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SubjectRe: [PATCH -v3] x86, MCE: Drop the default decoding notifier

On 04/14/2011 11:16 AM, Borislav Petkov wrote:
> On Thu, Apr 14, 2011 at 11:04:43AM -0400, Prarit Bhargava wrote:
>> On 04/14/2011 11:00 AM, Borislav Petkov wrote:
>>> On Wed, Apr 13, 2011 at 01:37:05PM -0400, Borislav Petkov wrote:
>>>> In the worst case, we will report 32 CEs before panicking. For that case
>>>> we either do printk_once as Tony suggested or we ratelimit it. I'll
>>>> update the patch.
>>> Ok, how about the following, I ratelimit the printk to the default of 10
>>> messages per 5 seconds. I've also got the hardware MCE injection patches
>>> ready and will do some testing with them.
>> See my previous email ;) I think just putting in a printk_once after
>> the CE call to print_mce() in mce_panic() might be better? At least
>> that way we get the --ascii message for *EVERY* UC which IMO would be
>> nice...
> Are you sure? printk_once() is, as its name says, a one-time thing and
> it is implemented that way - a static bool counter which is once set and
> that's it. I.e., the "--ascii" message will be printed only once for the
> system's lifetime.

Oops ... I may have confused you because what I did was subtle. I
really should have explicitly pointed out what I did. Sorry, my bad.

From my patch (sorry for the cut-and-paste):

@@ -239,7 +227,10 @@ static void print_mce(struct mce *m)
* Print out human-readable details about the MCE error,
* (if the CPU has an implementation for that)
- atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, m);
+ ret = atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, m);
+ if (ret != NOTIFY_STOP && (m->status & MCI_STATUS_UC))
+ pr_emerg(HW_ERR "Run the above through 'mcelog --ascii' "
+ "to decode.\n");

This, of course, only outputs during UCs.


@@ -289,6 +280,8 @@ static void mce_panic(char *msg, struct mce *final,
char *exp)
if (!(m->status & MCI_STATUS_UC)) {
+ printk_once(KERN_EMERG HW_ERR "MCE Corrected
Error(s) "
+ "detected.");
if (!apei_err)
apei_err = apei_write_mce(m);
so we'll print "MCE Corrected Error(s)" _once_ if we go through this
path. Since there is no data to decode with mcelog, a nice little one
time message is probably the way to go :).


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