Re: [PATCH v5 01/12] mm: support madvise(MADV_FREE)

[Minchan Kim <minchan@kernel.org>]

On Mon, Nov 30, 2015 at 10:20:25AM +0200, Mika Penttilä wrote:
> > +		 * If pmd isn't transhuge but the page is THP and
> > +		 * is owned by only this process, split it and
> > +		 * deactivate all pages.
> > +		 */
> > +		if (PageTransCompound(page)) {
> > +			if (page_mapcount(page) != 1)
> > +				goto out;
> > +			get_page(page);
> > +			if (!trylock_page(page)) {
> > +				put_page(page);
> > +				goto out;
> > +			}
> > +			pte_unmap_unlock(orig_pte, ptl);
> > +			if (split_huge_page(page)) {
> > +				unlock_page(page);
> > +				put_page(page);
> > +				pte_offset_map_lock(mm, pmd, addr, &ptl);
> > +				goto out;
> > +			}
> > +			pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
> > +			pte--;
> > +			addr -= PAGE_SIZE;
> > +			continue;
> > +		}
> 
> looks like this leaks page count if split_huge_page() is succesfull
> (returns zero).

Even, I missed unlock_page.
Thanks for the review!