From: Kairui Song Replace free_folio_and_swap_cache() with an explicit folio_free_swap() and folio_put() in the after-split loop. free_folio_and_swap_cache() unlocks the folio, then free_swap_cache() must trylock it again and re-check folio_mapped() before freeing the swap cache entries; if the trylock loses a race, the entries are left behind even though the folio reference is dropped. The sub folios are still locked and unmapped here, so just directly call folio_free_swap() under the lock, unlock and drop the reference. This makes the swap cache freeing deterministic and the reference drop explicit. Reviewed-by: Zi Yan Reviewed-by: Yeoreum Yun Signed-off-by: Kairui Song --- mm/huge_memory.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 6ce58a5d93d8..f2862556d715 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -4300,7 +4300,8 @@ static int __folio_split(struct folio *folio, unsigned int new_order, struct list_head *list, enum split_type split_type) { struct folio *end_folio = folio_next(folio); - bool is_anon = folio_test_anon(folio); + const bool is_anon = folio_test_anon(folio); + const bool is_swapcache = folio_test_swapcache(folio); int old_order = folio_order(folio); struct folio *new_folio, *next; int ret; @@ -4340,14 +4341,16 @@ static int __folio_split(struct folio *folio, unsigned int new_order, if (new_folio == page_folio(lock_at)) continue; - folio_unlock(new_folio); /* * Subpages whose mapping has been zapped may be freed * earlier, but freeing them requires taking the - * lru_lock, so we defer put_page() on tail pages until + * lru_lock, so we defer folio_put() on tail pages until * after the split completes. */ - free_folio_and_swap_cache(new_folio); + if (is_swapcache && !folio_mapped(new_folio)) + folio_free_swap(new_folio); + folio_unlock(new_folio); + folio_put(new_folio); } out: @@ -4374,7 +4377,7 @@ static int __folio_split(struct folio *folio, unsigned int new_order, * isolated from LRU (if applicable) * * Upon return, the folio is not remapped, split folios are not added to LRU, - * free_folio_and_swap_cache() is not called, and new folios remain locked. + * folio_free_swap() is not called, and new folios remain locked. * * Return: 0 on success, -EAGAIN if the folio cannot be split (e.g., due to * insufficient reference count or extra pins). -- 2.55.0