linux-kernel - Re: [PATCH] kernel/panic/kexec: fix "crash_kexec_post

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Date:	Fri, 20 Feb 2015 17:31:21 +0900
From:	"HATAYAMA, Daisuke" <d.hatayama@...fujitsu.com>
To:	ebiederm@...ssion.com, vgoyal@...hat.com
CC:	masami.hiramatsu.pt@...achi.com, linux-kernel@...r.kernel.org,
	kexec@...ts.infradead.org
Subject: Re: [PATCH] kernel/panic/kexec: fix "crash_kexec_post_notifiers"
 option issue in oops path

Hello Eric, Vivek,

Do you have any comment to this patch?

On 2015/02/05 17:59, HATAYAMA Daisuke wrote:
> The commit f06e5153f4ae2e2f3b0300f0e260e40cb7fefd45 introduced
> "crash_kexec_post_notifiers" kernel boot option, which toggles
> wheather panic() calls crash_kexec() before or after panic_notifiers
> and dump kmsg.
>
> The problem is that the commit overlooks panic_on_oops kernel boot
> option. If it is enabled, crash_kexec() is called directly without
> going through panic() in oops path.
>
> To fix this issue, this patch adds a check to
> "crash_kexec_post_notifiers" in the condition of kexec_should_crash().
>
> Signed-off-by: HATAYAMA Daisuke <d.hatayama@...fujitsu.com>
> ---
>   include/linux/kernel.h | 3 +++
>   kernel/kexec.c         | 2 ++
>   kernel/panic.c         | 2 +-
>   3 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 64ce58b..f47379f 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -426,6 +426,9 @@ extern int panic_on_unrecovered_nmi;
>   extern int panic_on_io_nmi;
>   extern int panic_on_warn;
>   extern int sysctl_panic_on_stackoverflow;
> +
> +extern bool crash_kexec_post_notifiers;
> +
>   /*
>    * Only to be used by arch init code. If the user over-wrote the default
>    * CONFIG_PANIC_TIMEOUT, honor it.
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index 9a8a01a..0ecf252 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -84,6 +84,8 @@ struct resource crashk_low_res = {
>
>   int kexec_should_crash(struct task_struct *p)
>   {
> +	if (crash_kexec_post_notifiers)
> +		return 0;
>   	if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
>   		return 1;
>   	return 0;
> diff --git a/kernel/panic.c b/kernel/panic.c
> index 4d8d6f9..6582546 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -32,7 +32,7 @@ static unsigned long tainted_mask;
>   static int pause_on_oops;
>   static int pause_on_oops_flag;
>   static DEFINE_SPINLOCK(pause_on_oops_lock);
> -static bool crash_kexec_post_notifiers;
> +bool crash_kexec_post_notifiers;
>   int panic_on_warn __read_mostly;
>
>   int panic_timeout = CONFIG_PANIC_TIMEOUT;
>

-- 
Thanks.
HATAYAMA, Daisuke

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