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From:   Huacai Chen <chenhuacai@gmail.com>
Date:   Wed, 5 Jan 2022 17:40:49 +0800
Message-ID: <CAAhV-H6R=xWL18AH7HzeXHOVD_d-5m7RvdQCLkOR1NeDZ_0HMw@mail.gmail.com>
Subject: Re: [PATCH V5 00/22] arch: Add basic LoongArch support
To:     Xi Ruoyao <xry111@mengyan1223.wang>
Cc:     Huacai Chen <chenhuacai@loongson.cn>,
        Arnd Bergmann <arnd@arndb.de>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Airlie <airlied@linux.ie>,
        Jonathan Corbet <corbet@lwn.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Yanteng Si <siyanteng@loongson.cn>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>
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Hi, Ruoyao,

The problem still exists in 5.16-rc8, can you try to change
cpu_relax() definition to smp_mb()? It seems can fix the problem.

Huacai

On Tue, Dec 28, 2021 at 4:34 PM Xi Ruoyao <xry111@mengyan1223.wang> wrote:
>
> On Tue, 2021-12-21 at 15:53 +0800, Huacai Chen wrote:
>
> > On Mon, Dec 20, 2021 at 5:04 PM Xi Ruoyao <xry111@mengyan1223.wang>
> > wrote:
> > >
> > > The snapshot panics on my system under high pressure (building and
> > > testing GCC).  The panic message is pasted, but it's kind of broken up
> > > likely because multiple CPU cores were outputing to the serial console
> > > simutaniously.
> > >
> > > The config is attached.  I'm not sure the reason of the panic (bug in
> > > the patches or bug in mainline kernel?) Do you have some pointers to
> > > diagnostic and fix the issue?
> > >
> > > [ 5391.004745] CPU 1 Unable to handle kernel paging request at virtual address 000000000040007e, era == 90000000003aa07c, ra == 90000000003aa84c
>
> /* snip */
>
> > We also found that the latest github kernel has some stable issues,
> > and we are investigating.
>
> I rebased the patches onto 438645193e59e91761ccb3fa55f6ce70b615ff93 and
> the problem *seems* gone.  Not sure if it's something fixed in the
> mainline or some more strange thing.
> --
> Xi Ruoyao <xry111@mengyan1223.wang>
> School of Aerospace Science and Technology, Xidian University