Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756018AbaBEU5L (ORCPT ); Wed, 5 Feb 2014 15:57:11 -0500 Received: from mail.windriver.com ([147.11.1.11]:54744 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754535AbaBEUFc (ORCPT ); Wed, 5 Feb 2014 15:05:32 -0500 From: Paul Gortmaker To: , CC: Willy Tarreau , Paul Gortmaker Subject: [v2.6.34-stable 063/213] tcp: do_tcp_sendpages() must try to push data out on oom conditions Date: Wed, 5 Feb 2014 15:00:18 -0500 Message-ID: <1391630568-49251-64-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.8.5.2 In-Reply-To: <1391630568-49251-1-git-send-email-paul.gortmaker@windriver.com> References: <1391630568-49251-1-git-send-email-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Willy Tarreau ------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. ------------------- commit bad115cfe5b509043b684d3a007ab54b80090aa1 upstream. Since recent changes on TCP splicing (starting with commits 2f533844 "tcp: allow splice() to build full TSO packets" and 35f9c09f "tcp: tcp_sendpages() should call tcp_push() once"), I started seeing massive stalls when forwarding traffic between two sockets using splice() when pipe buffers were larger than socket buffers. Latest changes (net: netdev_alloc_skb() use build_skb()) made the problem even more apparent. The reason seems to be that if do_tcp_sendpages() fails on out of memory condition without being able to send at least one byte, tcp_push() is not called and the buffers cannot be flushed. After applying the attached patch, I cannot reproduce the stalls at all and the data rate it perfectly stable and steady under any condition which previously caused the problem to be permanent. The issue seems to have been there since before the kernel migrated to git, which makes me think that the stalls I occasionally experienced with tux during stress-tests years ago were probably related to the same issue. This issue was first encountered on 3.0.31 and 3.2.17, so please backport to -stable. Signed-off-by: Willy Tarreau Acked-by: Eric Dumazet Signed-off-by: Paul Gortmaker --- net/ipv4/tcp.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index df671c76f196..392d594521c1 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -839,8 +839,7 @@ new_segment: wait_for_sndbuf: set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); wait_for_memory: - if (copied) - tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH); + tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH); if ((err = sk_stream_wait_memory(sk, &timeo)) != 0) goto do_error; -- 1.8.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/