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netlink: use kvmalloc() in netlink_alloc_large_skb()

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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>
This commit is contained in:
Eric Dumazet 2024-02-24 09:06:30 +00:00 committed by Jakub Kicinski
parent c4b04a802d
commit f8cbf6bde4
1 changed files with 8 additions and 10 deletions
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18
net/netlink/af_netlink.c
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@ -1202,23 +1202,21 @@ struct sock *netlink_getsockbyfilp(struct file *filp)
struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast) struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast)
{ {
size_t head_size = SKB_HEAD_ALIGN(size);
struct sk_buff *skb; struct sk_buff *skb;
void *data; void *data;
if (size <= NLMSG_GOODSIZE || broadcast) if (head_size <= PAGE_SIZE || broadcast)
return alloc_skb(size, GFP_KERNEL); return alloc_skb(size, GFP_KERNEL);
size = SKB_DATA_ALIGN(size) + data = kvmalloc(head_size, GFP_KERNEL);
SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); if (!data)
data = vmalloc(size);
if (data == NULL)
return NULL; return NULL;
skb = __build_skb(data, size); skb = __build_skb(data, head_size);
if (skb == NULL) if (!skb)
vfree(data); kvfree(data);
else else if (is_vmalloc_addr(data))
skb->destructor = netlink_skb_destructor; skb->destructor = netlink_skb_destructor;
return skb; return skb;