 
> Seems we can't use index in computing hash as long as it isn't in huge page size.

Look at changes in hugetlb_fault_mutex_hash(): we shift the index right by
huge_page_order(), before calculating the hash. I don't see a problem
here.

-- 
 Kirill A. Shutemov