linux-kernel - Re: [lkp-robot] [x86/mce] 5de97c9f6d: WARNING:at_arch/x86/kernel/cpu/mcheck/mce.c:#mce_register_decode

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Date:   Tue, 18 Apr 2017 09:38:20 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     kernel test robot <xiaolong.ye@...el.com>
Cc:     Tony Luck <tony.luck@...el.com>, Ingo Molnar <mingo@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-edac <linux-edac@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>, lkp@...org
Subject: Re: [lkp-robot] [x86/mce]  5de97c9f6d:
 WARNING:at_arch/x86/kernel/cpu/mcheck/mce.c:#mce_register_decode_chain

On Tue, Apr 18, 2017 at 10:24:45AM +0800, kernel test robot wrote:
> 
> FYI, we noticed the following commit:
> 
> commit: 5de97c9f6d85fd83af76e09e338b18e7adb1ae60 ("x86/mce: Factor out and deprecate the /dev/mcelog driver")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> 
> in testcase: boot
> 
> on test machine: qemu-system-i386 -enable-kvm -m 320M
> 
> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
> 
> 
> +------------------------------------------------------------------------+------------+------------+
> |                                                                        | 011d826111 | 5de97c9f6d |
> +------------------------------------------------------------------------+------------+------------+
> | boot_successes                                                         | 4          | 0          |
> | boot_failures                                                          | 50         | 12         |
> | WARNING:at_arch/x86/mm/dump_pagetables.c:#note_page                    | 50         | 6          |
> | WARNING:at_arch/x86/kernel/cpu/mcheck/mce.c:#mce_register_decode_chain | 0          | 12         |
> +------------------------------------------------------------------------+------------+------------+
> 
> 
> 
> [   39.479771] WARNING: CPU: 0 PID: 1 at arch/x86/kernel/cpu/mcheck/mce.c:162 mce_register_decode_chain+0x26/0x35
> [   39.479771] WARNING: CPU: 0 PID: 1 at arch/x86/kernel/cpu/mcheck/mce.c:162 mce_register_decode_chain+0x26/0x35

Ah, that's the prio check. Thanks for reporting, here's a correction:

---
From: Borislav Petkov <bp@...e.de>
Date: Tue, 18 Apr 2017 09:33:28 +0200
Subject: [PATCH] x86/mce: Update notifier priority check

Update the check which enforces the registration of MCE decoder notifier
callbacks with valid priority only, to include mcelog's priority.

Reported-by: kernel test robot <xiaolong.ye@...el.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Link: http://lkml.kernel.org/r/20170418022445.GE1143@yexl-desktop
---
 arch/x86/kernel/cpu/mcheck/mce.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index a09bb6775c23..9d41ec8c8927 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -157,7 +157,7 @@ static atomic_t num_notifiers;
 
 void mce_register_decode_chain(struct notifier_block *nb)
 {
-	if (WARN_ON(nb->priority > MCE_PRIO_LOWEST && nb->priority < MCE_PRIO_EDAC))
+	if (WARN_ON(nb->priority > MCE_PRIO_MCELOG && nb->priority < MCE_PRIO_EDAC))
 		return;
 
 	atomic_inc(&num_notifiers);
-- 
2.11.0

-- 
Regards/Gruss,
    Boris.

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