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

[Palmer Dabbelt]

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(-)