quoted

---
  include/linux/page-flags.h |  6 ------
  mm/migrate.c               | 43 ++++++++++++--------------------------
  mm/vmscan.c                |  6 ++++--
  3 files changed, 17 insertions(+), 38 deletions(-)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index c67163b73c5ec..4c27ebb689e3c 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h

@@ -744,12 +744,6 @@ static __always_inline bool PageAnon(const struct page *page)
  	return folio_test_anon(page_folio(page));
  }

-static __always_inline bool __folio_test_movable(const struct folio *folio)
-{
-	return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
-			PAGE_MAPPING_MOVABLE;
-}
-

Woah, wait, does this mean we can remove PAGE_MAPPING_MOVABLE??

Jup :)

Nice!

quoted

  static __always_inline bool page_has_movable_ops(const struct page *page)
  {
  	return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==

diff --git a/mm/migrate.c b/mm/migrate.c
index 587af35b7390d..15d3c1031530c 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c

@@ -219,12 +219,7 @@ void putback_movable_pages(struct list_head *l)
  			continue;
  		}
  		list_del(&folio->lru);
-		/*
-		 * We isolated non-lru movable folio so here we can use
-		 * __folio_test_movable because LRU folio's mapping cannot
-		 * have PAGE_MAPPING_MOVABLE.
-		 */

So hate these references to 'LRU' as in meaning 'pages that could be on the
LRU'.

Yeah, it's a historical thing.

But for anything we isolated, it had to be an LRU folio (PageLRU) 
because that's how we were even able to isolate it ... from the LRU.

[...]

quoted

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 098bcc821fc74..103dfc729a823 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c

@@ -1658,9 +1658,11 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
  	unsigned int noreclaim_flag;

  	list_for_each_entry_safe(folio, next, folio_list, lru) {
+		/* TODO: these pages should not even appear in this list. */
+		if (page_has_movable_ops(&folio->page))

VM_WARN_ON_ONCE()?

Well, no, it can currently still happen. But really, movable_ops pages 
are not folios that could ever be reclaimed that way.

So the TODO highlights that movable_ops pages should never even be put 
in a list (page->lru will go away).

-- 
Cheers,

David / dhildenb