Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751781AbbLUUeV (ORCPT ); Mon, 21 Dec 2015 15:34:21 -0500 Received: from vulcan.natalenko.name ([104.207.131.136]:51620 "EHLO vulcan.natalenko.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751204AbbLUUeU convert rfc822-to-8bit (ORCPT ); Mon, 21 Dec 2015 15:34:20 -0500 X-Greylist: delayed 526 seconds by postgrey-1.27 at vger.kernel.org; Mon, 21 Dec 2015 15:34:19 EST DMARC-Filter: OpenDMARC Filter v1.3.1 vulcan.natalenko.name D87226F368 Authentication-Results: vulcan.natalenko.name; dmarc=none header.from=natalenko.name From: Oleksandr Natalenko To: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Patrick McHardy , Hideaki YOSHIFUJI , James Morris , Alexey Kuznetsov , "David S. Miller" , Yuchung Cheng Subject: [REGRESSION] tcp/ipv4: kernel panic because of (possible) division by zero Date: Mon, 21 Dec 2015 22:25:30 +0200 Message-ID: <26396443.iDTTxgChSj@spock> User-Agent: KMail/5.1 (Linux/4.3.0-pf3; KDE/5.17.0; x86_64; ; ) MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 853 Lines: 22 Commit 3759824da87b30ce7a35b4873b62b0ba38905ef5 (tcp: PRR uses CRB mode by default and SS mode conditionally) introduced changes to net/ipv4/tcp_input.c tcp_cwnd_reduction() that, possibly, cause division by zero, and therefore, kernel panic in interrupt handler [1]. Reverting 3759824da87b30ce7a35b4873b62b0ba38905ef5 seems to fix the issue. I'm able to reproduce the issue on 4.3.0–4.3.3 once per several day (occasionally). What could be done to help in debugging this issue? Regards, Oleksandr. [1] http://i.piccy.info/ i9/6f5cb187c4ff282d189f78c63f95af43/1450729403/283985/951663/panic.jpg -- 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/