Hi Dan,
On 2023/9/28 21:03, Dan Carpenter wrote:
Hello Qi Zheng,
The patch b6884b5f15cf: "mm: shrinker: add a secondary array for
shrinker_info::{map, nr_deferred}" from Sep 11, 2023 (linux-next),
leads to the following Smatch static checker warning:
mm/shrinker.c:100 alloc_shrinker_info()
warn: inconsistent returns '&shrinker_mutex'.
mm/shrinker.c
77 int alloc_shrinker_info(struct mem_cgroup *memcg)
78 {
79 struct shrinker_info *info;
80 int nid, ret = 0;
81 int array_size = 0;
82
83 mutex_lock(&shrinker_mutex);
84 array_size = shrinker_unit_size(shrinker_nr_max);
85 for_each_node(nid) {
86 info = kvzalloc_node(sizeof(*info) + array_size, GFP_KERNEL, nid);
87 if (!info)
88 goto err;
^^^^^^^^^
89 info->map_nr_max = shrinker_nr_max;
90 if (shrinker_unit_alloc(info, NULL, nid))
91 goto err;
^^^^^^^^
These error paths need to unlock. I'm not 100% positive if you want to
unlock before or after the call to free_shrinker_info().
Thanks for reporting this. The shrinker_mutex should be unlocked before
the call to free_shrinker_info(). I will send a fix patch ASAP.
Thanks,
Qi
92 rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, info);
93 }
94 mutex_unlock(&shrinker_mutex);
95
96 return ret;
97
98 err:
99 free_shrinker_info(memcg);
-->100 return -ENOMEM;
101 }
regards,
dan carpenter
