linux-kernel - Re: [PATCH -next v2] riscv: add VMAP

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Message-ID: <52e3626a-2b40-bda6-de0e-68ea12a86dd9@huawei.com>
Date:   Fri, 23 Jul 2021 09:36:47 +0800
From:   tongtiangen <tongtiangen@...wei.com>
To:     Jisheng Zhang <jszhang3@...l.ustc.edu.cn>,
        Andreas Schwab <schwab@...ux-m68k.org>
CC:     Atish Patra <atishp@...shpatra.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next v2] riscv: add VMAP_STACK overflow detection



On 2021/7/23 7:54, Jisheng Zhang wrote:
> On Thu, 22 Jul 2021 17:42:52 +0200
> Andreas Schwab <schwab@...ux-m68k.org> wrote:
>
>> On Jul 22 2021, Jisheng Zhang wrote:
>>
>>> I think we need to pin the stack before calling get_wchan(), could you please
>>> try below patch?
>>
>> Thanks, this fixes the crash for me.
>>
>> Andreas.
>>
>
> Thanks for testing. I will send out formal patch later
>
> Thanks
>
> .
>

Hi all:
I tried to reproduced this crash in openSUSE code repo（ 
https://github.com/opensuse/kernel ）, but not reproduced successfully.

 From the patch of problem repair, the crash is due to task->stack is 
released before calling get_wchan, the task state of maybe TASK_DEAD.

VMAP_STACK is used to detect kernel stack overflow, there is no 
connection between the two, it makes me a little confused.