On Wed, Nov 8, 2023 at 9:15 AM Stefan Roesch <shr@xxxxxxxxxxxx> wrote: > > While qualifiying the 6.4 release, the following warning was detected in > messages: > > vmstat_refresh: nr_file_hugepages -15664 > > The warning is caused by the incorrect updating of the NR_FILE_THPS > counter in the function split_huge_page_to_list. The if case is checking > for folio_test_swapbacked, but the else case is missing the check for > folio_test_pmd_mappable. The other functions that manipulate the counter > like __filemap_add_folio and filemap_unaccount_folio have the > corresponding check. > > I have a test case, which reproduces the problem. It can be found here: > https://github.com/sroeschus/testcase/blob/main/vmstat_refresh/madv.c > > The test case reproduces on an XFS filesystem. Running the same test > case on a BTRFS filesystem does not reproduce the problem. > > AFAIK version 6.1 until 6.6 are affected by this problem. > > Signed-off-by: Stefan Roesch <shr@xxxxxxxxxxxx> > Co-debugged-by: Johannes Weiner <hannes@xxxxxxxxxxx> > Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx Reviewed-by: Yang Shi <shy828301@xxxxxxxxx> > --- > mm/huge_memory.c | 16 +++++++++------- > 1 file changed, 9 insertions(+), 7 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 064fbd90822b4..874000f97bfc1 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2737,13 +2737,15 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) > int nr = folio_nr_pages(folio); > > xas_split(&xas, folio, folio_order(folio)); > - if (folio_test_swapbacked(folio)) { > - __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, > - -nr); > - } else { > - __lruvec_stat_mod_folio(folio, NR_FILE_THPS, > - -nr); > - filemap_nr_thps_dec(mapping); > + if (folio_test_pmd_mappable(folio)) { > + if (folio_test_swapbacked(folio)) { > + __lruvec_stat_mod_folio(folio, > + NR_SHMEM_THPS, -nr); > + } else { > + __lruvec_stat_mod_folio(folio, > + NR_FILE_THPS, -nr); > + filemap_nr_thps_dec(mapping); > + } > } > } > > > base-commit: ffc253263a1375a65fa6c9f62a893e9767fbebfa > -- > 2.39.3 > >
