linux-kernel - [PATCH 2/3] mm/damon/core: do not call damos_walk

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Message-Id: <20250210182737.134994-3-sj@kernel.org>
Date: Mon, 10 Feb 2025 10:27:35 -0800
From: SeongJae Park <sj@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: SeongJae Park <sj@...nel.org>,
	damon@...ts.linux.dev,
	kernel-team@...a.com,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [PATCH 2/3] mm/damon/core: do not call damos_walk_control->walk() if walk is completed

damos_walk() invokes callback functions of schemes until all schemes
finishes at least one round of walks.  If there are multiple DAMOS
schemes having different apply_interval, the callback functions for
longer apply interval scheme will be called for more than a round of the
walk.

The behavior is different from the document (see damos_walk() kernel-doc
comment), and not useful.  Make the behavior be same to the documented
one, by stopping invoking the callback if the walk for the given scheme
is completed.

Fixes: bf0eaba0ff9c ("mm/damon/core: implement damos_walk()")
Signed-off-by: SeongJae Park <sj@...nel.org>
---
 mm/damon/core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 1d9025d14d83..4b865b2558d9 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1453,6 +1453,9 @@ static void damos_walk_call_walk(struct damon_ctx *ctx, struct damon_target *t,
 {
 	struct damos_walk_control *control;

+	if (s->walk_completed)
+		return;
+
 	mutex_lock(&ctx->walk_control_lock);
 	control = ctx->walk_control;
 	mutex_unlock(&ctx->walk_control_lock);
-- 
2.39.5