The recently introduced PG_dropbehind allows for freeing folios
immediately after writeback. Unlike PG_reclaim, it does not need vmscan
to be involved to get the folio freed.
Instead of using folio_set_reclaim(), use folio_set_dropbehind() in
pageout().
It is safe to leave PG_dropbehind on the folio if, for some reason
(bug?), the folio is not in a writeback state after ->writepage().
In these cases, the kernel had to clear PG_reclaim as it shared a page
flag bit with PG_readahead.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
---
mm/vmscan.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index a099876fa029..d15f80333d6b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -692,19 +692,16 @@ static pageout_t pageout(struct folio *folio, struct address_space *mapping,
if (shmem_mapping(mapping) && folio_test_large(folio))
wbc.list = folio_list;
- folio_set_reclaim(folio);
+ folio_set_dropbehind(folio);
+
res = mapping->a_ops->writepage(&folio->page, &wbc);
if (res < 0)
handle_write_error(mapping, folio, res);
if (res == AOP_WRITEPAGE_ACTIVATE) {
- folio_clear_reclaim(folio);
+ folio_clear_dropbehind(folio);
return PAGE_ACTIVATE;
}
- if (!folio_test_writeback(folio)) {
- /* synchronous write or broken a_ops? */
- folio_clear_reclaim(folio);
- }
trace_mm_vmscan_write_folio(folio);
node_stat_add_folio(folio, NR_VMSCAN_WRITE);
return PAGE_SUCCESS;
--
2.45.2
