linux-kernel - Re: [PATCH] ia64: disable SCHED_STACK_END

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Message-ID: <20181015201441.64f6816a@sf>
Date:   Mon, 15 Oct 2018 20:14:41 +0100
From:   Sergei Trofimovich <slyfox@...too.org>
To:     Tony Luck <tony.luck@...el.com>
Cc:     Fenghua Yu <fenghua.yu@...el.com>, linux-ia64@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ia64: disable SCHED_STACK_END_CHECK

On Fri, 14 Sep 2018 08:06:17 +0100
Sergei Trofimovich <slyfox@...too.org> wrote:

> SCHED_STACK_END_CHECK assumes stack grows in one direction.
> ia64 is a rare case where it is not.
> 
> As a result kernel fails at startup as:
>   Kernel panic - not syncing: corrupted stack end detected inside scheduler
> 
> The error does not find a real problem: it's register backing store
> is written on top of canary value.
> 
> Disable SCHED_STACK_END_CHECK on ia64 as there is no good
> place for canary without moving initial stack address.
> 
> CC: Tony Luck <tony.luck@...el.com>
> CC: Fenghua Yu <fenghua.yu@...el.com>
> CC: linux-ia64@...r.kernel.org
> CC: Andrew Morton <akpm@...ux-foundation.org>
> CC: linux-kernel@...r.kernel.org
> Signed-off-by: Sergei Trofimovich <slyfox@...too.org>
> ---
>  lib/Kconfig.debug | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 4966c4fbe7f7..a097dfe38d2b 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -1004,7 +1004,7 @@ config SCHEDSTATS
>  
>  config SCHED_STACK_END_CHECK
>  	bool "Detect stack corruption on calls to schedule()"
> -	depends on DEBUG_KERNEL
> +	depends on DEBUG_KERNEL && !IA64
>  	default n
>  	help
>  	  This option checks for a stack overrun on calls to schedule().
> -- 
> 2.19.0
> 

Ping.

-- 

  Sergei