Hi all, Actually this is a v2 patch but I post with new subject. The first post is here. [PATCH][KDUMP] Ignore spurious IPI http://www.gossamer-threads.com/lists/linux/kernel/1356389 The problem I found is that kdump(2nd kernel) sometimes hangs up due to pending IPI from 1st kernel. Kernel panic occurs because IPI comes before call_single_queue is initialized, so this patch moves init_call_single_data() so that it can be called before local_irq_enable(). The details of the problem is below. (1) 2nd kernel boot up (2) A pending IPI from 1st kernel comes after unmasking interrupts at the following point. asmlinkage void __init start_kernel(void) { (snip) time_init(); profile_init(); if (!irqs_disabled()) printk(KERN_CRIT "start_kernel(): bug: interrupts were " "enabled early\n"); early_boot_irqs_disabled = false; local_irq_enable(); <=======================================HERE (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. Any comments would be appreciated. Signed-off-by: Takao Indoh <indou.takao at jp.fujitsu.com> --- include/linux/smp.h | 1 + init/main.c | 1 + kernel/smp.c | 18 +++++++++++------- 3 files changed, 13 insertions(+), 7 deletions(-) diff --git a/include/linux/smp.h b/include/linux/smp.h index 6dc95ca..0b81bba 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -114,6 +114,7 @@ int on_each_cpu(smp_call_func_t func, void *info, int wait); void smp_prepare_boot_cpu(void); extern unsigned int setup_max_cpus; +void init_call_single_data(void); #else /* !SMP */ diff --git a/init/main.c b/init/main.c index 33c37c3..02a7617 100644 --- a/init/main.c +++ b/init/main.c @@ -631,6 +631,7 @@ asmlinkage void __init start_kernel(void) printk(KERN_CRIT "start_kernel(): bug: interrupts were " "enabled early\n"); early_boot_irqs_disabled = false; + init_call_single_data(); local_irq_enable(); /* Interrupts are enabled now so all GFP allocations are safe. */ diff --git a/kernel/smp.c b/kernel/smp.c index 7cbd0f2..f119610 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -74,9 +74,19 @@ static struct notifier_block __cpuinitdata hotplug_cfd_notifier = { .notifier_call = hotplug_cfd, }; -static int __cpuinit init_call_single_data(void) +static int __cpuinit init_hotplug_cfd(void) { void *cpu = (void *)(long)smp_processor_id(); + + hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu); + register_cpu_notifier(&hotplug_cfd_notifier); + + return 0; +} +early_initcall(init_hotplug_cfd); + +void __init init_call_single_data(void) +{ int i; for_each_possible_cpu(i) { @@ -85,13 +95,7 @@ static int __cpuinit init_call_single_data(void) raw_spin_lock_init(&q->lock); INIT_LIST_HEAD(&q->list); } - - 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
