linux-kernel - Re: Broken "cpualloc: the allocator" patch

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Message-ID: <20081106023059.GA3555@cmpxchg.org>
Date:	Thu, 6 Nov 2008 03:30:59 +0100
From:	Johannes Weiner <hannes@...xchg.org>
To:	Pekka J Enberg <penberg@...helsinki.fi>
Cc:	Alexey Dobriyan <adobriyan@...il.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	rusty@...tcorp.com.au, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: Broken "cpualloc: the allocator" patch

On Wed, Nov 05, 2008 at 10:57:11AM +0200, Pekka J Enberg wrote:
> Yup, makes sense. PERCPU_MODULE_RESERVE is set to zero if !CONFIG_MODULES. 
> Is there a reason we don't do something like this in bootmem allocator? 
> Hannes?
> 		Pekka
> 
> diff --git a/mm/bootmem.c b/mm/bootmem.c
> index ac5a891..ee6431f 100644
> --- a/mm/bootmem.c
> +++ b/mm/bootmem.c
> @@ -435,7 +435,9 @@ static void * __init alloc_bootmem_core(struct bootmem_data *bdata,
>  	unsigned long fallback = 0;
>  	unsigned long min, max, start, sidx, midx, step;
>  
> -	BUG_ON(!size);
> +	if (!size)
> +		return NULL;
> +
>  	BUG_ON(align & (align - 1));
>  	BUG_ON(limit && goal + size > limit);

That comes from the original code, I have no strong opinion on it.

Christoph already fixed it up by making PERCPU_MODULE_RESERVE always
!0 and it looks like all other callsites are happy with the current
behaviour.

	Hannes
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