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]>
chewitt · Mar 12, 2024 · 47932e7 · 47932e7
1 parent 58f327f
commit 47932e7
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diff --git 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
@@ -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);