The function for allocating and initialize a 'struct damos' object,
damon_new_scheme(), is not initializing damos->walk_completed field.
Only damos_walk_complete() is setting the field. Hence the field will
be eventually set and used correctly from second damos_walk() call for
the scheme. But the first damos_walk() could mistakenly not walk on the
regions. Actually, a common usage of DAMOS for taking an access pattern
snapshot is installing a monitoring-purpose DAMOS scheme, doing
damos_walk() to retrieve the snapshot, and then removing the scheme.
DAMON user-space tool (damo) also gets runtime snapshot in the way.
Hence the problem can continuously happen in such use cases. Initialize
it properly in the allocation function.
Fixes: bf0eaba0ff9c ("mm/damon/core: implement damos_walk()")
Cc: <stable@xxxxxxxxxxxxxxx> # 6.14.x
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
mm/damon/core.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 38f545fea585..cfa105ee9610 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -373,6 +373,7 @@ struct damos *damon_new_scheme(struct damos_access_pattern *pattern,
* or damon_attrs are updated.
*/
scheme->next_apply_sis = 0;
+ scheme->walk_completed = false;
INIT_LIST_HEAD(&scheme->filters);
scheme->stat = (struct damos_stat){};
INIT_LIST_HEAD(&scheme->list);
base-commit: 3880bbe477938a3b30ff7bf2ef316adf98876671
--
2.39.5
