On Tue, Aug 04, 2020 at 12:17:34PM -0700, John Hubbard wrote:
> On 8/4/20 11:48 AM, Matthew Wilcox wrote:
> > On Tue, Aug 04, 2020 at 11:39:43AM -0700, John Hubbard wrote:
> > > +static inline int __compound_mapcount(struct page *page)
> > > +{
> > > + page = compound_head(page);
> > > + return atomic_read(compound_mapcount_ptr(page)) + 1;
> > > +}
> >
> > I'd suggest instead:
> >
> > static inline int head_mapcount(struct page *head)
> > {
> > return atomic_read(compound_mapcount_ptr(head)) + 1;
> > }
> >
> > > +static inline int dump_page_compound_mapcount(struct page *page)
> > > +{
> > > + if (WARN_ON_ONCE(!PageCompound(page)))
> > > + return 0;
> > > + return __compound_mapcount(page);
> > > }
> >
> > And just dropping this ... it shouldn't be used outside mm/debug.c anyway.
>
> Yes, that's cleaner. I'll send a v2 that is not a reply, so that Andrew can
> spot it more easily. OK to add your "Suggested-by:" to that?
Of course! Thanks!
> > Thinking about it, we'll get the hint later that this is not to be trusted
> > when the flags from the page do not include 'head'.
> >
>
> Good point. I think this will work out pretty well, then.
>
> thanks,
> --
> John Hubbard
> NVIDIA
