On Mon, May 6, 2024 at 10:00 AM Yosry Ahmed <yosryahmed@xxxxxxxxxx> wrote: > > Do not use __lruvec_stat_mod_folio() when updating NR_FILE_PMDMAPPED and > NR_SHMEM_PMDMAPPED as these stats are not maintained per-memcg. Use > __mod_node_page_state() instead, which updates the global per-node stats > only. > > Reported-by: syzbot+9319a4268a640e26b72b@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://lore.kernel.org/lkml/0000000000001b9d500617c8b23c@xxxxxxxxxx > Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx> > --- > mm/rmap.c | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/mm/rmap.c b/mm/rmap.c > index 12be4241474ab..c2cfb750d2535 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1435,13 +1435,14 @@ static __always_inline void __folio_add_file_rmap(struct folio *folio, > struct page *page, int nr_pages, struct vm_area_struct *vma, > enum rmap_level level) > { > + pg_data_t *pgdat = folio_pgdat(folio); > int nr, nr_pmdmapped = 0; > > VM_WARN_ON_FOLIO(folio_test_anon(folio), folio); > > nr = __folio_add_rmap(folio, page, nr_pages, level, &nr_pmdmapped); > if (nr_pmdmapped) > - __lruvec_stat_mod_folio(folio, folio_test_swapbacked(folio) ? > + __mod_node_page_state(pgdat, folio_test_swapbacked(folio) ? > NR_SHMEM_PMDMAPPED : NR_FILE_PMDMAPPED, nr_pmdmapped); > if (nr) > __lruvec_stat_mod_folio(folio, NR_FILE_MAPPED, nr); > @@ -1493,6 +1494,7 @@ static __always_inline void __folio_remove_rmap(struct folio *folio, > enum rmap_level level) > { > atomic_t *mapped = &folio->_nr_pages_mapped; > + pg_data_t *pgdat = folio_pgdat(folio); > int last, nr = 0, nr_pmdmapped = 0; > bool partially_mapped = false; > enum node_stat_item idx; > @@ -1540,13 +1542,14 @@ static __always_inline void __folio_remove_rmap(struct folio *folio, > } > > if (nr_pmdmapped) { > + /* NR_{FILE/SHMEM}_PMDMAPPED are not maintained per-memcg */ > if (folio_test_anon(folio)) > - idx = NR_ANON_THPS; > - else if (folio_test_swapbacked(folio)) > - idx = NR_SHMEM_PMDMAPPED; > + __lruvec_stat_mod_folio(folio, NR_ANON_THPS, -nr_pmdmapped); > else > - idx = NR_FILE_PMDMAPPED; > - __lruvec_stat_mod_folio(folio, idx, -nr_pmdmapped); > + __mod_node_page_state(pgdat, > + folio_test_swapbacked(folio) ? > + NR_SHMEM_PMDMAPPED : NR_FILE_PMDMAPPED, > + nr_pmdmapped); ..and of course right after I press send I realized this should be -nr_pmdmapped. > } > if (nr) { > idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED; > -- > 2.45.0.rc1.225.g2a3ae87e7f-goog >
