linux-kernel - [PATCH 1/2] mm/damon/core: introduce damon_call_control->dealloc_on

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Message-Id: <20250908201513.60802-2-sj@kernel.org>
Date: Mon,  8 Sep 2025 13:15:12 -0700
From: SeongJae Park <sj@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: SeongJae Park <sj@...nel.org>,
	Yunjeong Mun <yunjeong.mun@...com>,
	damon@...ts.linux.dev,
	kernel-team@...a.com,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [PATCH 1/2] mm/damon/core: introduce damon_call_control->dealloc_on_cancel

When damon_call_control->repeat is set, damon_call() is executed
asynchronously, and eventually be canceled when kdamond finishes.  If
the damon_call_control object is dynamically allocated, hence, finding
the place to deallocate the object is difficult.  Introduce a new
damon_call_control field, namely dealloc_on_cancel, to ask the kdamond
deallocates those dynamically allocated objects when those are canceled.

Signed-off-by: SeongJae Park <sj@...nel.org>
---
 include/linux/damon.h | 2 ++
 mm/damon/core.c       | 8 ++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index ec8716292c09..aa7381be388c 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -636,6 +636,7 @@ struct damon_operations {
  * @data:		Data that will be passed to @fn.
  * @repeat:		Repeat invocations.
  * @return_code:	Return code from @fn invocation.
+ * @dealloc_on_cancel:	De-allocate when canceled.
  *
  * Control damon_call(), which requests specific kdamond to invoke a given
  * function.  Refer to damon_call() for more details.
@@ -645,6 +646,7 @@ struct damon_call_control {
 	void *data;
 	bool repeat;
 	int return_code;
+	bool dealloc_on_cancel;
 /* private: internal use only */
 	/* informs if the kdamond finished handling of the request */
 	struct completion completion;
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 7aeb3f24aae8..be5942435d78 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -2510,10 +2510,14 @@ static void kdamond_call(struct damon_ctx *ctx, bool cancel)
 		mutex_lock(&ctx->call_controls_lock);
 		list_del(&control->list);
 		mutex_unlock(&ctx->call_controls_lock);
-		if (!control->repeat)
+		if (!control->repeat) {
 			complete(&control->completion);
-		else
+		} else if (control->canceled && control->dealloc_on_cancel) {
+			kfree(control);
+			continue;
+		} else {
 			list_add(&control->list, &repeat_controls);
+		}
 	}
 	control = list_first_entry_or_null(&repeat_controls,
 			struct damon_call_control, list);
-- 
2.39.5