[PATCH] mm/damon/core: fix memory leak of repeat mode damon_call_control objects

[Enze Li <lienze@kylinos.cn>]

A memory leak exists in the handling of repeat mode damon_call_control
objects by kdamond_call().  While damon_call() correctly allows multiple
repeat mode objects (with ->repeat set to true) to be added to the
per-context list, kdamond_call() incorrectly processes them.

The function moves all repeat mode objects from the context's list to a
temporary list (repeat_controls).  However, it only moves the first
object back to the context's list for future calls, leaving the
remaining objects on the temporary list where they are abandoned and
leaked.

This patch fixes the leak by ensuring all repeat mode objects are
properly re-added to the context's list.

Fixes: 43df7676e550 ("mm/damon/core: introduce repeat mode damon_call()")
Signed-off-by: Enze Li <lienze@kylinos.cn>
Cc: <stable@vger.kernel.org> # 6.17.x
---
 mm/damon/core.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 109b050c795a..66b5bae44f22 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -2526,13 +2526,19 @@ static void kdamond_call(struct damon_ctx *ctx, bool cancel)
 			list_add(&control->list, &repeat_controls);
 		}
 	}
-	control = list_first_entry_or_null(&repeat_controls,
-			struct damon_call_control, list);
-	if (!control || cancel)
-		return;
-	mutex_lock(&ctx->call_controls_lock);
-	list_add_tail(&control->list, &ctx->call_controls);
-	mutex_unlock(&ctx->call_controls_lock);
+	while (true) {
+		control = list_first_entry_or_null(&repeat_controls,
+				struct damon_call_control, list);
+		if (!control)
+			break;
+		/* Unlink from the repeate_controls list. */
+		list_del(&control->list);
+		if (cancel)
+			continue;
+		mutex_lock(&ctx->call_controls_lock);
+		list_add(&control->list, &ctx->call_controls);
+		mutex_unlock(&ctx->call_controls_lock);
+	}
 }
 
 /* Returns negative error code if it's not activated but should return */

base-commit: 7d0a66e4bb9081d75c82ec4957c50034cb0ea449
-- 
2.52.0