On Wed, 2014-10-22 at 17:50 +0400, Roman Gushchin wrote: > 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 <kl...@yandex-team.ru> > ---
Interesting... It seems we also need to clear skb->pfmemalloc in napi_reuse_skb() ------------------------------------------------------------------------------ _______________________________________________ E1000-devel mailing list E1000-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/e1000-devel To learn more about Intel® Ethernet, visit http://communities.intel.com/community/wired
