damon/sysfs: Fix possible memleak on damon_sysfs_add_target.

When damon_sysfs_add_target couldn't find proper task, New allocated damon_target structure isn't registered yet, So, it's impossible to free new allocated one by damon_sysfs_destroy_targets.

By calling daemon_add_target as soon as allocating new target, Fix this possible memory leak.

---
 mm/damon/sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 7488e27c87c3..bdef9682d0a0 100644
@@ -2182,12 +2182,12 @@ static int damon_sysfs_add_target(struct damon_sysfs_target *sys_target,
 
 	if (!t)
 		return -ENOMEM;
+	damon_add_target(ctx, t);
 	if (damon_target_has_pid(ctx)) {
 		t->pid = find_get_pid(sys_target->pid);
 		if (!t->pid)
 			goto destroy_targets_out;
 	}
-	damon_add_target(ctx, t);
 	err = damon_sysfs_set_regions(t, sys_target->regions);
 	if (err)
 		goto destroy_targets_out;

2.35.1

Hi Levi,

The commit is indeed the last one which touched the code, but the bug was introduced earlier than that, by commit a61ea561c871 ("mm/damon/sysfs: link DAMON for virtual address spaces monitoring").

Also, let's add one space before the commit hash, then only 12 characters for the hash, and then one line summary of the commit[1], like below.

[1] https://www.kernel.org/doc/html/v4.15/process/submitting-patches.html#describe-your-changes

Also, putting the change log of the patch here would be a good practice.

Other than the very minor things,

As the changes I'm requesting are very minor, I will revise and post a new version of this patch on my own.

Thanks,
SJ