[RFC PATCH 03/10] mm/damon/core: add damon_del_region() debug_sanity check

[SeongJae Park <sj@kernel.org>]

damon_del_region() should be called for targets that have one or more
regions.  Add a sanity check for that under CONFIG_DAMON_DEBUG_SANITY.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/core.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index a7f5748c1fe17..7e03c3af03694 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -158,8 +158,25 @@ void damon_add_region(struct damon_region *r, struct damon_target *t)
 	t->nr_regions++;
 }
 
+#ifdef CONFIG_DAMON_DEBUG_SANITY
+static void damon_verify_del_region(struct damon_target *t)
+{
+	if (t->nr_regions > 0)
+		return;
+	pr_err("damon_del_region() called while t->nr_regions <= 0 (%u)\n",
+			t->nr_regions);
+	WARN_ONCE();
+}
+#else
+static void damon_verify_del_region(struct damon_target *t)
+{
+}
+#endif
+
 static void damon_del_region(struct damon_region *r, struct damon_target *t)
 {
+	damon_verify_del_region(t);
+
 	list_del(&r->list);
 	t->nr_regions--;
 }
-- 
2.47.3