net: do not deplete pfmemalloc reserve (79930f58) · Commits · 戴 / test

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>

net/core/skbuff.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -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);
		}

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