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Date: Tue, 30 Jan 2024 11:12:01 +0100
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Subject: Re: Several tst-robust* tests time out with recent Linux kernel
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To: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
        "peterz@infradead.org" <peterz@infradead.org>
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From: Stefan Liebler <stli@linux.ibm.com>
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On 29.01.24 23:23, Edgecombe, Rick P wrote:
> On Fri, 2024-01-19 at 14:56 +0100, Stefan Liebler wrote:
>> I've reduced the test (see attachement) and now have only one process
>> with three threads.
> 
> This tests fails on my setup as well:
> main: start 3 threads.
> #0: started: fct=1
> #1: started: fct=1
> #2: started: fct=1
> #2: mutex_timedlock failed with 22 (round=28772)
> 
> But, after this patch:
> https://lore.kernel.org/all/20240116130810.ji1YCxpg@linutronix.de/
> 
> ...the attached test hangs.
> 
> However, the glibc test that was failing for me "nptl/tst-robustpi8"
> passes with the linked patch applied. So I think that patch fixes the
> issue I hit.
> 
> What is passing supposed to look like on the attached test?

kernel commit "futex: Prevent the reuse of stale pi_state"
https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/patch/?id=e626cb02ee8399fd42c415e542d031d185783903

fixes the issue on s390x.

With this commit, the test runs to the end:
main: start 3 threads.
#0: started: fct=1
#1: started: fct=1
#2: started: fct=1
#2: REACHED round 100000000. => exit
#0: REACHED round 100000000. => exit
#1: REACHED round 100000000. => exit
main: end.

If you want you can reduce the number of rounds by compiling with
-DROUNDS=XYZ or manually adjusting the ROUNDS macro define.