Messages in this thread | | | Date | Tue, 5 Jun 2012 17:15:42 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v5 2/2] x86 mce: use new printk recursion disabling interface |
| |
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?
Are you interested in seeing the printk's from mce_panic? Why?
Thanks.
-- Regards/Gruss, Boris.
| |