linux-kernel - Re: [PATCH 0/4] Fix a segmentation fault also add raid6test for RISC-V support

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Message-ID: <mhng-D97D0B5D-7948-49C6-8F55-C0836E41DA3C@palmerdabbelt-mac>
Date: Tue, 10 Jun 2025 15:00:24 -0700 (PDT)
From: Palmer Dabbelt <palmer@...belt.com>
To: Alexandre Ghiti <alex@...ti.fr>
CC: zhangchunyan@...as.ac.cn, Paul Walmsley <paul.walmsley@...ive.com>,
  aou@...s.berkeley.edu, Charlie Jenkins <charlie@...osinc.com>, song@...nel.org, yukuai3@...wei.com,
  linux-riscv@...ts.infradead.org, linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org, zhang.lyra@...il.com
Subject:     Re: [PATCH 0/4] Fix a segmentation fault also add raid6test for RISC-V support

On Tue, 10 Jun 2025 12:23:18 PDT (-0700), Alexandre Ghiti wrote:
> Hi Chunyan,
>
> On 6/10/25 12:12, Chunyan Zhang wrote:
>> The first two patches are fixes.
>> The last two are for userspace raid6test support on RISC-V.
>>
>> The issue fixed in patch 2/4 was probably the same which was spotted by
>> Charlie [1], I couldn't reproduce it at that time.
>>
>> When running raid6test in userspace on RISC-V, I saw a segmentation fault,
>> I used gdb command to print pointer p, it was an unaccessible address.
>
>
> Can you give me your config, kernel and toolchain versions? I can't
> reproduce the segfault on my machine.

It's probably going to be super fragile to reproduce.  The code is just 
scrubbing over t0 without a clobber, so it's just going to break stuff 
somewhat arbitrarily.

>
> Thanks for the fixes and the test, I'll take a look this week.
>
> Alex
>
>
>>
>> With patch 2/4, the issue didn't appear anymore.
>>
>> [1] https://lore.kernel.org/lkml/Z5gJ35pXI2W41QDk@ghost/
>>
>> Chunyan Zhang (4):
>>    raid6: riscv: clean up unused header file inclusion
>>    raid6: riscv: Fix NULL pointer dereference issue
>>    raid6: riscv: Allow code to be compiled in userspace
>>    raid6: test: add support for RISC-V
>>
>>   lib/raid6/recov_rvv.c   |  9 +-----
>>   lib/raid6/rvv.c         | 62 +++++++++++++++++++++--------------------
>>   lib/raid6/rvv.h         | 15 ++++++++++
>>   lib/raid6/test/Makefile |  8 ++++++
>>   4 files changed, 56 insertions(+), 38 deletions(-)
>>