linux-kernel - Re: [PATCH] x86: suppress stack overrun message for init

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Message-ID: <20091121101709.GC2412@hack>
Date:	Sat, 21 Nov 2009 18:17:09 +0800
From:	Américo Wang <xiyou.wangcong@...il.com>
To:	Jan Beulich <JBeulich@...ell.com>
Cc:	mingo@...e.hu, tglx@...utronix.de, hpa@...or.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: suppress stack overrun message for init_task

On Fri, Nov 20, 2009 at 02:00:14PM +0000, Jan Beulich wrote:
>init_task doesn't get its stack end location set to STACK_END_MAGIC,
>and hence the message is confusing rather than helpful in this case.
>
>Signed-off-by: Jan Beulich <jbeulich@...ell.com>
>

Yeah, this is a good catch. STACK_END_MAGIC is written in fork(),
init is not forked.

However, isn't it better if we can do the same detection
for init too?


>---
> arch/x86/mm/fault.c |    2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>--- linux-2.6.32-rc8/arch/x86/mm/fault.c
>+++ 2.6.32-rc8-x86-init-task-stack/arch/x86/mm/fault.c
>@@ -658,7 +658,7 @@ no_context(struct pt_regs *regs, unsigne
> 	show_fault_oops(regs, error_code, address);
> 
> 	stackend = end_of_stack(tsk);
>-	if (*stackend != STACK_END_MAGIC)
>+	if (tsk != &init_task && *stackend != STACK_END_MAGIC)
> 		printk(KERN_ALERT "Thread overran stack, or stack corrupted\n");
> 
> 	tsk->thread.cr2		= address;
>
>
>
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