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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Qian Cai <cai@lca.pw>
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Subject: Re: [patch V9 10/39] x86/entry: Provide helpers for execute on irqstack
In-Reply-To: <20200609023259.GA3579@lca.pw>
Date:   Tue, 09 Jun 2020 22:33:43 +0200
Message-ID: <87zh9cnfmg.fsf@nanos.tec.linutronix.de>
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Qian,

Qian Cai <cai@lca.pw> writes:
> On Tue, Jun 09, 2020 at 12:20:06AM +0200, Thomas Gleixner wrote:
>> Note, that I doubled the size of the stack depot so that we get real
>> numbers and not the cutoff by the size limit. IOW, the warning should
>> not trigger anymore. If it triggers nevertheless then the numbers will
>> still tell us an interesting story.
>
> Instead of running the whole testsuite, I just picked this single LTP
> oom02 test which seems usually trigger it within the testsuite. Let me
> know if this is insufficient (which indeed tell the big difference in
> "Unique stacks"), and I am happy to run the whole things.

thanks for providing the data.

> BAD: next-20200608
> GOOD: next-20200528 (which does not include this series)
>
> BAD (after boot)
> # cat /sys/kernel/debug/stackdepot/info
> Unique stacks: 33547
> Depot index:   359
> Depot offset:  6752
>
> BAD (after oom02)
> # cat /sys/kernel/debug/stackdepot/info
> Unique stacks: 140476

That's indeed odd. I try to reproduce and figure out what really breaks
here.

Thanks,

        tglx