mm: remove folio from deferred split list before uncharging it

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/[email protected]/
Link: https://lkml.kernel.org/r/[email protected]
Fixes: f77171d (mm: allow non-hugetlb large folios to be batch processed)
Fixes: 29f3843 (mm: free folios directly in move_folios_to_lru())
Fixes: bc2ff4c (mm: free folios in a batch in shrink_folio_list())
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Debugged-by: Ryan Roberts <[email protected]>
Tested-by: Ryan Roberts <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Matthew Wilcox (Oracle)

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);
 

mm/vmscan.c

@@ -1413,6 +1413,9 @@ 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();
@@ -1819,6 +1822,9 @@ 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);