From: NeilBrown Subject: mm: drop swap_dirty_folio folios that are written to swap are owned by the MM subsystem - not any filesystem. When such a folio is passed to a filesystem to be written out to a swap-file, the filesystem handles the data, but the folio itself does not belong to the filesystem. So calling the filesystem's ->dirty_folio() address_space operation makes no sense. This is for folios in the given address space, and a folio to be written to swap does not exist in the given address space. So drop swap_dirty_folio() which calls the address-space's ->dirty_folio(), and always use noop_dirty_folio(), which is appropriate for folios being swapped out. Link: https://lkml.kernel.org/r/164859778123.29473.6900942583784889976.stgit@noble.brown Signed-off-by: NeilBrown Reviewed-by: Christoph Hellwig Tested-by: David Howells Tested-by: Geert Uytterhoeven Cc: Hugh Dickins Cc: Mel Gorman Cc: Trond Myklebust Signed-off-by: Andrew Morton --- include/linux/swap.h | 1 - mm/page_io.c | 17 ----------------- mm/swap_state.c | 2 +- 3 files changed, 1 insertion(+), 19 deletions(-) --- a/include/linux/swap.h~mm-drop-swap_dirty_folio +++ a/include/linux/swap.h @@ -427,7 +427,6 @@ extern void kswapd_stop(int nid); #ifdef CONFIG_SWAP -bool swap_dirty_folio(struct address_space *mapping, struct folio *folio); int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, unsigned long nr_pages, sector_t start_block); int generic_swapfile_activate(struct swap_info_struct *, struct file *, --- a/mm/page_io.c~mm-drop-swap_dirty_folio +++ a/mm/page_io.c @@ -385,20 +385,3 @@ out: delayacct_swapin_end(); return ret; } - -bool swap_dirty_folio(struct address_space *mapping, struct folio *folio) -{ - struct swap_info_struct *sis = swp_swap_info(folio_swap_entry(folio)); - - if (data_race(sis->flags & SWP_FS_OPS)) { - const struct address_space_operations *aops; - - mapping = sis->swap_file->f_mapping; - aops = mapping->a_ops; - - VM_BUG_ON_FOLIO(!folio_test_swapcache(folio), folio); - return aops->dirty_folio(mapping, folio); - } else { - return noop_dirty_folio(mapping, folio); - } -} --- a/mm/swap_state.c~mm-drop-swap_dirty_folio +++ a/mm/swap_state.c @@ -31,7 +31,7 @@ */ static const struct address_space_operations swap_aops = { .writepage = swap_writepage, - .dirty_folio = swap_dirty_folio, + .dirty_folio = noop_dirty_folio, #ifdef CONFIG_MIGRATION .migratepage = migrate_page, #endif _