On Thu, Dec 15, 2022 at 09:48:41AM +0800, Chao Yu wrote: > On 2022/12/13 3:13, Vishal Moola (Oracle) wrote: > > +add_more: > > + pages[nr_pages] = folio_page(folio,idx); > > + folio_ref_inc(folio); > > It looks if CONFIG_LRU_GEN is not set, folio_ref_inc() does nothing. For those > folios recorded in pages array, we need to call folio_get() here to add one more > reference on each of them? static inline void folio_get(struct folio *folio) { VM_BUG_ON_FOLIO(folio_ref_zero_or_close_to_overflow(folio), folio); folio_ref_inc(folio); } That said, folio_ref_inct() is very much MM-internal and filesystems should be using folio_get(), so please make that modification in the next revision, Vishal.