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.

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 --- samples/damon/mtier.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

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; }