netlink: use kvmalloc() in netlink_alloc_large_skb()
This is a followup of commit 234ec0b6034b ("netlink: fix potential
sleeping issue in mqueue_flush_file"), because vfree_atomic()
overhead is unfortunate for medium sized allocations.
1) If the allocation is smaller than PAGE_SIZE, do not bother
with vmalloc() at all. Some arches have 64KB PAGE_SIZE,
while NLMSG_GOODSIZE is smaller than 8KB.
2) Use kvmalloc(), which might allocate one high order page
instead of vmalloc if memory is not too fragmented.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Zhengchao Shao <shaozhengchao@huawei.com>
Link: https://lore.kernel.org/r/20240224090630.605917-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index be5792b..765921c 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1202,23 +1202,21 @@ struct sock *netlink_getsockbyfilp(struct file *filp)
struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast)
{
+ size_t head_size = SKB_HEAD_ALIGN(size);
struct sk_buff *skb;
void *data;
- if (size <= NLMSG_GOODSIZE || broadcast)
+ if (head_size <= PAGE_SIZE || broadcast)
return alloc_skb(size, GFP_KERNEL);
- size = SKB_DATA_ALIGN(size) +
- SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
-
- data = vmalloc(size);
- if (data == NULL)
+ data = kvmalloc(head_size, GFP_KERNEL);
+ if (!data)
return NULL;
- skb = __build_skb(data, size);
- if (skb == NULL)
- vfree(data);
- else
+ skb = __build_skb(data, head_size);
+ if (!skb)
+ kvfree(data);
+ else if (is_vmalloc_addr(data))
skb->destructor = netlink_skb_destructor;
return skb;
