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SubjectRe: [PATCH -mm 4/6] slqb: record slab's start address in slqb_page
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On Tue, 2009-03-03 at 21:44 +0800, Lai Jiangshan wrote:
> slqb's slab is coloring, it's will be useful that record the
> color value or start address in struct slqb_page.
>
> This fix adds a field in struct slqb_page to record slab's
> start address, It will be used by kfree_rcu().
>
>
> struct slqb_page has a field:
> struct kmem_cache_list *list;
>
> the corresponding field in struct page is:
>
> union {
> struct {
> unsigned long private;
> struct address_space *mapping;
> };
> struct kmem_cache *slab;
> struct page *first_page;
> };
>
> It's large than 'struct kmem_cache_list *list;'
> *So we are safe to add a field in struct page.*
>
>
> (This field will not become a burden in future:)
> struct page is very small, this fix uses the last room of
> struct page. But if we have to add a more important
> field in struct slqb_page in future, We can record slab's
> color value in slqb_page instead of start address.
> like this:
> struct {
> unsigned long flags;
> atomic_t _count;
> u16 inuse; /* use u16 instead */
> u16 color; /* of unsigned int */
> void *a_more_important_field;
> struct kmem_cache_list *list;
> void **freelist;
> union {
> struct list_head lru;
> struct rcu_head rcu_head;
> };
> };
>
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> ---
> diff --git a/mm/slqb.c b/mm/slqb.c
> index 48bdf3b..c258ddc 100644
> --- a/mm/slqb.c
> +++ b/mm/slqb.c
> @@ -41,6 +41,7 @@ struct slqb_page {
> unsigned long flags; /* mandatory */
> atomic_t _count; /* mandatory */
> unsigned int inuse; /* Nr of objects */
> + void *s_mem; /* start address */
> struct kmem_cache_list *list; /* Pointer to list */
> void **freelist; /* LIFO freelist */
> union {
> @@ -1010,6 +1011,7 @@ static struct slqb_page *new_slab_page(struct kmem_cache *s,
> }
> set_freepointer(s, last, NULL);
>
> + page->s_mem = start;
> page->freelist = start;
> page->inuse = 0;
> out:

I am okay with this but I think Nick was against it. Nick?

Pekka



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