diff options
| author | Shakeel Butt <shakeel.butt@linux.dev> | 2025-12-24 16:29:04 -0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-01-14 22:16:21 -0800 |
| commit | a38be546269073bf8edc3c49eaf18cdfce905777 (patch) | |
| tree | eafc373d4320d2cd347ff43e08ec8073cfb34c20 | |
| parent | 582f0f3864110e1c6e4af3af768e1c2453ba2306 (diff) | |
mm/damon/core: get memcg reference before access
The commit b74a120bcf507 ("mm/damon/core: implement
DAMOS_QUOTA_NODE_MEMCG_USED_BP") added accesses to memcg structure without
getting reference to it. This is unsafe. Let's get the reference before
accessing the memcg.
Link: https://lkml.kernel.org/r/20251225002904.139543-1-shakeel.butt@linux.dev
Fixes: b74a120bcf507 ("mm/damon/core: implement DAMOS_QUOTA_NODE_MEMCG_USED_BP")
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/damon/core.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/mm/damon/core.c b/mm/damon/core.c index f9fc0375890a..fd09bd106ad5 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2051,13 +2051,15 @@ static unsigned long damos_get_node_memcg_used_bp( rcu_read_lock(); memcg = mem_cgroup_from_id(goal->memcg_id); - rcu_read_unlock(); - if (!memcg) { + if (!memcg || !mem_cgroup_tryget(memcg)) { + rcu_read_unlock(); if (goal->metric == DAMOS_QUOTA_NODE_MEMCG_USED_BP) return 0; else /* DAMOS_QUOTA_NODE_MEMCG_FREE_BP */ return 10000; } + rcu_read_unlock(); + mem_cgroup_flush_stats(memcg); lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(goal->nid)); used_pages = lruvec_page_state(lruvec, NR_ACTIVE_ANON); @@ -2065,6 +2067,8 @@ static unsigned long damos_get_node_memcg_used_bp( used_pages += lruvec_page_state(lruvec, NR_ACTIVE_FILE); used_pages += lruvec_page_state(lruvec, NR_INACTIVE_FILE); + mem_cgroup_put(memcg); + si_meminfo_node(&i, goal->nid); if (goal->metric == DAMOS_QUOTA_NODE_MEMCG_USED_BP) numerator = used_pages; |