From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH] igb: don't reuse pages with pfmemalloc flag Date: Wed, 22 Oct 2014 08:45:37 -0700 Message-ID: <1413992737.9031.1.camel@edumazet-glaptop2.roam.corp.google.com> References: <1413985819-9553-1-git-send-email-klamm@yandex-team.ru> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: alexander.h.duyck@intel.com, netdev@vger.kernel.org, sassmann@kpanic.de, e1000-devel@lists.sourceforge.net, peter.p.waskiewicz.jr@intel.com, bruce.w.allan@intel.com, jesse.brandeburg@intel.com, davem@davemloft.net, john.ronciak@intel.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org To: Roman Gushchin Return-path: In-Reply-To: <1413985819-9553-1-git-send-email-klamm@yandex-team.ru> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: e1000-devel-bounces@lists.sourceforge.net List-Id: netdev.vger.kernel.org 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 > --- 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