linux-kernel - [PATCH 2/4] mm/damon/paddr: do page level access check for pageout DAMOS action on its own

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Date: Mon, 29 Apr 2024 15:44:49 -0700
From: SeongJae Park <sj@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: SeongJae Park <sj@...nel.org>,
	damon@...ts.linux.dev,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] mm/damon/paddr: do page level access check for pageout DAMOS action on its own

'pageout' DAMOS action implementation of 'paddr' DAMON operations set
asks reclaim_pages() to do page level access check if the user is not
asking DAMOS to do that on its own.  Simplify the logic by making the
check always be done by 'paddr'.

Signed-off-by: SeongJae Park <sj@...nel.org>
---
 mm/damon/paddr.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index d5f2f7ddf863..974edef1740d 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -244,16 +244,22 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s)
 {
 	unsigned long addr, applied;
 	LIST_HEAD(folio_list);
-	bool ignore_references = false;
+	bool install_young_filter = true;
 	struct damos_filter *filter;
 
-	/* respect user's page level reference check handling request */
+	/* check access in page level again by default */
 	damos_for_each_filter(filter, s) {
 		if (filter->type == DAMOS_FILTER_TYPE_YOUNG) {
-			ignore_references = true;
+			install_young_filter = false;
 			break;
 		}
 	}
+	if (install_young_filter) {
+		filter = damos_new_filter(DAMOS_FILTER_TYPE_YOUNG, true);
+		if (!filter)
+			return 0;
+		damos_add_filter(s, filter);
+	}
 
 	for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) {
 		struct folio *folio = damon_get_folio(PHYS_PFN(addr));
@@ -275,7 +281,9 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s)
 put_folio:
 		folio_put(folio);
 	}
-	applied = reclaim_pages(&folio_list, ignore_references);
+	if (install_young_filter)
+		damos_destroy_filter(filter);
+	applied = reclaim_pages(&folio_list, true);
 	cond_resched();
 	return applied * PAGE_SIZE;
 }
-- 
2.39.2