Re: [PATCH v2 03/10] slab: move up code to get kmem_cache_node in free_block()

From: David Rientjes
Date: Wed May 07 2014 - 17:30:13 EST


On Wed, 7 May 2014, George Spelvin wrote:

> diff --git a/mm/slab.c b/mm/slab.c
> index 388cb1ae6f..7fdc8df104 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -215,9 +215,9 @@ static inline void set_obj_pfmemalloc(void **objp)
> return;
> }
>
> -static inline void clear_obj_pfmemalloc(void **objp)
> +static inline void *clear_obj_pfmemalloc(void **objp)
> {
> - *objp = (void *)((unsigned long)*objp & ~SLAB_OBJ_PFMEMALLOC);
> + return *objp = (void *)((unsigned long)*objp & ~SLAB_OBJ_PFMEMALLOC);
> }
>
> /*
> @@ -809,10 +809,8 @@ static void *__ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
> if (unlikely(is_obj_pfmemalloc(objp))) {
> struct kmem_cache_node *n;
>
> - if (gfp_pfmemalloc_allowed(flags)) {
> - clear_obj_pfmemalloc(&objp);
> - return objp;
> - }
> + if (gfp_pfmemalloc_allowed(flags))
> + return clear_obj_pfmemalloc(&objp);
>
> /* The caller cannot use PFMEMALLOC objects, find another one */
> for (i = 0; i < ac->avail; i++) {
> @@ -833,9 +831,8 @@ static void *__ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
> if (!list_empty(&n->slabs_free) && force_refill) {
> struct page *page = virt_to_head_page(objp);
> ClearPageSlabPfmemalloc(page);
> - clear_obj_pfmemalloc(&objp);
> recheck_pfmemalloc_active(cachep, ac);
> - return objp;
> + return clear_obj_pfmemalloc(&objp);
> }
>
> /* No !PFMEMALLOC objects available */
> @@ -3362,17 +3359,12 @@ static void free_block(struct kmem_cache *cachep, void **objpp, int nr_objects,
> int node)
> {
> int i;
> - struct kmem_cache_node *n;
> + struct kmem_cache_node *n = cachep->node[node];
>
> for (i = 0; i < nr_objects; i++) {
> - void *objp;
> - struct page *page;
> -
> - clear_obj_pfmemalloc(&objpp[i]);
> - objp = objpp[i];
> + void *objp = clear_obj_pfmemalloc(&objpp[i]);
> + struct page *page = virt_to_head_page(objp);
>
> - page = virt_to_head_page(objp);
> - n = cachep->node[node];
> list_del(&page->lru);
> check_spinlock_acquired_node(cachep, node);
> slab_put_obj(cachep, page, objp, node);

I think this unnecessarily obfuscates the code.
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