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SubjectRe: [PATCH] slab: add missing guard for kernel_map_pages() use
On Fri, May 22, 2009 at 06:20:40PM +0930, Ron wrote:
>
> All other uses of kernel_map_pages() are explicitly excluded without
> CONFIG_DEBUG_PAGEALLOC, this one should be too.
>
> Signed-off-by: Ron Lee <ron@debian.org>
>
>
> diff --git a/mm/slab.c b/mm/slab.c
> index 9a90b00..b5e5b27 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -2674,10 +2683,12 @@ static void cache_init_objs(struct kmem_cache *cachep,
> slab_error(cachep, "constructor overwrote the"
> " start of an object");
> }
> +#ifdef CONFIG_DEBUG_PAGEALLOC
> if ((cachep->buffer_size % PAGE_SIZE) == 0 &&
> OFF_SLAB(cachep) && cachep->flags & SLAB_POISON)
> kernel_map_pages(virt_to_page(objp),
> cachep->buffer_size / PAGE_SIZE, 0);
> +#endif
> #else
> if (cachep->ctor)
> cachep->ctor(objp);

Actually, no. I'm wrong on this one. The compiler will already take that
one away because kernel_map_pages() is an empty function in that case.

It's subtle, but this extra guard actually adds nothing (unless you consider
more #ifdefs to be 'clarifying');

Sorry for the extra noise,
Ron




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