From: Pu Lehui pulehui@huawei.com

Commit 70294d8bc31f ("bpf: Eliminate rlimit-based memory accounting for devmap maps") relies on the v5.11+ basic mechanism of memcg-based memory accounting [0]. The commit cannot be independently backported to the 5.10 stable branch, otherwise the related memory when creating devmap will be unrestricted and the associated bpf selftest map_ptr will fail. Let's roll back to rlimit-based memory accounting mode for devmap and re-adapt the commit 225da02acdc9 ("bpf: Fix DEVMAP_HASH overflow check on 32-bit arches") to the 5.10 stable branch.

Link: https://lore.kernel.org/bpf/20201201215900.3569844-1-guro@fb.com [0] Fixes: 225da02acdc9 ("bpf: Fix DEVMAP_HASH overflow check on 32-bit arches") Fixes: 70294d8bc31f ("bpf: Eliminate rlimit-based memory accounting for devmap maps") Signed-off-by: Pu Lehui pulehui@huawei.com --- kernel/bpf/devmap.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index 07b5edb2c70f..7eb1282edc8e 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -109,6 +109,8 @@ static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab, static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr) { u32 valsize = attr->value_size; + u64 cost = 0; + int err;

/* check sanity of attributes. 2 value sizes supported: * 4 bytes: ifindex @@ -136,11 +138,21 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr) return -EINVAL;

dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries); + cost += (u64) sizeof(struct hlist_head) * dtab->n_buckets; + } else { + cost += (u64) dtab->map.max_entries * sizeof(struct bpf_dtab_netdev *); + }

+ /* if map size is larger than memlock limit, reject it */ + err = bpf_map_charge_init(&dtab->map.memory, cost); + if (err) + return -EINVAL; + + if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) { dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets, dtab->map.numa_node); if (!dtab->dev_index_head) - return -ENOMEM; + goto free_charge;

spin_lock_init(&dtab->index_lock); } else { @@ -148,10 +160,14 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr) sizeof(struct bpf_dtab_netdev *), dtab->map.numa_node); if (!dtab->netdev_map) - return -ENOMEM; + goto free_charge; }

return 0; + +free_charge: + bpf_map_charge_finish(&dtab->map.memory); + return -ENOMEM; }

static struct bpf_map *dev_map_alloc(union bpf_attr *attr)