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Subject: Re: [PATCH V5 00/22] arch: Add basic LoongArch support
From:   Xi Ruoyao <xry111@mengyan1223.wang>
To:     Huacai Chen <chenhuacai@gmail.com>
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>,
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        "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>
Date:   Thu, 06 Jan 2022 01:21:46 +0800
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On Wed, 2022-01-05 at 19:51 +0800, Xi Ruoyao wrote:
> On Wed, 2022-01-05 at 17:40 +0800, Huacai Chen wrote:
> > 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.
> 
> Is there any workload which can triggers the panic?  I can't trigger it
> by building and testing GCC, or building the kernel anymore.
> 
> And is your "stable" issue the same one I'd encountered?  To me changing
> barrier() to smp_mb() may fix some deadlock, but not a panic.  (I'm not
> an expert on CPU architecture or kernel programming, so maybe I'm wrong
> here.)
> 
> I'll put my 3A5000 machine into a loop building kernel and see if I can
> trigger the panic again...

I can't reproduce the issue on 5.16-rc8.  But I can reproduce it on
5.16-rc5 and the s/barrier/smp_mb/ change fixes the issue.

I'm still puzzled: if there some workload which can reproduce the issue
more deterministic?
-- 
Xi Ruoyao <xry111@mengyan1223.wang>
School of Aerospace Science and Technology, Xidian University