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[209.132.180.67]) by mx.google.com with ESMTP id p16si19992836plr.31.2018.12.05.06.50.27; Wed, 05 Dec 2018 06:50:43 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727895AbeLEOr7 (ORCPT + 99 others); Wed, 5 Dec 2018 09:47:59 -0500 Received: from mail-vs1-f66.google.com ([209.85.217.66]:35538 "EHLO mail-vs1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727094AbeLEOr7 (ORCPT ); Wed, 5 Dec 2018 09:47:59 -0500 Received: by mail-vs1-f66.google.com with SMTP id e7so12227676vsc.2; Wed, 05 Dec 2018 06:47:58 -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=N4N2sZNH53i6D9yRmiCx9A+jnggLmHj8GKEOX/5FTrU=; b=syT0Cxd7iRsE6xxv81HldcaU5rcJwGRyThmoW1uaFEwCCS5GLOo0sUht3GViYaOlDQ ZG08GL4dKfbT30ZvwrHoetmxEi9f2MH672VbjGUQocW7rRNZH2TV4144pOKXUoeVQIfT votsd3vgZhMxnRJgR7G6m4YjD+Avxy+BDIxhL31mIR3wzRjAxiTV+tPVKQb+cpM8fRTB 6p6hxgF/+/uVfqhoaR2v22nheRIvW8yw6Ot1laZS/9uPA0ZYGo0Adr8Hr+ayMEiYuvrc qtpdf+dCutSdTbeW9Y4oXisYfPaNn9xrldXr8WtWuJyDWt7ZIQ6fGGeqG0XJ9tLA66LF AyqQ== X-Gm-Message-State: AA+aEWbyR8JtTLk47J4TusiJRd0cD3UnVJ+cGxCnD/huqxQKsseZXzq6 /emScrQSSuyfLcHDRuHBuZN/hBwi/4Ewy1RiGTz9Kw== X-Received: by 2002:a67:f43:: with SMTP id 64mr10935737vsp.166.1544021277718; Wed, 05 Dec 2018 06:47:57 -0800 (PST) MIME-Version: 1.0 References: <20181205.221146.969453990167463340.anemo@mba.ocn.ne.jp> <92ce4b8c2b2d53e27ed5bc0e5af3fee4bc17b4dc.camel@hammerspace.com> In-Reply-To: <92ce4b8c2b2d53e27ed5bc0e5af3fee4bc17b4dc.camel@hammerspace.com> From: Geert Uytterhoeven Date: Wed, 5 Dec 2018 15:47:45 +0100 Message-ID: Subject: Re: NFS/TCP crashes on MIPS/RBTX4927 in v4.20-rcX (bisected) To: trondmy@hammerspace.com Cc: Atsushi Nemoto , Linux Kernel Mailing List , "open list:NFS, SUNRPC, AND..." , linux-mips@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Trond, On Wed, Dec 5, 2018 at 2:45 PM Trond Myklebust wrote: > On Wed, 2018-12-05 at 14:41 +0100, Geert Uytterhoeven wrote: > > On Wed, Dec 5, 2018 at 2:11 PM Atsushi Nemoto > > wrote: > > > On Tue, 4 Dec 2018 14:53:07 +0100, Geert Uytterhoeven < > > > geert@linux-m68k.org> 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. > > Can you try my linux-next branch on git.linux-nfs.org? It contains a > fixes for a hang that results from the above commit. > > git pull git://git.linux-nfs.org/projects/trondmy/linux-nfs.git linux-next Thanks for the suggestion, but unfortunately it doesn't help. 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