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Date: Wed, 30 Mar 2011 11:48:34 -0400
From: Neil Horman <nhorman@...hat.com>
To: Takao Indoh <indou.takao@...fujitsu.com>
Cc: linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
Jens Axboe <axboe@...nel.dk>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Milton Miller <miltonm@....com>,
WANG Cong <xiyou.wangcong@...il.com>,
Ingo Molnar <mingo@...e.hu>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Vivek Goyal <vgoyal@...hat.com>
Subject: Re: [PATCH v2] generic-ipi: Initialize call_single_queue before
enabling interrupt
On Tue, Mar 29, 2011 at 12:35:04PM -0400, Takao Indoh wrote:
> Hi all,
>
> This patch renames init_call_single_data() to call_function_init() and
> calls it in start_kernel() so that call_single_queue can be initialized
> before enabling interrupt.
>
> There is a problem 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. The details are as follows.
> (1) 2nd kernel boot 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().
>
> v2:
> - Rename init_call_single_data() to call_function_init() and calls it in
> start_kernel()
> - Change insert position in start_kernel().
> - Adjust for CONFIG_SMP/CONFIG_USE_GENERIC_SMP_HELPERS options
> - Rebased to Linus's latest tree
>
> v1:
> https://lkml.org/lkml/2011/3/25/317
> - Divide init_call_single_data() into two functions,
> o init_call_single_data: initialize call_single_queue
> o init_hotplug_cfd: initialize hotplug_cfd_notifier
> And call init_call_single_data before local_irq_enable() in
> start_kernel().
>
> v0:
> https://lkml.org/lkml/2011/3/23/417
> - In generic_smp_call_function_single_interrupt(), check if
> call_single_queue was initialized or not, and just return if not
> initialized.
>
> Signed-off-by: Takao Indoh <indou.takao@...fujitsu.com>
> ---
> include/linux/smp.h | 5 ++++-
> init/main.c | 1 +
> kernel/smp.c | 5 +----
> 3 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/smp.h b/include/linux/smp.h
> index 74243c8..4fb3eac 100644
> --- a/include/linux/smp.h
> +++ b/include/linux/smp.h
> @@ -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
>
> /*
> @@ -144,7 +147,7 @@ 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,
> diff --git a/init/main.c b/init/main.c
> index 4a9479e..12821d1 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -539,6 +539,7 @@ 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");
> diff --git a/kernel/smp.c b/kernel/smp.c
> index 73a1951..fb67dfa 100644
> --- a/kernel/smp.c
> +++ b/kernel/smp.c
> @@ -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
>
Acked-by: Neil Horman <nhorman@...driver.com>
> _______________________________________________
> kexec mailing list
> kexec@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
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