Re: [PATCH v2] mm: Fix for negative counter: nr_file_hugepages

Matthew Wilcox willy@infradead.org writes:

On Tue, Nov 07, 2023 at 10:18:05AM -0800, Stefan Roesch wrote:

...

+++ b/mm/huge_memory.c @@ -2740,7 +2740,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) if (folio_test_swapbacked(folio)) { __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, -nr);

• 	} else {
  

• 	} else if (folio_test_pmd_mappable(folio)) {
  	__lruvec_stat_mod_folio(folio, NR_FILE_THPS,
  				-nr);
  	filemap_nr_thps_dec(mapping);
  

As I said, we also need the folio_test_pmd_mappable() for swapbacked. Not because there's currently a problem, but because we don't leave landmines for other people to trip over in future!

I'll add it in the next version.