The previous commit moved from O(n) to O(1) for removal, but in the
process introduced an additional pointer member to a struct that
increased the size from 60 to 68 bytes, putting nodes in the 128-byte
slab. With deployed systems having as many as 2 million nodes, this
represents a significant doubling in memory usage (128 MiB -> 256 MiB).
Fix this by using our own kmem_cache, that's sized exactly right. This
also makes wireguard's memory usage more transparent in tools like
slabtop and /proc/slabinfo.
Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
---
drivers/net/wireguard/allowedips.c | 31 ++++++++++++++++++++++++------
drivers/net/wireguard/allowedips.h | 5 ++++-
drivers/net/wireguard/main.c | 10 +++++++++-
3 files changed, 38 insertions(+), 8 deletions(-)
diff --git a/drivers/net/wireguard/allowedips.c b/drivers/net/wireguard/allowedips.c
index 2785cfd3a221..c540dce8d224 100644
--- a/drivers/net/wireguard/allowedips.c
+++ b/drivers/net/wireguard/allowedips.c
@@ -6,6 +6,8 @@
#include "allowedips.h"
#include "peer.h"
+static struct kmem_cache *node_cache;
+
static void swap_endian(u8 *dst, const u8 *src, u8 bits)
{
if (bits == 32) {
@@ -40,6 +42,11 @@ static void push_rcu(struct allowedips_node **stack,
}
}
+static void node_free_rcu(struct rcu_head *rcu)
+{
+ kmem_cache_free(node_cache, container_of(rcu, struct allowedips_node, rcu));
+}
+
static void root_free_rcu(struct rcu_head *rcu)
{
struct allowedips_node *node, *stack[128] = {
@@ -49,7 +56,7 @@ static void root_free_rcu(struct rcu_head *rcu)
while (len > 0 && (node = stack[--len])) {
push_rcu(stack, node->bit[0], &len);
push_rcu(stack, node->bit[1], &len);
- kfree(node);
+ kmem_cache_free(node_cache, node);
}
}
@@ -164,7 +171,7 @@ static int add(struct allowedips_node __rcu **trie, u8 bits, const u8 *key,
return -EINVAL;
if (!rcu_access_pointer(*trie)) {
- node = kzalloc(sizeof(*node), GFP_KERNEL);
+ node = kmem_cache_zalloc(node_cache, GFP_KERNEL);
if (unlikely(!node))
return -ENOMEM;
RCU_INIT_POINTER(node->peer, peer);
@@ -180,7 +187,7 @@ static int add(struct allowedips_node __rcu **trie, u8 bits, const u8 *key,
return 0;
}
- newnode = kzalloc(sizeof(*newnode), GFP_KERNEL);
+ newnode = kmem_cache_zalloc(node_cache, GFP_KERNEL);
if (unlikely(!newnode))
return -ENOMEM;
RCU_INIT_POINTER(newnode->peer, peer);
@@ -213,10 +220,10 @@ static int add(struct allowedips_node __rcu **trie, u8 bits, const u8 *key,
return 0;
}
- node = kzalloc(sizeof(*node), GFP_KERNEL);
+ node = kmem_cache_zalloc(node_cache, GFP_KERNEL);
if (unlikely(!node)) {
list_del(&newnode->peer_list);
- kfree(newnode);
+ kmem_cache_free(node_cache, newnode);
return -ENOMEM;
}
INIT_LIST_HEAD(&node->peer_list);
@@ -306,7 +313,7 @@ void wg_allowedips_remove_by_peer(struct allowedips *table,
if (child)
child->parent_bit = node->parent_bit;
*rcu_dereference_protected(node->parent_bit, lockdep_is_held(lock)) = child;
- kfree_rcu(node, rcu);
+ call_rcu(&node->rcu, node_free_rcu);
/* TODO: Note that we currently don't walk up and down in order to
* free any potential filler nodes. This means that this function
@@ -350,4 +357,16 @@ struct wg_peer *wg_allowedips_lookup_src(struct allowedips *table,
return NULL;
}
+int __init wg_allowedips_slab_init(void)
+{
+ node_cache = KMEM_CACHE(allowedips_node, 0);
+ return node_cache ? 0 : -ENOMEM;
+}
+
+void wg_allowedips_slab_uninit(void)
+{
+ rcu_barrier();
+ kmem_cache_destroy(node_cache);
+}
+
#include "selftest/allowedips.c"
diff --git a/drivers/net/wireguard/allowedips.h b/drivers/net/wireguard/allowedips.h
index f08f552e6852..32d611aaf3cc 100644
--- a/drivers/net/wireguard/allowedips.h
+++ b/drivers/net/wireguard/allowedips.h
@@ -19,7 +19,7 @@ struct allowedips_node {
u8 bits[16] __aligned(__alignof(u64));
/* Keep rarely used members at bottom to be beyond cache line. */
- struct allowedips_node *__rcu *parent_bit; /* XXX: this puts us at 68->128 bytes instead of 60->64 bytes!! */
+ struct allowedips_node *__rcu *parent_bit;
union {
struct list_head peer_list;
struct rcu_head rcu;
@@ -53,4 +53,7 @@ struct wg_peer *wg_allowedips_lookup_src(struct allowedips *table,
bool wg_allowedips_selftest(void);
#endif
+int wg_allowedips_slab_init(void);
+void wg_allowedips_slab_uninit(void);
+
#endif /* _WG_ALLOWEDIPS_H */
diff --git a/drivers/net/wireguard/main.c b/drivers/net/wireguard/main.c
index 0a3ebfdac794..75dbe77b0b4b 100644
--- a/drivers/net/wireguard/main.c
+++ b/drivers/net/wireguard/main.c
@@ -21,10 +21,15 @@ static int __init mod_init(void)
{
int ret;
+ ret = wg_allowedips_slab_init();
+ if (ret < 0)
+ goto err_allowedips;
+
#ifdef DEBUG
+ ret = -ENOTRECOVERABLE;
if (!wg_allowedips_selftest() || !wg_packet_counter_selftest() ||
!wg_ratelimiter_selftest())
- return -ENOTRECOVERABLE;
+ goto err_peer;
#endif
wg_noise_init();
@@ -50,6 +55,8 @@ static int __init mod_init(void)
err_device:
wg_peer_uninit();
err_peer:
+ wg_allowedips_slab_uninit();
+err_allowedips:
return ret;
}
@@ -58,6 +65,7 @@ static void __exit mod_exit(void)
wg_genetlink_uninit();
wg_device_uninit();
wg_peer_uninit();
+ wg_allowedips_slab_uninit();
}
module_init(mod_init);
--
2.31.1
