[5.10] bpf: Fix mismatch memory accounting for devmap maps

Commit Message

Pu Lehui Sept. 20, 2024, 10:39 a.m. UTC

From: Pu Lehui <[e-mail]>

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/[e-mail] [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 <[e-mail]>
---
 kernel/bpf/devmap.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

Patch

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)