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Date: Wed, 22 Nov 2023 10:09:04 +0900
From: Hyeonggon Yoo <42.hyeyoo@...il.com>
To: chengming.zhou@...ux.dev
Cc: vbabka@...e.cz, cl@...ux.com, penberg@...nel.org,
rientjes@...gle.com, iamjoonsoo.kim@....com,
akpm@...ux-foundation.org, roman.gushchin@...ux.dev,
linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Chengming Zhou <zhouchengming@...edance.com>
Subject: Re: [PATCH v5 2/9] slub: Change get_partial() interfaces to return slab
On Thu, Nov 2, 2023 at 12:24 PM <chengming.zhou@...ux.dev> wrote:
>
> From: Chengming Zhou <zhouchengming@...edance.com>
>
> We need all get_partial() related interfaces to return a slab, instead
> of returning the freelist (or object).
>
> Use the partial_context.object to return back freelist or object for
> now. This patch shouldn't have any functional changes.
>
> Suggested-by: Vlastimil Babka <vbabka@...e.cz>
> Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
> Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
> Tested-by: Hyeonggon Yoo <42.hyeyoo@...il.com>
> ---
> mm/slub.c | 63 +++++++++++++++++++++++++++++--------------------------
> 1 file changed, 33 insertions(+), 30 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 0b0fdc8c189f..03384cd965c5 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -204,9 +204,9 @@ DEFINE_STATIC_KEY_FALSE(slub_debug_enabled);
>
> /* Structure holding parameters for get_partial() call chain */
> struct partial_context {
> - struct slab **slab;
> gfp_t flags;
> unsigned int orig_size;
> + void *object;
> };
>
> static inline bool kmem_cache_debug(struct kmem_cache *s)
> @@ -2269,10 +2269,11 @@ static inline bool pfmemalloc_match(struct slab *slab, gfp_t gfpflags);
> /*
> * Try to allocate a partial slab from a specific node.
> */
> -static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
> - struct partial_context *pc)
> +static struct slab *get_partial_node(struct kmem_cache *s,
> + struct kmem_cache_node *n,
> + struct partial_context *pc)
> {
> - struct slab *slab, *slab2;
> + struct slab *slab, *slab2, *partial = NULL;
> void *object = NULL;
> unsigned long flags;
> unsigned int partial_slabs = 0;
> @@ -2288,27 +2289,28 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
>
> spin_lock_irqsave(&n->list_lock, flags);
> list_for_each_entry_safe(slab, slab2, &n->partial, slab_list) {
> - void *t;
> -
> if (!pfmemalloc_match(slab, pc->flags))
> continue;
>
> if (IS_ENABLED(CONFIG_SLUB_TINY) || kmem_cache_debug(s)) {
> object = alloc_single_from_partial(s, n, slab,
> pc->orig_size);
> - if (object)
> + if (object) {
> + partial = slab;
> + pc->object = object;
> break;
> + }
> continue;
> }
>
> - t = acquire_slab(s, n, slab, object == NULL);
> - if (!t)
> + object = acquire_slab(s, n, slab, object == NULL);
> + if (!object)
> break;
>
> - if (!object) {
> - *pc->slab = slab;
> + if (!partial) {
> + partial = slab;
> + pc->object = object;
> stat(s, ALLOC_FROM_PARTIAL);
> - object = t;
> } else {
> put_cpu_partial(s, slab, 0);
> stat(s, CPU_PARTIAL_NODE);
> @@ -2324,20 +2326,21 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
>
> }
> spin_unlock_irqrestore(&n->list_lock, flags);
> - return object;
> + return partial;
> }
>
> /*
> * Get a slab from somewhere. Search in increasing NUMA distances.
> */
> -static void *get_any_partial(struct kmem_cache *s, struct partial_context *pc)
> +static struct slab *get_any_partial(struct kmem_cache *s,
> + struct partial_context *pc)
> {
> #ifdef CONFIG_NUMA
> struct zonelist *zonelist;
> struct zoneref *z;
> struct zone *zone;
> enum zone_type highest_zoneidx = gfp_zone(pc->flags);
> - void *object;
> + struct slab *slab;
> unsigned int cpuset_mems_cookie;
>
> /*
> @@ -2372,8 +2375,8 @@ static void *get_any_partial(struct kmem_cache *s, struct partial_context *pc)
>
> if (n && cpuset_zone_allowed(zone, pc->flags) &&
> n->nr_partial > s->min_partial) {
> - object = get_partial_node(s, n, pc);
> - if (object) {
> + slab = get_partial_node(s, n, pc);
> + if (slab) {
> /*
> * Don't check read_mems_allowed_retry()
> * here - if mems_allowed was updated in
> @@ -2381,7 +2384,7 @@ static void *get_any_partial(struct kmem_cache *s, struct partial_context *pc)
> * between allocation and the cpuset
> * update
> */
> - return object;
> + return slab;
> }
> }
> }
> @@ -2393,17 +2396,18 @@ static void *get_any_partial(struct kmem_cache *s, struct partial_context *pc)
> /*
> * Get a partial slab, lock it and return it.
> */
> -static void *get_partial(struct kmem_cache *s, int node, struct partial_context *pc)
> +static struct slab *get_partial(struct kmem_cache *s, int node,
> + struct partial_context *pc)
> {
> - void *object;
> + struct slab *slab;
> int searchnode = node;
>
> if (node == NUMA_NO_NODE)
> searchnode = numa_mem_id();
>
> - object = get_partial_node(s, get_node(s, searchnode), pc);
> - if (object || node != NUMA_NO_NODE)
> - return object;
> + slab = get_partial_node(s, get_node(s, searchnode), pc);
> + if (slab || node != NUMA_NO_NODE)
> + return slab;
>
> return get_any_partial(s, pc);
> }
> @@ -3213,10 +3217,10 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
> new_objects:
>
> pc.flags = gfpflags;
> - pc.slab = &slab;
> pc.orig_size = orig_size;
> - freelist = get_partial(s, node, &pc);
> - if (freelist) {
> + slab = get_partial(s, node, &pc);
> + if (slab) {
> + freelist = pc.object;
> if (kmem_cache_debug(s)) {
> /*
> * For debug caches here we had to go through
> @@ -3408,12 +3412,11 @@ static void *__slab_alloc_node(struct kmem_cache *s,
> void *object;
>
> pc.flags = gfpflags;
> - pc.slab = &slab;
> pc.orig_size = orig_size;
> - object = get_partial(s, node, &pc);
> + slab = get_partial(s, node, &pc);
>
> - if (object)
> - return object;
> + if (slab)
> + return pc.object;
>
> slab = new_slab(s, gfpflags, node);
> if (unlikely(!slab)) {
Looks good to me,
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@...il.com>
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