Messages in this thread | | | Subject | Re: [PATCH v5 2/2] x86 mce: use new printk recursion disabling interface | From | Yanmin Zhang <> | Date | Wed, 06 Jun 2012 08:36:05 +0800 |
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On Tue, 2012-06-05 at 17:15 +0200, Borislav Petkov wrote: > On Tue, Jun 05, 2012 at 05:55:22PM +0800, ShuoX Liu wrote: > > From: ShuoX Liu <shuox.liu@intel.com> > > > > On x86 machines, some times MCE happens just when kernel calls printk > > to output some log info to serial console, while usually MCE module in > > kernel is used to print out some hardware error information, such like > > bad cache or bad memory bank. That causes printk recursion and printk > > would omit MCE printk output. > > > > We hit it when running MTBF testing on Android ATOM mobiles. > > > > Here in mce_panic, we choose to disable printk recursion to make sure > > MCE logs printed out. > > > > Signed-off-by: Yanmin Zhang <yanmin_zhang@linux.intel.com> > > Signed-off-by: ShuoX Liu <shuox.liu@intel.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..906e838 100644 > > --- a/arch/x86/kernel/cpu/mcheck/mce.c > > +++ b/arch/x86/kernel/cpu/mcheck/mce.c > > @@ -306,6 +306,7 @@ static void mce_panic(char *msg, struct mce *final, char *exp) > > { > > int i, apei_err = 0; > > > > + printk_recursion_check_disable(); > > if (!fake_panic) { > > /* > > * Make sure only one CPU runs in machine check panic > > @@ -360,6 +361,7 @@ static void mce_panic(char *msg, struct mce *final, char *exp) > > panic(msg); > > } else > > pr_emerg(HW_ERR "Fake kernel panic: %s\n", msg); > > + printk_recursion_check_enable(); > > Ok, let me ask this again: why not disable the printk recursion check in > the function that actually _prints_ the MCE, i.e. print_mce() instead of > here in mce_panic() which does a whole bunch of other stuff and it can > also return without printing any MCE to dmesg? Sorry for forgetting the return checking.
> Are you interested in seeing the printk's from mce_panic? Why? How about moving the disabling checking in print_mce? It seems not clean if we disable the printk recursion checking just around every printk statement.
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