diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 4bed78e47347..9b08d792fa95 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -275,7 +275,11 @@ struct bpf_map { */ atomic64_t refcnt ____cacheline_aligned; atomic64_t usercnt; - struct work_struct work; + /* rcu is used before freeing and work is only used during freeing */ + union { + struct work_struct work; + struct rcu_head rcu; + }; struct mutex freeze_mutex; atomic64_t writecnt; /* 'Ownership' of program-containing map is claimed by the first program @@ -291,6 +295,7 @@ struct bpf_map { } owner; bool bypass_spec_v1; bool frozen; /* write-once; write-protected by freeze_mutex */ + bool free_after_mult_rcu_gp; s64 __percpu *elem_count; }; diff --git a/kernel/bpf/map_in_map.c b/kernel/bpf/map_in_map.c index 2dfeb5835e16..3248ff5d8161 100644 --- a/kernel/bpf/map_in_map.c +++ b/kernel/bpf/map_in_map.c @@ -129,10 +129,15 @@ void *bpf_map_fd_get_ptr(struct bpf_map *map, void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer) { - /* ptr->ops->map_free() has to go through one - * rcu grace period by itself. + struct bpf_map *inner_map = ptr; + + /* The inner map may still be used by both non-sleepable and sleepable + * bpf program, so free it after one RCU grace period and one tasks + * trace RCU grace period. */ - bpf_map_put(ptr); + if (need_defer) + WRITE_ONCE(inner_map->free_after_mult_rcu_gp, true); + bpf_map_put(inner_map); } u32 bpf_map_fd_sys_lookup_elem(void *ptr) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index d77b2f8b9364..1625b9d5202c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -717,6 +717,28 @@ static void bpf_map_put_uref(struct bpf_map *map) } } +static void bpf_map_free_in_work(struct bpf_map *map) +{ + INIT_WORK(&map->work, bpf_map_free_deferred); + /* Avoid spawning kworkers, since they all might contend + * for the same mutex like slab_mutex. + */ + queue_work(system_unbound_wq, &map->work); +} + +static void bpf_map_free_rcu_gp(struct rcu_head *rcu) +{ + bpf_map_free_in_work(container_of(rcu, struct bpf_map, rcu)); +} + +static void bpf_map_free_mult_rcu_gp(struct rcu_head *rcu) +{ + if (rcu_trace_implies_rcu_gp()) + bpf_map_free_rcu_gp(rcu); + else + call_rcu(rcu, bpf_map_free_rcu_gp); +} + /* decrement map refcnt and schedule it for freeing via workqueue * (underlying map implementation ops->map_free() might sleep) */ @@ -726,11 +748,11 @@ void bpf_map_put(struct bpf_map *map) /* bpf_map_free_id() must be called first */ bpf_map_free_id(map); btf_put(map->btf); - INIT_WORK(&map->work, bpf_map_free_deferred); - /* Avoid spawning kworkers, since they all might contend - * for the same mutex like slab_mutex. - */ - queue_work(system_unbound_wq, &map->work); + + if (READ_ONCE(map->free_after_mult_rcu_gp)) + call_rcu_tasks_trace(&map->rcu, bpf_map_free_mult_rcu_gp); + else + bpf_map_free_in_work(map); } } EXPORT_SYMBOL_GPL(bpf_map_put);