linux-kernel - Re: [PATCH] Do not reserve crashkernel high memory if crashkernel low memory reserving failed

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Message-ID: <20150719134003.GC27557@nazgul.tnic>
Date:	Sun, 19 Jul 2015 15:40:03 +0200
From:	Borislav Petkov <bp@...e.de>
To:	Baoquan He <bhe@...hat.com>
Cc:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	akpm@...ux-foundation.org, jkosina@...e.cz, vgoyal@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Do not reserve crashkernel high memory if crashkernel
 low memory reserving failed

On Sun, Jul 19, 2015 at 07:07:44PM +0800, Baoquan He wrote:
> People reported that when allocating crashkernel memory using
> ",high" and ",low" syntax, there were cases where the reservation
> of the "high" portion succeeds, but the reservation of the "low"
> portion fails. Then kexec can load kdump kernel successfully, but
> the boot of kdump kernel fails as there's no low memory. This is
> because allocation of low memory for kdump kernel can fail on large
> systems for reasons. E.g it could be manually specified crashkernel
> low memory is too large to find in memblock region.
> 
> In this patch add return value for reserve_crashkernel_low. Then put
> the crashkernel low memory reserving earlier, just between finding
> the crashkernel high memory region and reserving crashkernel high
> memory. Then if crashkernel low memory reserving failed we do not
> reserve crashkernel high memory but return directly. Users can take
> measures when they found kdump kernel cann't be loaded successfully.
>
> Signed-off-by: Baoquan He <bhe@...hat.com>
> ---
>  arch/x86/kernel/setup.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)

...

> @@ -552,7 +552,7 @@ static void __init reserve_crashkernel_low(void)
>  		if (!auto_set)
>  			pr_info("crashkernel low reservation failed - No suitable area found.\n");
>  
> -		return;
> +		return EINVAL;

Error values are negative:

		return -EINVAL;

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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