Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932434AbcCUVmQ (ORCPT ); Mon, 21 Mar 2016 17:42:16 -0400 Received: from mail-wm0-f42.google.com ([74.125.82.42]:35282 "EHLO mail-wm0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758072AbcCUVmO (ORCPT ); Mon, 21 Mar 2016 17:42:14 -0400 Date: Mon, 21 Mar 2016 21:42:09 +0000 From: Chris Bainbridge To: bp@alien8.de Cc: linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org, mchehab@infradead.org, markus@trippelsdorf.de, tony.luck@intel.com Subject: [BUG] packet loss with PROVE_LOCKING, bisected to EDAC fix Message-ID: <20160321214209.GA8480@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 731 Lines: 22 Hi, I was testing something on an old server (Dell T105 opteron) and noticed packet loss after updating the kernel from 3.10 to 4.5. The test was: On Dell run: iperf -s On another system: iperf3 -c dell -u -b 20M -l 1k -t 1000 This sends a 20mbit UDP stream to the Dell. It works fine normally (0% packet loss), but when CONFIG_PROVE_LOCKING is enabled there is high (35%) packet loss. (DEBUG_LOCKDEP also seems to cause packet loss) The packet loss bisected back to: commit 88d84ac97378c2f1d5fec9af1e8b7d9a662d6b00 Author: Borislav Petkov Date: Fri Jul 19 12:28:25 2013 +0200 EDAC: Fix lockdep splat I have confirmed that the commit preceding this (v3.11-rc1) is fine and that 88d84a introduced the bug.