From bc16e47f03a7dce9ad68029b21519265c334eb12 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Thu, 23 Oct 2014 03:32:27 +0000 Subject: [PATCH] igb: don't reuse pages with pfmemalloc flag Incoming packet is dropped silently by sk_filter(), if the skb was allocated from pfmemalloc reserves and the corresponding socket is not marked with the SOCK_MEMALLOC flag. Igb driver allocates pages for DMA with __skb_alloc_page(), which calls alloc_pages_node() with the __GFP_MEMALLOC flag. So, in case of OOM condition, igb can get pages with pfmemalloc flag set. If an incoming packet hits the pfmemalloc page and is large enough (small packets are copying into the memory, allocated with netdev_alloc_skb_ip_align(), so they are not affected), it will be dropped. This behavior is ok under high memory pressure, but the problem is that the igb driver reuses these mapped pages. So, packets are still dropping even if all memory issues are gone and there is a plenty of free memory. In my case, some TCP sessions hang on a small percentage (< 0.1%) of machines days after OOMs. Fix this by avoiding reuse of such pages. Signed-off-by: Roman Gushchin Tested-by: Aaron Brown "aaron.f.brown@intel.com" Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/igb/igb_main.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c index a21b144..a2d72a8 100644 --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -6537,6 +6537,9 @@ static bool igb_can_reuse_rx_page(struct igb_rx_buffer *rx_buffer, if (unlikely(page_to_nid(page) != numa_node_id())) return false; + if (unlikely(page->pfmemalloc)) + return false; + #if (PAGE_SIZE < 8192) /* if we are only owner of page we can reuse it */ if (unlikely(page_count(page) != 1)) @@ -6603,7 +6606,8 @@ static bool igb_add_rx_frag(struct igb_ring *rx_ring, memcpy(__skb_put(skb, size), va, ALIGN(size, sizeof(long))); /* we can reuse buffer as-is, just make sure it is local */ - if (likely(page_to_nid(page) == numa_node_id())) + if (likely((page_to_nid(page) == numa_node_id()) && + !page->pfmemalloc)) return true; /* this page cannot be reused so discard it */ -- 2.7.4