tests: Flaky strace-tst-thp-*-disabled tests

[Yury Khrustalev]

On Wed, Aug 19, 2026 at 10:54:19AM -0300, Adhemerval Zanella Netto wrote:
> 
> On 19/08/26 08:48, Yury Khrustalev wrote:
> > On Wed, Aug 19, 2026 at 08:34:30AM -0300, Adhemerval Zanella Netto wrote:
> >>
> >> On 19/08/26 05:55, Yury Khrustalev wrote:
> >>> Hi everyone,
> >>>
> >>> Has anyone else noticed that the elf/strace-tst-thp-*-disabled tests are
> >>> flaky producing FAIL results because madvise syscall occasionally occurs
> >>> despite using tunable glibc.elf.thp=0?
> >>>
> >>> The current logic of how this tunable is handled is a bit complex, I'm
> >>> trying to pin point the reason for this, but I've seen these tests
> >>> failing from time to time with no particular pattern.
> >> I recalled that I saw some spurious issue after the release, but I haven't
> >> see any after 2be733e9e0b2e8871cd282f2ee868d75108db7f1. I will double check.
> > 
> > I see it on recent master including today's commit a0faa928b0.
> > 
> >   fails=0; for ((i=0;i<100;i++)); \
> >     do make test t=elf/strace-tst-thp-1-disabled |& grep -qw FAIL && ((fails++)); \
> >     done; echo "$fails failed"
> > 
> > I see ~7 failures for 100 test runs.
> 
> Ack, I could reproduce it and the strace output for the failures is:
> 
> --
>
> ...
>
> I think the cleanest fix would be to add glibc.malloc.hugetlb=0 in all the
> strace-tst-thp-* Makefile rules.

I've sent a patch:
https://inbox.sourceware.org/libc-alpha/20260824151034.1838519-1-yury.khrustalev@arm.com/

Thanks,
Yury