Re: [PATCH] mm:rmap: use the pra.mapcount to do the check

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 4 Apr 2019 16:08:33 -0700 Mike Kravetz <mike.kravetz@oracle.com> wrote:

> On 4/3/19 10:48 PM, Huang Shijie wrote:
> > We have the pra.mapcount already, and there is no need to call
> > the page_mapped() which may do some complicated computing
> > for compound page.
> > 
> > Signed-off-by: Huang Shijie <sjhuang@iluvatar.ai>
> 
> This looks good to me.  I had to convince myself that there were no
> issues if we were operating on a sub-page of a compound-page.  However,
> Kirill is the expert here and would know of any subtle issues I may have
> overlooked.
> 
> -- 
> Mike Kravetz
> 
> > ---
> >  mm/rmap.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/mm/rmap.c b/mm/rmap.c
> > index 76c8dfd3ae1c..6c5843dddb5a 100644
> > --- a/mm/rmap.c
> > +++ b/mm/rmap.c
> > @@ -850,7 +850,7 @@ int page_referenced(struct page *page,
> >  	};
> >  
> >  	*vm_flags = 0;
> > -	if (!page_mapped(page))
> > +	if (!pra.mapcount)
> >  		return 0;
> >  
> >  	if (!page_rmapping(page))
> >