Re: [PATCH v4 06/11] mm: thp: check pmd migration entry in common path

[Kirill A. Shutemov]

On Fri, Mar 24, 2017 at 11:09:25AM -0500, Zi Yan wrote:
> Kirill A. Shutemov wrote:
> > On Mon, Mar 13, 2017 at 11:45:02AM -0400, Zi Yan wrote:
> > Again. That's doesn't look right..
> 
> It will be changed:
> 
>  	ptl = pmd_lock(mm, pmd);
> +retry_locked:
> +	if (unlikely(!pmd_present(*pmd))) {
> +		if (likely(!(flags & FOLL_MIGRATION))) {
> +			spin_unlock(ptl);
> +			return no_page_table(vma, flags);
> +		}
> +		pmd_migration_entry_wait(mm, pmd);
> +		goto retry_locked;

Nope. pmd_migration_entry_wait() unlocks the ptl.

-- 
 Kirill A. Shutemov