On Wed, Sep 22, 2021 at 11:08:58AM -0400, Johannes Weiner wrote: > mm/memcg: Add folio_memcg() and related functions > mm/memcg: Convert commit_charge() to take a folio > mm/memcg: Convert mem_cgroup_charge() to take a folio > mm/memcg: Convert uncharge_page() to uncharge_folio() > mm/memcg: Convert mem_cgroup_uncharge() to take a folio > mm/memcg: Convert mem_cgroup_migrate() to take folios > mm/memcg: Convert mem_cgroup_track_foreign_dirty_slowpath() to folio > mm/memcg: Add folio_memcg_lock() and folio_memcg_unlock() > mm/memcg: Convert mem_cgroup_move_account() to use a folio > mm/memcg: Add folio_lruvec() > mm/memcg: Add folio_lruvec_lock() and similar functions > mm/memcg: Add folio_lruvec_relock_irq() and folio_lruvec_relock_irqsave() > mm/workingset: Convert workingset_activation to take a folio > > This is all anon+file stuff, not needed for filesystem > folios. No, that's not true. A number of these functions are called from filesystem code. mem_cgroup_track_foreign_dirty() is only called from filesystem code. We at the very least need wrappers like folio_cgroup_charge(), and folio_memcg_lock(). > As per the other email, no conceptual entry point for > tail pages into either subsystem, so no ambiguity > around the necessity of any compound_head() calls, > directly or indirectly. It's easy to rule out > wholesale, so there is no justification for > incrementally annotating every single use of the page. The justification is that we can remove all those hidden calls to compound_head(). Hundreds of bytes of text spread throughout this file. > mm: Add folio_young and folio_idle > mm/swap: Add folio_activate() > mm/swap: Add folio_mark_accessed() > > This is anon+file aging stuff, not needed. Again, very much needed. Take a look at pagecache_get_page(). In Linus' tree today, it calls if (page_is_idle(page)) clear_page_idle(page); So either we need wrappers (which are needlessly complicated thanks to how page_is_idle() is defined) or we just convert it. > mm/rmap: Add folio_mkclean() > > mm/migrate: Add folio_migrate_mapping() > mm/migrate: Add folio_migrate_flags() > mm/migrate: Add folio_migrate_copy() > > More anon+file conversion, not needed. As far as I can tell, anon never calls any of these three functions. anon calls migrate_page(), which calls migrate_page_move_mapping(), but several filesystems do call these individual functions. > mm/lru: Add folio_add_lru() > > LRU code, not needed. Again, we need folio_add_lru() for filemap. This one's more tractable as a wrapper function.
