linux-kernel - Re: [rfc/patch] mm/slub: restore/expand unfreeze

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Date:   Tue, 20 Jul 2021 13:26:14 +0200
From:   Mike Galbraith <efault@....de>
To:     Vlastimil Babka <vbabka@...e.cz>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     linux-rt-users@...r.kernel.org,
        Mel Gorman <mgorman@...hsingularity.net>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: Re: [rfc/patch] mm/slub: restore/expand unfreeze_partials() local
 exclusion scope

On Tue, 2021-07-20 at 10:56 +0200, Vlastimil Babka wrote:
>
> > crash> bt -sx
> > PID: 18761  TASK: ffff88812fff0000  CPU: 0   COMMAND: "hackbench"
> >  #0 [ffff88818f8ff980] machine_kexec+0x14f at ffffffff81051c8f
> >  #1 [ffff88818f8ff9c8] __crash_kexec+0xd2 at ffffffff8111ef72
> >  #2 [ffff88818f8ffa88] crash_kexec+0x30 at ffffffff8111fd10
> >  #3 [ffff88818f8ffa98] oops_end+0xd3 at ffffffff810267e3
> >  #4 [ffff88818f8ffab8] exc_general_protection+0x195 at ffffffff8179fdb5
> >  #5 [ffff88818f8ffb50] asm_exc_general_protection+0x1e at ffffffff81800a0e
> >     [exception RIP: __unfreeze_partials+156]
>
> Hm going back to this report...

> So could it be that it was stillput_cpu_partial() preempting
> __slab_alloc() messing the partial list, but for some reason the
> put_cpu_partial() side crashed this time?

Thinking this bug is toast, I emptied the trash bin, so no can peek.

If need be, and nobody beats me to it (which ~guarantees nobody will
beat me to it;), I can make the thing go boom again easily enough.

	-Mike