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net: do not deplete pfmemalloc reserve

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build_skb() should look at the page pfmemalloc status.
If set, this means page allocator allocated this page in the
expectation it would help to free other pages. Networking
stack can do that only if skb->pfmemalloc is also set.

Also, we must refrain using high order pages from the pfmemalloc
reserve, so __page_frag_refill() must also use __GFP_NOMEMALLOC for
them. Under memory pressure, using order-0 pages is probably the best
strategy.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2015-04-22 07:33:36 -07:00 committed by David S. Miller
parent 26349c71b4
commit 79930f5892
1 changed files with 7 additions and 2 deletions
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9
net/core/skbuff.c
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@ -311,7 +311,11 @@ struct sk_buff *build_skb(void *data, unsigned int frag_size)
memset(skb, 0, offsetof(struct sk_buff, tail));
skb->truesize = SKB_TRUESIZE(size);
skb->head_frag = frag_size != 0;
if (frag_size) {
skb->head_frag = 1;
if (virt_to_head_page(data)->pfmemalloc)
skb->pfmemalloc = 1;
}
atomic_set(&skb->users, 1);
skb->head = data;
skb->data = data;
@ -348,7 +352,8 @@ static struct page *__page_frag_refill(struct netdev_alloc_cache *nc,
gfp_t gfp = gfp_mask;
if (order) {
gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY;
gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY |
__GFP_NOMEMALLOC;
page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
nc->frag.size = PAGE_SIZE << (page ? order : 0);
}