Re: [PATCH] Fix section mismatch

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 11 May 2007 17:35:22 +0200
Bernhard Walle <bwalle@suse.de> wrote:

> This patch fixes following compile warning:
> 
> --------- >8 --------
> WARNING: mm/built-in.o - Section mismatch: reference to .init.text: from .text
> between 'kmem_cache_create' (at offset 0x2167b) and 'drain_alien_cache'
> 
> WARNING: mm/built-in.o - Section mismatch: reference to .init.text: from .text
> between 'kmem_cache_create' (at offset 0x216c1) and 'drain_alien_cache'
> --------- 8< --------
> 
> set_up_list3s() can be called from setup_cpu_cache() [mm/slab.c] which is not
> an init function.
> 
> 

Yes.  This warning is a false positive.  See

static int setup_cpu_cache(struct kmem_cache *cachep)
{
	if (g_cpucache_up == FULL)
		return enable_cpucache(cachep);

	if (g_cpucache_up == NONE) {
		...
		set_up_list3s(cachep, SIZE_AC);

The g_cpucache_up==NONE state only exists before we have run free_initmem().

There is a similar false-positive down in acpi somewhere.

I think Sam is working on a scheme whereby we can add annotation to quash
the warnings in cases such as this.


> 
> ---
>  mm/slab.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -305,7 +305,7 @@ struct kmem_list3 {
>   * Need this for bootstrapping a per node allocator.
>   */
>  #define NUM_INIT_LISTS (2 * MAX_NUMNODES + 1)
> -struct kmem_list3 __initdata initkmem_list3[NUM_INIT_LISTS];
> +struct kmem_list3 initkmem_list3[NUM_INIT_LISTS];
>  #define	CACHE_CACHE 0
>  #define	SIZE_AC 1
>  #define	SIZE_L3 (1 + MAX_NUMNODES)
> @@ -1960,7 +1960,7 @@ static void slab_destroy(struct kmem_cac
>   * For setting up all the kmem_list3s for cache whose buffer_size is same as
>   * size of kmem_list3.
>   */
> -static void __init set_up_list3s(struct kmem_cache *cachep, int index)
> +static void set_up_list3s(struct kmem_cache *cachep, int index)
>  {
>  	int node;

That'll shut it up, but we'll use more memory at runtime.