[RFC PATCH 01/11] mm/damon/core: stop ctxs in damon_start() before returning an error

[SJ Park <sj@kernel.org>]

When multiple contexts are passed to damon_start(), the function starts
the contexts one by one.  If any of the operations fails, it immediately
returns an error.  Contexts that successfully started before the failure
keep running.  The caller should catch this and stop the contexts.  It
is complicated and easy to make mistakes.  Stop all contexts in
damon_start() under the failures.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 3c5a46e1c079a..16d9223c33a72 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1909,8 +1909,10 @@ int damon_start(struct damon_ctx **ctxs, int nr_ctxs, bool exclusive)
 
 	for (i = 0; i < nr_ctxs; i++) {
 		err = __damon_start(ctxs[i]);
-		if (err)
+		if (err) {
+			damon_stop(ctxs, i);
 			break;
+		}
 		nr_running_ctxs++;
 	}
 	if (exclusive && nr_running_ctxs)
-- 
2.47.3