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Commit d8ad7d11 authored by Takao Indoh's avatar Takao Indoh Committed by Ingo Molnar
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generic-ipi: Fix kexec boot crash by initializing call_single_queue before enabling interrupts 



There is a problem that kdump(2nd kernel) sometimes hangs up due
to a pending IPI from 1st kernel. Kernel panic occurs because IPI
comes before call_single_queue is initialized.

To fix the crash, rename init_call_single_data() to call_function_init()
and call it in start_kernel() so that call_single_queue can be
initialized before enabling interrupts.

The details of the crash are:

 (1) 2nd kernel boots up

 (2) A pending IPI from 1st kernel comes when irqs are first enabled
     in start_kernel().

 (3) Kernel tries to handle the interrupt, but call_single_queue
     is not initialized yet at this point. As a result, in the
     generic_smp_call_function_single_interrupt(), NULL pointer
     dereference occurs when list_replace_init() tries to access
     &q->list.next.

Therefore this patch changes the name of init_call_single_data()
to call_function_init() and calls it before local_irq_enable()
in start_kernel().

Signed-off-by: default avatarTakao Indoh <indou.takao@jp.fujitsu.com>
Reviewed-by: default avatarWANG Cong <xiyou.wangcong@gmail.com>
Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Milton Miller <miltonm@bga.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: kexec@lists.infradead.org
Link: http://lkml.kernel.org/r/D6CBEE2F420741indou.takao@jp.fujitsu.com


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent eb96c925

include/linux/smp.h

+4 −1
Original line number Diff line number Diff line
@@ -85,12 +85,15 @@ int smp_call_function_any(const struct cpumask *mask, 
 * Generic and arch helpers

 */

#ifdef CONFIG_USE_GENERIC_SMP_HELPERS

void __init call_function_init(void);

void generic_smp_call_function_single_interrupt(void);

void generic_smp_call_function_interrupt(void);

void ipi_call_lock(void);

void ipi_call_unlock(void);

void ipi_call_lock_irq(void);

void ipi_call_unlock_irq(void);

#else

static inline void call_function_init(void) { }

#endif



/*
@@ -134,7 +137,7 @@ static inline void smp_send_reschedule(int cpu) { } 
#define smp_prepare_boot_cpu()			do {} while (0)

#define smp_call_function_many(mask, func, info, wait) \

			(up_smp_call_function(func, info))

static inline void init_call_single_data(void) { }

static inline void call_function_init(void) { }



static inline int

smp_call_function_any(const struct cpumask *mask, smp_call_func_t func,

init/main.c

+1 −0
Original line number Diff line number Diff line
@@ -542,6 +542,7 @@ asmlinkage void __init start_kernel(void) 
	timekeeping_init();

	time_init();

	profile_init();

	call_function_init();

	if (!irqs_disabled())

		printk(KERN_CRIT "start_kernel(): bug: interrupts were "

				 "enabled early\n");

kernel/smp.c

+1 −4
Original line number Diff line number Diff line
@@ -74,7 +74,7 @@ static struct notifier_block __cpuinitdata hotplug_cfd_notifier = { 
	.notifier_call		= hotplug_cfd,

};



static int __cpuinit init_call_single_data(void)

void __init call_function_init(void)

{

	void *cpu = (void *)(long)smp_processor_id();

	int i;
@@ -88,10 +88,7 @@ static int __cpuinit init_call_single_data(void) 


	hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);

	register_cpu_notifier(&hotplug_cfd_notifier);



	return 0;

}

early_initcall(init_call_single_data);



/*

 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources