This will allow to use generic refcount_t interfaces to check counters overflow instead of currently existing VM_BUG_ON(). The only difference after the patch is VM_BUG_ON() may cause BUG(), while refcount_t fires with WARN(). But this seems not to be significant here, since such the problems are usually caught by syzbot with panic-on-warn enabled.
Signed-off-by: Kirill Tkhai <[email protected]> --- include/linux/memcontrol.h | 2 +- mm/memcontrol.c | 10 ++++------ 2 files changed, 5 insertions(+), 7 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 4399cc3f00e4..7ab2120155a4 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -78,7 +78,7 @@ struct mem_cgroup_reclaim_cookie { struct mem_cgroup_id { int id; - atomic_t ref; + refcount_t ref; }; /* diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 7bebe2ddec05..aa728d5b3d72 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4299,14 +4299,12 @@ static void mem_cgroup_id_remove(struct mem_cgroup *memcg) static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n) { - VM_BUG_ON(atomic_read(&memcg->id.ref) <= 0); - atomic_add(n, &memcg->id.ref); + refcount_add(n, &memcg->id.ref); } static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n) { - VM_BUG_ON(atomic_read(&memcg->id.ref) < n); - if (atomic_sub_and_test(n, &memcg->id.ref)) { + if (refcount_sub_and_test(n, &memcg->id.ref)) { mem_cgroup_id_remove(memcg); /* Memcg ID pins CSS */ @@ -4523,7 +4521,7 @@ static int mem_cgroup_css_online(struct cgroup_subsys_state *css) } /* Online state pins memcg ID, memcg ID pins CSS */ - atomic_set(&memcg->id.ref, 1); + refcount_set(&memcg->id.ref, 1); css_get(css); return 0; } @@ -6357,7 +6355,7 @@ subsys_initcall(mem_cgroup_init); #ifdef CONFIG_MEMCG_SWAP static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg) { - while (!atomic_inc_not_zero(&memcg->id.ref)) { + while (!refcount_inc_not_zero(&memcg->id.ref)) { /* * The root cgroup cannot be destroyed, so it's refcount must * always be >= 1.
