[v2,38/46] mm: Add folio_evictable()

Commit Message

Matthew Wilcox June 22, 2021, 12:15 p.m. UTC

This is the folio equivalent of page_evictable().  Unfortunately, it's
different from !folio_unevictable(), but I think it's used in places
where you have to be a VM expert and can reasonably be expected to know
the difference.

Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
---
 mm/internal.h | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

Comments

Christoph Hellwig June 23, 2021, 9:54 a.m. UTC | #1

> + * Reasons folio might not be evictable:
> + * 1. page's mapping marked unevictable
> + * 2. page is part of an mlocked VMA

s/page/folio/?

Otherwise looks good:

Reviewed-by: Christoph Hellwig <[e-mail]>

Matthew Wilcox June 24, 2021, 11:50 p.m. UTC | #2

On Wed, Jun 23, 2021 at 11:54:06AM +0200, Christoph Hellwig wrote:
> > + * Reasons folio might not be evictable:
> > + * 1. page's mapping marked unevictable
> > + * 2. page is part of an mlocked VMA
> 
> s/page/folio/?

Thanks.

 * Reasons folio might not be evictable:
 * 1. folio's mapping marked unevictable
 * 2. One of the pages in the folio is part of an mlocked VMA

> Otherwise looks good:
> 
> Reviewed-by: Christoph Hellwig <[e-mail]>

Patch

diff --git a/mm/internal.h b/mm/internal.h
index d7013df5d1f0..3b0ab6b5457c 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -72,17 +72,28 @@  unsigned find_lock_entries(struct address_space *mapping, pgoff_t start,
 		pgoff_t end, struct pagevec *pvec, pgoff_t *indices);
 
 /**
- * page_evictable - test whether a page is evictable
- * @page: the page to test
+ * folio_evictable - Test whether a folio is evictable.
+ * @folio: The folio to test.
  *
- * Test whether page is evictable--i.e., should be placed on active/inactive
- * lists vs unevictable list.
- *
- * Reasons page might not be evictable:
- * (1) page's mapping marked unevictable
- * (2) page is part of an mlocked VMA
+ * Test whether @folio is evictable -- i.e., should be placed on
+ * active/inactive lists vs unevictable list.
  *
+ * Reasons folio might not be evictable:
+ * 1. page's mapping marked unevictable
+ * 2. page is part of an mlocked VMA
  */
+static inline bool folio_evictable(struct folio *folio)
+{
+	bool ret;
+
+	/* Prevent address_space of inode and swap cache from being freed */
+	rcu_read_lock();
+	ret = !mapping_unevictable(folio_mapping(folio)) &&
+			!folio_mlocked(folio);
+	rcu_read_unlock();
+	return ret;
+}
+
 static inline bool page_evictable(struct page *page)
 {
 	bool ret;