[RFC PATCH 6.6.y 1/2] mm/damon/sysfs: put target pids for damon_start() failure

[SJ Park <sj@kernel.org>]

damon_sysfs_turn_damon_on() allocates and sets up damon_ctx to start.
If it is for virtual address space monitoring, the setup increases the
reference counts of the target pids.  After the setup, the function
invokes damon_start().  If damon_start() fails, it deallocates the
damon_ctx object without decreasing the reference counts of target pids.
As a result, pids can be leaked.

Fix the leak by putting pids using damon_sysfs_destroy_targets() before
deallocating the damon_ctx object.

Fixes: a61ea561c871 ("mm/damon/sysfs: link DAMON for virtual address spaces monitoring")
Cc: <stable@vger.kernel.org> # 5.18.x
Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/sysfs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 46980a4bef23a..d95fda1054a00 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1465,6 +1465,7 @@ static int damon_sysfs_turn_damon_on(struct damon_sysfs_kdamond *kdamond)
 		return PTR_ERR(ctx);
 	err = damon_start(&ctx, 1, false);
 	if (err) {
+		damon_sysfs_destroy_targets(ctx);
 		damon_destroy_ctx(ctx);
 		return err;
 	}
-- 
2.47.3