Re: [PATCH v5 10/12] mm/gup: /proc/vmstat: pin_user_pages (FOLL_PIN) reporting

[John Hubbard]

On 2/10/20 2:16 AM, Jan Kara wrote:
> On Thu 06-02-20 19:37:33, John Hubbard wrote:
> > @@ -2258,6 +2268,8 @@ static int record_subpages(struct page *page, unsigned long addr,
> >   
> >   static void put_compound_head(struct page *page, int refs, unsigned int flags)
> >   {
> > +	int orig_refs = refs;
> > +
> >   	if (flags & FOLL_PIN) {
> >   		if (hpage_pincount_available(page))
> >   			hpage_pincount_sub(page, refs);
> > @@ -2273,6 +2285,8 @@ static void put_compound_head(struct page *page, int refs, unsigned int flags)
> >   	if (refs > 1)
> >   		page_ref_sub(page, refs - 1);
> >   	put_page(page);
> > +
> > +	mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_RELEASED, orig_refs);
> >   }
>
> Still not quite happy about this :) Now you update NR_FOLL_PIN_RELEASED
> even if 'flags' don't have FOLL_PIN set. You need to have the
> mod_node_page_state() inside the "if (flags & FOLL_PIN)" branch above...
>
> 									Honza

Arggh, yes that's true. Thanks for catching that, will fix in v6.


thanks,
--
John Hubbard
NVIDIA