linux-kernel - Re: [PATCH -v2] x86: allocate cpumask during check irq vectors

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Message-ID: <20140125080232.GA20935@gmail.com>
Date:	Sat, 25 Jan 2014 09:02:32 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Prarit Bhargava <prarit@...hat.com>
Subject: Re: [PATCH -v2] x86: allocate cpumask during check irq vectors


* Yinghai Lu <yinghai@...nel.org> wrote:

> Fix warning:
> arch/x86/kernel/irq.c: In function check_irq_vectors_for_cpu_disable:
> arch/x86/kernel/irq.c:337:1: warning: the frame size of 2052 bytes is larger than 2048 bytes
> 
> when NR_CPUS=8192
> 
> We should use zalloc_cpumask_var() instead.
> 
> -v2: update to GFP_ATOMIC instead and free the allocated cpumask at last.
> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Cc: Prarit Bhargava <prarit@...hat.com>
> 
> ---
>  arch/x86/kernel/irq.c |   24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)
> 
> Index: linux-2.6/arch/x86/kernel/irq.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/irq.c
> +++ linux-2.6/arch/x86/kernel/irq.c
> @@ -277,11 +277,18 @@ int check_irq_vectors_for_cpu_disable(vo
>  	unsigned int this_cpu, vector, this_count, count;
>  	struct irq_desc *desc;
>  	struct irq_data *data;
> -	struct cpumask affinity_new, online_new;
> +	cpumask_var_t affinity_new, online_new;
> +
> +	if (!alloc_cpumask_var(&affinity_new, GFP_ATOMIC))
> +		return -ENOMEM;
> +	if (!alloc_cpumask_var(&online_new, GFP_ATOMIC)) {
> +		free_cpumask_var(affinity_new);
> +		return -ENOMEM;
> +	}

Atomic allocations can fail easily if the system is under duress.

Thanks,

	Ingo
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