On Fri, Mar 08, 2024 at 08:34:15PM -0800, Andrew Morton wrote: > > We seem to be coming down to the wire on this one - Linus might release > 6.8 this weekend. > > Will simply dropping "mm: allow non-hugetlb large folios to be batch > processed" from mm-stable get us out of trouble? We can add a fix patch which re-narrows the race to the point where it's no longer observable. Obviously we need to figure out what the real problem is, but we could be going back a long way. We've definitely found two bugs in the process of investigating the problem (of arguable import; the migration one merely wastes memory temporarily and it's not entirely clear that the wrong-lock problem definitely causes a crash) diff --git a/mm/swap.c b/mm/swap.c index 6b697d33fa5b..7b1d3144391b 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -1012,6 +1012,8 @@ 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);
