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Subject: Re: Crash in fair scheduler
To:     Valentin Schneider <valentin.schneider@arm.com>,
        "Schmid, Carsten" <Carsten_Schmid@mentor.com>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "peterz@infradead.org" <peterz@infradead.org>,
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References: <1575364273836.74450@mentor.com>
 <564e45cb-8230-9c3d-24a8-b58e6e88349f@arm.com>
From:   Dietmar Eggemann <dietmar.eggemann@arm.com>
Message-ID: <944927a7-b578-c6f9-a73d-25c5b0a39adb@arm.com>
Date:   Tue, 3 Dec 2019 11:40:20 +0100
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On 03/12/2019 11:30, Valentin Schneider wrote:
> On 03/12/2019 09:11, Schmid, Carsten wrote:

[...]

> That looks a lot like a recent issue we've had, see
> 
>   https://lore.kernel.org/lkml/20191108131909.428842459@infradead.org/
> 
> The issue is caused by
>   
>   67692435c411 ("sched: Rework pick_next_task() slow-path")
> 
> which 5.4-rc2 has (without the fix which landed in -rc7) but 4.14 really
> shouldn't, unless the kernel you're using has had core scheduling somehow
> backported to it?
> 
> I've only scraped the surface but I'd like to first ask: can you reproduce
> the issue on v5.4 final ?

Can't be. 4.14.86 does not have ("sched: Rework pick_next_task()
slow-path").