| From foo@baz Wed Apr 29 11:59:49 CEST 2015 |
| From: Eric Dumazet <edumazet@google.com> |
| Date: Wed, 22 Apr 2015 07:33:36 -0700 |
| Subject: net: do not deplete pfmemalloc reserve |
| |
| From: Eric Dumazet <edumazet@google.com> |
| |
| [ Upstream commit 79930f5892e134c6da1254389577fffb8bd72c66 ] |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| net/core/skbuff.c | 9 +++++++-- |
| 1 file changed, 7 insertions(+), 2 deletions(-) |
| |
| --- a/net/core/skbuff.c |
| +++ b/net/core/skbuff.c |
| @@ -311,7 +311,11 @@ struct sk_buff *build_skb(void *data, un |
| |
| 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(s |
| 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); |
| } |
