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Commit 82584ef7 authored by Shaohua Li's avatar Shaohua Li Committed by Linus Torvalds
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[PATCH] x86: fix NMI with CPU hotplug 



With CPU hotplug enabled, NMI watchdog stoped working.  It appears the
violation is the cpu_online check in nmi handler.  local ACPI based NMI
watchdog is initialized before we set CPU online for APs.  It's quite
possible a NMI is fired before we set CPU online, and that's what happens
here.

Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
Acked-by: default avatarZwane Mwaikambo <zwane@arm.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent b3e55c72

arch/i386/kernel/traps.c

+0 −7
Original line number Diff line number Diff line
@@ -650,13 +650,6 @@ fastcall void do_nmi(struct pt_regs * regs, long error_code) 


	cpu = smp_processor_id();



#ifdef CONFIG_HOTPLUG_CPU

	if (!cpu_online(cpu)) {

		nmi_exit();

		return;

	}

#endif



	++nmi_count(cpu);



	if (!rcu_dereference(nmi_callback)(regs, cpu))