Re: [PATCH 1/2] pagevec: Allow pagevecs to be different sizes

[Matthew Wilcox <willy@infradead.org>]

On Fri, Nov 06, 2020 at 09:17:43AM -0800, Tim Chen wrote:
> 
> >  
> > +static inline unsigned pagevec_size(struct pagevec *pvec)
> > +{
> > +	return pvec->sz;
> > +}
> > +
> >  static inline unsigned pagevec_count(struct pagevec *pvec)
> >  {
> 
> Willy,
> 
> I was expecting pagevec_size to be used in pagevec_lookup_range*
> where we hardcoded the pagevec's top range to look for pages
> as PAGEVEC_SIZE.  You define pagevec_size but seems like it is not used.
> Or am I missing something?  

I have a number of changes already in that area that are currently in-flight.

https://lore.kernel.org/linux-mm/20201026041408.25230-1-willy@infradead.org/

(although I should modify patch 9/12 to not use PAGEVEC_SIZE directly)

I have some patches that I haven't bothered sending yet since I have so
many other outstanding patches to do something similar to find_get_pages()
/ find_get_pages_range() / pagevec_lookup() / pagevec_lookup_range().


The trace you sent showed the problem being with the lru_add pagevec,
and that's never used with the pagevec_lookup_* APIs (afaik), so I didn't
see it as urgent to fix those.