When freeing a large folio, we must remove it from the deferred split list before we uncharge it as each memcg has its own deferred split list (with associated lock) and removing a folio from the deferred split list while holding the wrong lock will corrupt that list and cause various related problems. Link: https://lore.kernel.org/linux-mm/367a14f7-340e-4b29-90ae-bc3fcefdd5f4@xxxxxxx/ Fixes: f77171d241e3 (mm: allow non-hugetlb large folios to be batch processed) Fixes: 29f3843026cf (mm: free folios directly in move_folios_to_lru()) Fixes: bc2ff4cbc329 (mm: free folios in a batch in shrink_folio_list()) Debugged-by: Ryan Roberts <ryan.roberts@xxxxxxx> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Tested-by: Ryan Roberts <ryan.roberts@xxxxxxx> --- v2: Add two more places Ryan spotted mm/swap.c | 3 +++ mm/vmscan.c | 6 ++++++ 2 files changed, 9 insertions(+) diff --git a/mm/swap.c b/mm/swap.c index eaadbacf7f19..500a09a48dfd 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -1012,6 +1012,9 @@ void folios_put_refs(struct folio_batch *folios, unsigned int *refs) free_huge_folio(folio); continue; } + if (folio_test_large(folio) && + folio_test_large_rmappable(folio)) + folio_undo_large_rmappable(folio); __page_cache_release(folio, &lruvec, &flags); diff --git a/mm/vmscan.c b/mm/vmscan.c index a0e53999a865..766da7de9e27 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1436,6 +1436,9 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, */ nr_reclaimed += nr_pages; + if (folio_test_large(folio) && + folio_test_large_rmappable(folio)) + folio_undo_large_rmappable(folio); if (folio_batch_add(&free_folios, folio) == 0) { mem_cgroup_uncharge_folios(&free_folios); try_to_unmap_flush(); @@ -1842,6 +1845,9 @@ static unsigned int move_folios_to_lru(struct lruvec *lruvec, if (unlikely(folio_put_testzero(folio))) { __folio_clear_lru_flags(folio); + if (folio_test_large(folio) && + folio_test_large_rmappable(folio)) + folio_undo_large_rmappable(folio); if (folio_batch_add(&free_folios, folio) == 0) { spin_unlock_irq(&lruvec->lru_lock); mem_cgroup_uncharge_folios(&free_folios); -- 2.43.0
