From 0614002bb5f7411e61ffa0dfe5be1f2c84df3da3 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Tue, 31 Jul 2012 16:44:24 -0700 Subject: netvm: propagate page->pfmemalloc from skb_alloc_page to skb The skb->pfmemalloc flag gets set to true iff during the slab allocation of data in __alloc_skb that the the PFMEMALLOC reserves were used. If page splitting is used, it is possible that pages will be allocated from the PFMEMALLOC reserve without propagating this information to the skb. This patch propagates page->pfmemalloc from pages allocated for fragments to the skb. It works by reintroducing and expanding the skb_alloc_page() API to take an skb. If the page was allocated from pfmemalloc reserves, it is automatically copied. If the driver allocates the page before the skb, it should call skb_propagate_pfmemalloc() after the skb is allocated to ensure the flag is copied properly. Failure to do so is not critical. The resulting driver may perform slower if it is used for swap-over-NBD or swap-over-NFS but it should not result in failure. [davem@davemloft.net: API rename and consistency] Signed-off-by: Mel Gorman Acked-by: David S. Miller Cc: Neil Brown Cc: Peter Zijlstra Cc: Mike Christie Cc: Eric B Munson Cc: Eric Dumazet Cc: Sebastian Andrzej Siewior Cc: Mel Gorman Cc: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/skbuff.h | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) (limited to 'include') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index b814bb8fd5a..7632c87da2c 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1774,6 +1774,61 @@ static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev, return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC); } +/* + * __skb_alloc_page - allocate pages for ps-rx on a skb and preserve pfmemalloc data + * @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX + * @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used + * @order: size of the allocation + * + * Allocate a new page. + * + * %NULL is returned if there is no free memory. +*/ +static inline struct page *__skb_alloc_pages(gfp_t gfp_mask, + struct sk_buff *skb, + unsigned int order) +{ + struct page *page; + + gfp_mask |= __GFP_COLD; + + if (!(gfp_mask & __GFP_NOMEMALLOC)) + gfp_mask |= __GFP_MEMALLOC; + + page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, order); + if (skb && page && page->pfmemalloc) + skb->pfmemalloc = true; + + return page; +} + +/** + * __skb_alloc_page - allocate a page for ps-rx for a given skb and preserve pfmemalloc data + * @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX + * @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used + * + * Allocate a new page. + * + * %NULL is returned if there is no free memory. + */ +static inline struct page *__skb_alloc_page(gfp_t gfp_mask, + struct sk_buff *skb) +{ + return __skb_alloc_pages(gfp_mask, skb, 0); +} + +/** + * skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page + * @page: The page that was allocated from skb_alloc_page + * @skb: The skb that may need pfmemalloc set + */ +static inline void skb_propagate_pfmemalloc(struct page *page, + struct sk_buff *skb) +{ + if (page && page->pfmemalloc) + skb->pfmemalloc = true; +} + /** * skb_frag_page - retrieve the page refered to by a paged fragment * @frag: the paged fragment -- cgit v1.2.3-70-g09d2