On Wed, Nov 07, 2007 at 03:35:43AM +0100, Andi Kleen wrote:
> On Wednesday 07 November 2007 02:12, Andreas Herrmann wrote:
>
> > In cases where not all CPUs are brought up during
> > boot (e.g. using maxcpus and additional_cpus parameters)
> > mce_cpu_callback now returns NOTFIY_BAD because
> > for such CPUs cpu_data is not completely filled when
> > the notifier is called. Thus mce_create_device fails right
> > at its beginning:
> >
> > if (!mce_available(&cpu_data[cpu]))
> > return -EIO;
> >
> > As a quick fix I suggest to check boot_cpu_data for MCE.
>
> I guess it would be better to just move the device creation
> to after the CPU has booted. AKA call mce_create_dev() on CPU_ONLINE
> instead.
Yes, and this was the old behaviour. The mentioned patch changed it -
("do mce_create_device in CPU_UP_PREPARE instead of CPU_ONLINE").
Thinking twice about the problem it seems obvious that this part
of the patch should just be reverted.
Attached is a new fix (diff against 2.6.24-rc2).
Regards,
Andreas
--
[PATCH] x86: fix cpu hotplug regression (don't call mce_create_device on CPU_UP_PREPARE)
Fix regression introduced with d435d862baca3e25e5eec236762a43251b1e7ffc
("cpu hotplug: mce: fix cpu hotplug error handling").
For CPUs not brought up during boot (using maxcpus and additional_cpus
parameters) we don't know whether mce is supported or not at "CPU_UP_PREPARE"-time.
Thus mce_cpu_callback should be called after the CPU is online.
Signed-off-by: Andreas Herrmann <[email protected]>
---
arch/x86/kernel/cpu/mcheck/mce_64.c | 6 ++----
1 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/mcheck/mce_64.c b/arch/x86/kernel/cpu/mcheck/mce_64.c
index b9f802e..8e83070 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_64.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_64.c
@@ -855,12 +855,10 @@ mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
int err = 0;
switch (action) {
- case CPU_UP_PREPARE:
- case CPU_UP_PREPARE_FROZEN:
+ case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
err = mce_create_device(cpu);
break;
- case CPU_UP_CANCELED:
- case CPU_UP_CANCELED_FROZEN:
case CPU_DEAD:
case CPU_DEAD_FROZEN:
mce_remove_device(cpu);
--
1.5.3.4
-
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