[RFC PATCH 2/6] mm/damon/vaddr: advance migration attempt in folio level for filter out

[SJ Park <sj@kernel.org>]

damos_va_migrate_pmd_entry() finds folios to migrate under the given
pmd, using a loop for the pmd address range.  The loop advances in page
size if a given folio is excluded by DAMOS ops filters.  DAMOS ops
filters work in folio granularity.  Hence it is more efficient and makes
sense to advance in the folio size.

Advance the loop in folio size for the ops filter out decision.  For
that, do the folio size based loop advancement offset update before
applying DAMOS ops filters.

Closes: https://sashiko.dev/#/bug/linux-67c34df7-6dfb-4e18-9ce0-0d26915e5785
Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/vaddr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index b549496ea8e2c..c271b6d63c027 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -881,12 +881,12 @@ static int damos_va_migrate_pmd_entry(pmd_t *pmd, unsigned long addr,
 		folio = vm_normal_folio(walk->vma, addr, ptent);
 		if (!folio)
 			continue;
+		page_idx = folio_page_idx(folio, pte_page(ptent));
+		nr = folio_nr_pages(folio) - page_idx;
 		if (damos_va_filter_out(s, folio, walk->vma, addr, pte, NULL))
 			continue;
 		damos_va_migrate_dests_add(folio, walk->vma, addr, dests,
 				migration_lists);
-		page_idx = folio_page_idx(folio, pte_page(ptent));
-		nr = folio_nr_pages(folio) - page_idx;
 	}
 	pte_unmap_unlock(start_pte, ptl);
 	return 0;
-- 
2.47.3