"random" segment faults in expect running GCC regression test on LoongArch

[Xi Ruoyao]

On Wed, 2022-11-09 at 15:43 +0800, Xi Ruoyao wrote:
> Hi,
> 
> This is a "help wanted" message.  When I run GCC regression test on
> loongarch64-linux-gnu, expect occasionally crashes with a segment fault.
> The stack backtrace is like:

/* snip */

> The crashes happen on both my own LoongArch board and
> gcc401.fsffrance.org.  So I don't think it was an "only me" problem.
> 
> The segment fault is not deterministic.  A Expect command like
> 
> cd /path/to/gcc/build/gcc
> expect -- /usr/share/dejagnu/runtest.exp --tool gfortran dg.exp=bind-c-contiguous-1.f90
> 
> sometimes succeeds, sometimes immediately segfaults, sometimes prints
> several lines of strange error message and then exits abnormally.
> 
> Usually I don't like to send "help wanted" messages, but this time I
> have no idea how to fix (or even triage) the problem.  I don't even know
> which component (Tcl? Expect? GCC? Glibc? Kernel?) I should blame.  So
> it seems I really need some help now...

I'm now 99% sure this is a kernel issue:

https://lore.kernel.org/loongarch/20221117042532.4064448-1-chenhuacai@loongson.cn/

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University