From: Borislav Petkov <b...@suse.de> Subject: [PATCH] x86, MCE: Robustify mcheck_init_device
BorisO reports that misc_register() fails often on xen. The current code unregisters the CPU hotplug notifier in that case. If then a CPU is offlined and onlined back again, we end up with a second timer running on that CPU, leading to soft lockups and system hangs. So let's leave the hotcpu notifier always registered - even if mce_device_create failed for some cores and never unreg it so that we can deal with the timer handling accordingly. Reported-and-Tested-by: Boris Ostrovsky <boris.ostrov...@oracle.com> Link: http://lkml.kernel.org/r/1403274493-1371-1-git-send-email-boris.ostrov...@oracle.com Signed-off-by: Borislav Petkov <b...@suse.de> --- arch/x86/kernel/cpu/mcheck/mce.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index bb92f38153b2..9a79c8dbd8e8 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -2451,6 +2451,12 @@ static __init int mcheck_init_device(void) for_each_online_cpu(i) { err = mce_device_create(i); if (err) { + /* + * Register notifier anyway (and do not unreg it) so + * that we don't leave undeleted timers, see notifier + * callback above. + */ + __register_hotcpu_notifier(&mce_cpu_notifier); cpu_notifier_register_done(); goto err_device_create; } @@ -2471,10 +2477,6 @@ static __init int mcheck_init_device(void) err_register: unregister_syscore_ops(&mce_syscore_ops); - cpu_notifier_register_begin(); - __unregister_hotcpu_notifier(&mce_cpu_notifier); - cpu_notifier_register_done(); - err_device_create: /* * We didn't keep track of which devices were created above, but -- 2.0.0 -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
