On Mon, 28 Sep 2015, Jesper Dangaard Brouer wrote:
> diff --git a/mm/slub.c b/mm/slub.c
> index 1cf98d89546d..13b5f53e4840 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -675,11 +675,18 @@ static void init_object(struct kmem_cache *s, void *object, u8 val)
> {
> u8 *p = object;
>
> + /* Freepointer not overwritten as SLAB_POISON moved it after object */
> if (s->flags & __OBJECT_POISON) {
> memset(p, POISON_FREE, s->object_size - 1);
> p[s->object_size - 1] = POISON_END;
> }
>
> + /*
> + * If both SLAB_RED_ZONE and SLAB_POISON are enabled, then
> + * freepointer is still safe, as then s->offset equals
> + * s->inuse and below redzone is after s->object_size and only
> + * area between s->object_size and s->inuse.
> + */
> if (s->flags & SLAB_RED_ZONE)
> memset(p + s->object_size, val, s->inuse - s->object_size);
> }
Are these comments really adding something? This is basic metadata
handling for SLUB that is commented on elsehwere.
> @@ -2584,9 +2646,14 @@ EXPORT_SYMBOL(kmem_cache_alloc_node_trace);
> * So we still attempt to reduce cache line usage. Just take the slab
> * lock and free the item. If there is no additional partial page
> * handling required then we can return immediately.
> + *
> + * Bulk free of a freelist with several objects (all pointing to the
> + * same page) possible by specifying freelist_head ptr and object as
> + * tail ptr, plus objects count (cnt).
> */
> static void __slab_free(struct kmem_cache *s, struct page *page,
> - void *x, unsigned long addr)
> + void *x, unsigned long addr,
> + void *freelist_head, int cnt)
Do you really need separate parameters for freelist_head? If you just want
to deal with one object pass it as freelist_head and set cnt = 1?
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