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@vger.kernel.org # 6.14.x Signed-off-by: SeongJae Park sj@kernel.org --- 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