linux-kernel - Re: [PATCH v3 2/2] x86 mce: use new printk recursion disabling interface

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Date:	Tue, 05 Jun 2012 08:32:40 +0800
From:	Yanmin Zhang <yanmin_zhang@...ux.intel.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	ShuoX Liu <shuox.liu@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Luck, Tony" <tony.luck@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"andi@...stfloor.org" <andi@...stfloor.org>,
	Ingo Molnar <mingo@...e.hu>,
	"andi@...stfloor.org" <andi@...stfloor.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH v3 2/2] x86 mce: use new printk recursion disabling
 interface

On Mon, 2012-06-04 at 19:12 +0200, Borislav Petkov wrote:
> On Mon, May 28, 2012 at 10:56:04AM +0800, ShuoX Liu wrote:
> > From: ShuoX Liu <shuox.liu@...el.com>
> > 
> > Disable printk recursion to make sure MCE logs printed out.
> > 
> > Signed-off-by: Yanmin Zhang <yanmin_zhang@...ux.intel.com>
> > Signed-off-by: ShuoX Liu <shuox.liu@...el.com>
> > ---
> >  arch/x86/kernel/cpu/mcheck/mce.c |    2 ++
> >  1 files changed, 2 insertions(+), 0 deletions(-)
> > 
> > diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
> > index 2afcbd2..365c35d 100644
> > --- a/arch/x86/kernel/cpu/mcheck/mce.c
> > +++ b/arch/x86/kernel/cpu/mcheck/mce.c
> > @@ -1015,6 +1015,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
> >  	DECLARE_BITMAP(toclear, MAX_NR_BANKS);
> >  	char *msg = "Unknown";
> >  
> > +	printk_recursion_check_disable();
> >  	atomic_inc(&mce_entry);
> >  
> >  	this_cpu_inc(mce_exception_count);
> > @@ -1144,6 +1145,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
> >  	mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
> >  out:
> >  	atomic_dec(&mce_entry);
> > +	printk_recursion_check_enable();
> >  	sync_core();
> 
> This is still adding the recursion check things in do_machine_check
> instead of in print_mce.
Boris,

You are seeing an old patch. The new patches V4 are:
https://lkml.org/lkml/2012/6/3/176
https://lkml.org/lkml/2012/6/3/177


The new patches change mce_panic instead of do_machine_check.

> 
> Also, this commit message above needs more explanation why we want to
> disable the recursion check on an MCE, maybe an example...
V4 doesn't have the comment. We would add it in V5.

Thanks.


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