linux-kernel - Re: [PATCH v2] generic-ipi: Initialize call_single

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Message-ID: <AANLkTi=cne0mSNOV0BC3X-SGeNOPPa5MSUf3L6yLJ1-t@mail.gmail.com>
Date:	Wed, 30 Mar 2011 23:19:50 +0800
From:	Américo Wang <xiyou.wangcong@...il.com>
To:	Takao Indoh <indou.takao@...fujitsu.com>
Cc:	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	Milton Miller <miltonm@....com>, Jens Axboe <axboe@...nel.dk>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...e.hu>, Vivek Goyal <vgoyal@...hat.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH v2] generic-ipi: Initialize call_single_queue before
 enabling interrupt

On Wed, Mar 30, 2011 at 12:35 AM, Takao Indoh
<indou.takao@...fujitsu.com> 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
>

Looks good to my eyes,

Reviewed-by: WANG Cong <xiyou.wangcong@...il.com>

Thanks.
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