linux-kernel - Re: linux-next: build failure after merge of the final tree (slab tree related)

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Message-ID: <alpine.DEB.2.00.1008251656390.22018@chino.kir.corp.google.com>
Date:	Wed, 25 Aug 2010 17:01:27 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Christoph Lameter <cl@...ux.com>
cc:	Pekka Enberg <penberg@...helsinki.fi>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	linux-next@...r.kernel.org, linux-kernel@...r.kernel.org,
	Tejun Heo <tj@...nel.org>
Subject: Re: linux-next: build failure after merge of the final tree (slab
 tree related)

On Wed, 25 Aug 2010, Christoph Lameter wrote:

> Since the percpu allocator does not provide early allocation in UP
> mode (only in SMP configurations) use __get_free_page() to improvise
> a compound page allocation that can be later freed via kfree().
> 
> Compound pages will be released when the cpu caches are resized.
> 
> Signed-off-by: Christoph Lameter <cl@...ux.com>
> 
> ---
>  mm/slub.c |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> Index: linux-2.6/mm/slub.c
> ===================================================================
> --- linux-2.6.orig/mm/slub.c	2010-08-24 20:07:12.766010774 -0500
> +++ linux-2.6/mm/slub.c	2010-08-24 20:15:46.304130417 -0500
> @@ -2064,8 +2064,24 @@
> 
>  static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
>  {
> +#ifdef CONFIG_SMP
> +	/*
> +	 * Will use reserve that does not require slab operation during
> +	 * early boot.
> +	 */
>  	BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
>  			SLUB_PAGE_SHIFT * sizeof(struct kmem_cache_cpu));
> +#else
> +	/*
> +	 * Special hack for UP mode. allocpercpu() falls back to kmalloc
> +	 * operations. So we cannot use that before the slab allocator is up
> +	 * Simply get the smallest possible compound page. The page will be
> +	 * released via kfree() when the cpu caches are resized later.
> +	 */
> +	if (slab_state < UP)
> +		s->cpu_slab = (__percpu void *)__get_free_page(GFP_NOWAIT, 1);

__get_free_pages() takes an order argument.

> +	else
> +#endif
> 
>  	s->cpu_slab = alloc_percpu(struct kmem_cache_cpu);
> 
--
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