From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5FF17C04EB9 for ; Wed, 5 Dec 2018 13:41:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2DF952081B for ; Wed, 5 Dec 2018 13:41:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2DF952081B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-m68k.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mips-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727094AbeLENln (ORCPT ); Wed, 5 Dec 2018 08:41:43 -0500 Received: from mail-vk1-f193.google.com ([209.85.221.193]:35716 "EHLO mail-vk1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727025AbeLENln (ORCPT ); Wed, 5 Dec 2018 08:41:43 -0500 Received: by mail-vk1-f193.google.com with SMTP id b18so4656839vke.2; Wed, 05 Dec 2018 05:41:42 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=EGK1Cc1IT+4U8/m30kOf91EPSOF+4KfsAR6smtke9ew=; b=Kd0R6fOCTM6cwRcUqhSkmRNePRP5MVlvOFEM2CamleyTQI95BN23W87am33kk097CN vGfB25gSaQMvUF1it008P6Ien6zsztr6+w8TwvZvqcO1lRH5dsm0TgJQ12nzN5tc0HrA dAIl4RhgjeF74eP33jMIdMO3MIpKhrrs4J4yqjGUpzbz68bAAzwA3Z5kz0kA/5lB8BqU MBt3TgNJmBNhpYwHlKRuf+5vQ1jMuqoRl8LcUyx8fNINXDar/GLof8opildTuLvoQuPI tKnbVknG/3vgAHGE6pTY4Qzry3ooFSWRnjsp1M4Vbz/QNrPgQK2tkhbZdmELMAd9B6cn 9L3Q== X-Gm-Message-State: AA+aEWYJ4BcAJcSSi8UD26rj2MRZ2TFyIDuM+sp7obLVv8zElAr6aEfr U5flFI6soUP5wesxnTKEZfKqVm6Dr+D1FdMbptHn8g== X-Google-Smtp-Source: AFSGD/UZxgwhoo3/ppSmWmzsZH+UyBcxsNlADfgaaKBa1qo6XfRz9WxR6+aOWzoKr77RmzzncZKUDHu4KJGSKnRIxHI= X-Received: by 2002:a1f:91cb:: with SMTP id t194mr10817554vkd.74.1544017302275; Wed, 05 Dec 2018 05:41:42 -0800 (PST) MIME-Version: 1.0 References: <20181205.221146.969453990167463340.anemo@mba.ocn.ne.jp> In-Reply-To: <20181205.221146.969453990167463340.anemo@mba.ocn.ne.jp> From: Geert Uytterhoeven Date: Wed, 5 Dec 2018 14:41:30 +0100 Message-ID: Subject: Re: NFS/TCP crashes on MIPS/RBTX4927 in v4.20-rcX (bisected) To: Atsushi Nemoto Cc: Trond Myklebust , "open list:NFS, SUNRPC, AND..." , linux-mips@vger.kernel.org, Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Hi Nemoto-san, On Wed, Dec 5, 2018 at 2:11 PM Atsushi Nemoto wrote: > On Tue, 4 Dec 2018 14:53:07 +0100, Geert Uytterhoeven wrote: > > I found similar crashes in a report from 2006, but of course the code > > has changed too much to apply the solution proposed there > > (https://www.linux-mips.org/archives/linux-mips/2006-09/msg00169.html). > > > > Userland is Debian 8 (the last release supporting "old" MIPS). > > My kernel is based on v4.20.0-rc5, but the issue happens with v4.20-rc1, > > too. > > > > However, I noticed it works in v4.19! Hence I've bisected this, to commit > > 277e4ab7d530bf28 ("SUNRPC: Simplify TCP receive code by switching to using > > iterators"). > > > > Dropping the ",tcp" part from the nfsroot parameter also fixes the issue. > > > > Given RBTX4927 is little endian, just like my arm/arm64 boards, it's probably > > not an endianness issue. Sparse didn't show anything suspicious before/after > > the guilty commit. > > > > Do you have a clue? > > If it was a cache issue, disabling i-cache or d-cache completely might > help understanding the problem. I added TXx9 specific "icdisable" and > "dcdisable" kernel options for debugging long ago. > > I hope these options still works correctly with recent kernel but not > sure. > > Also, disabling i-cache makes your board VERY slow, of course. Thanks! When using these options, I do see a slowdown in early boot, but the issue is still there. My next guess is an unaligned access not using {get,put}_unaligned(), which doesn't seem to work on tx4927, but doesn't cause an exception neither. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds