linux-kernel - Re: [PATCH] x86/MCE/AMD: fix warning about sleep-in-atomic at early boot

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Message-ID: <20191217075355.GA15129@zn.tnic>
Date:   Tue, 17 Dec 2019 08:53:55 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc:     Yazen Ghannam <Yazen.Ghannam@....com>,
        Tony Luck <tony.luck@...el.com>, linux-kernel@...r.kernel.org,
        linux-edac@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH] x86/MCE/AMD: fix warning about sleep-in-atomic at early
 boot

On Thu, Nov 07, 2019 at 11:53:10AM +0100, Borislav Petkov wrote:
> On Fri, Nov 01, 2019 at 04:39:17PM +0300, Konstantin Khlebnikov wrote:
> > I tried 5.4 once but there was no warning.
> > Code in 4.19 and in mainline almost the same.
> 
> Yes, but early boot code has changed a lot since 4.19. If you can't
> trigger it on 5.4, then I'll drop the BUG splat from your commit message
> and change it to talk about replacing the IPI-sending function, which is
> a good cleanup in itself.

Ok, I was able to trigger it myself:

[    0.822602] BUG: sleeping function called from invalid context at kernel/sched/completion.c:99
[    0.822602] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1
[    0.822602] no locks held by swapper/1/0.
[    0.822602] irq event stamp: 0
[    0.822602] hardirqs last  enabled at (0): [<0000000000000000>] 0x0
[    0.822602] hardirqs last disabled at (0): [<ffffffff8106dda9>] copy_process+0x8b9/0x1ca0
[    0.822602] softirqs last  enabled at (0): [<ffffffff8106dda9>] copy_process+0x8b9/0x1ca0
[    0.822602] softirqs last disabled at (0): [<0000000000000000>] 0x0
[    0.822602] Preemption disabled at:
[    0.822602] [<ffffffff8104703b>] start_secondary+0x3b/0x190
[    0.822602] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.5.0-rc2+ #1
[    0.822602] Hardware name: GIGABYTE MZ01-CE1-00/MZ01-CE1-00, BIOS F02 08/29/2018
[    0.822602] Call Trace:
[    0.822602]  dump_stack+0x71/0xa0
[    0.822602]  ___might_sleep.cold.92+0xf7/0x11f
[    0.822602]  wait_for_completion+0x3c/0x180
[    0.822602]  ? generic_exec_single+0xca/0x100
[    0.822602]  rdmsr_safe_on_cpu+0xe8/0x100
[    0.822602]  ? wrmsr_on_cpus+0x20/0x20
[    0.822602]  mce_amd_feature_init+0x2ab/0x590
[    0.822602]  mcheck_cpu_init+0x17a/0x4d0
[    0.822602]  identify_cpu+0x3f0/0x750
[    0.822602]  identify_secondary_cpu+0x13/0x80
[    0.822602]  smp_store_cpu_info+0x45/0x50
[    0.822602]  start_secondary+0x50/0x190
[    0.822602]  secondary_startup_64+0xa4/0xb0

Rerouting patch...

Thx.

-- 
Regards/Gruss,
    Boris.

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