From: Honggyu Kim <honggyu.kim@sk.com>
Date: Wed, 2 Jul 2025 00:02:03 +0000 (+0900)
Subject: samples/damon: fix damon sample mtier for start failure
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=ddba1b6cf4791824f8b614ff8878353a6c6f79f5;p=linux-block.git

samples/damon: fix damon sample mtier for start failure

The damon_sample_mtier_start() can fail so we must reset the "enable"
parameter to "false" again for proper rollback.

In such cases, setting Y to "enable" then N triggers the similar crash
with mtier because damon sample start failed but the "enable" stays as Y.

Link: https://lkml.kernel.org/r/20250702000205.1921-4-honggyu.kim@sk.com
Fixes: 82a08bde3cf7 ("samples/damon: implement a DAMON module for memory tiering")
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/samples/damon/mtier.c b/samples/damon/mtier.c
index 36d2cd933f5a..c94254b77fc9 100644
--- a/samples/damon/mtier.c
+++ b/samples/damon/mtier.c
@@ -164,8 +164,12 @@ static int damon_sample_mtier_enable_store(
 	if (enable == enabled)
 		return 0;
 
-	if (enable)
-		return damon_sample_mtier_start();
+	if (enable) {
+		err = damon_sample_mtier_start();
+		if (err)
+			enable = false;
+		return err;
+	}
 	damon_sample_mtier_stop();
 	return 0;
 }