On Thu, Jan 07, 2021 at 12:26:19AM +0000, Luck, Tony wrote:
> > Please see below for an updated patch.
>
> Yes. That worked:
>
> [ 78.946069] mce: mce_timed_out: MCE holdout CPUs (may include false
> positives): 24-47,120-143
> [ 78.946151] mce: mce_timed_out: MCE holdout CPUs (may include false
> positives): 24-47,120-143
> [ 78.946153] Kernel panic - not syncing: Timeout: Not all CPUs entered
> broadcast exception handler
>
> I guess that more than one CPU hit the timeout and so your new message was
> printed twice
> before the panic code took over?
Could well be.
It would be easy to add a flag that allowed only one CPU to print the
message. Does that make sense? (See off-the-cuff probably-broken
delta patch below for one approach.)
> Once again, the whole of socket 1 is MIA rather than just the pair of threads
> on one of the cores there.
> But that's a useful improvement (eliminating the other three sockets on this
> system).
>
> Tested-by: Tony Luck <tony.l...@intel.com>
Thank you very much! I will apply this.
Thanx, Paul
------------------------------------------------------------------------
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 7a6e1f3..b46ac56 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -882,6 +882,7 @@ static atomic_t mce_callin;
*/
static cpumask_t mce_present_cpus;
static cpumask_t mce_missing_cpus;
+static atomic_t mce_missing_cpus_gate;
/*
* Check if a timeout waiting for other CPUs happened.
@@ -900,7 +901,7 @@ static int mce_timed_out(u64 *t, const char *msg)
if (!mca_cfg.monarch_timeout)
goto out;
if ((s64)*t < SPINUNIT) {
- if (mca_cfg.tolerant <= 1) {
+ if (mca_cfg.tolerant <= 1 &&
!atomic_xchg(&mce_missing_cpus_gate, 1)) {
if (cpumask_andnot(&mce_missing_cpus, cpu_online_mask,
&mce_present_cpus))
pr_info("%s: MCE holdout CPUs (may include
false positives): %*pbl\n",
__func__,
cpumask_pr_args(&mce_missing_cpus));
@@ -1017,6 +1018,7 @@ static int mce_start(int *no_way_out)
*/
order = atomic_inc_return(&mce_callin);
cpumask_set_cpu(smp_processor_id(), &mce_present_cpus);
+ atomic_set(&mce_missing_cpus_gate, 0);
/*
* Wait for everyone.
@@ -1126,6 +1128,7 @@ static int mce_end(int order)
atomic_set(&global_nwo, 0);
atomic_set(&mce_callin, 0);
cpumask_clear(&mce_present_cpus);
+ atomic_set(&mce_missing_cpus_gate, 0);
barrier();
/*
@@ -2725,6 +2728,7 @@ static void mce_reset(void)
atomic_set(&mce_callin, 0);
atomic_set(&global_nwo, 0);
cpumask_clear(&mce_present_cpus);
+ atomic_set(&mce_missing_cpus_gate, 0);
}
static int fake_panic_get(void *data, u64 *val)
