Re: [PATCH 10/20] mm: zswap: function ordering: pool alloc & free

From: Nhat Pham
Date: Tue Jan 30 2024 - 14:31:50 EST

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In reply to: Johannes Weiner: "[PATCH 10/20] mm: zswap: function ordering: pool alloc & free"
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On Mon, Jan 29, 2024 at 5:42 PM Johannes Weiner <hannes@xxxxxxxxxxx> wrote:
>
> The function ordering in zswap.c is a little chaotic, which requires
> jumping in unexpected directions when following related code. This is
> a series of patches that brings the file into the following order:
>
> - pool functions
> - lru functions
> - rbtree functions
> - zswap entry functions
> - compression/backend functions
> - writeback & shrinking functions
> - store, load, invalidate, swapon, swapoff
> - debugfs
> - init

This ordering seems reasonable to me. Then again, we don't have any
coherent ordering of functions, so anything would be an improvement :)

>
> But it has to be split up such the moving still produces halfway
> readable diffs.
>
> In this patch, move pool allocation and freeing functions.
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Reviewed-by: Nhat Pham <nphamcs@xxxxxxxxx>

> ---
> mm/zswap.c | 297 +++++++++++++++++++++++++++--------------------------
> 1 file changed, 152 insertions(+), 145 deletions(-)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 082d076a758d..805d9a35f633 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -320,6 +320,158 @@ static void zswap_update_total_size(void)
> zswap_pool_total_size = total;
> }
>
> +/*********************************
> +* pool functions
> +**********************************/
> +
> +static void zswap_alloc_shrinker(struct zswap_pool *pool);
> +static void shrink_worker(struct work_struct *w);
> +
> +static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
> +{
> + int i;
> + struct zswap_pool *pool;
> + char name[38]; /* 'zswap' + 32 char (max) num + \0 */
> + gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
> + int ret;
> +
> + if (!zswap_has_pool) {
> + /* if either are unset, pool initialization failed, and we
> + * need both params to be set correctly before trying to
> + * create a pool.
> + */
> + if (!strcmp(type, ZSWAP_PARAM_UNSET))
> + return NULL;
> + if (!strcmp(compressor, ZSWAP_PARAM_UNSET))
> + return NULL;
> + }
> +
> + pool = kzalloc(sizeof(*pool), GFP_KERNEL);
> + if (!pool)
> + return NULL;
> +
> + for (i = 0; i < ZSWAP_NR_ZPOOLS; i++) {
> + /* unique name for each pool specifically required by zsmalloc */
> + snprintf(name, 38, "zswap%x",
> + atomic_inc_return(&zswap_pools_count));
> +
> + pool->zpools[i] = zpool_create_pool(type, name, gfp);
> + if (!pool->zpools[i]) {
> + pr_err("%s zpool not available\n", type);
> + goto error;
> + }
> + }
> + pr_debug("using %s zpool\n", zpool_get_type(pool->zpools[0]));
> +
> + strscpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
> +
> + pool->acomp_ctx = alloc_percpu(*pool->acomp_ctx);
> + if (!pool->acomp_ctx) {
> + pr_err("percpu alloc failed\n");
> + goto error;
> + }
> +
> + ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE,
> + &pool->node);
> + if (ret)
> + goto error;
> +
> + zswap_alloc_shrinker(pool);
> + if (!pool->shrinker)
> + goto error;
> +
> + pr_debug("using %s compressor\n", pool->tfm_name);
> +
> + /* being the current pool takes 1 ref; this func expects the
> + * caller to always add the new pool as the current pool
> + */
> + kref_init(&pool->kref);
> + INIT_LIST_HEAD(&pool->list);
> + if (list_lru_init_memcg(&pool->list_lru, pool->shrinker))
> + goto lru_fail;
> + shrinker_register(pool->shrinker);
> + INIT_WORK(&pool->shrink_work, shrink_worker);
> + atomic_set(&pool->nr_stored, 0);
> +
> + zswap_pool_debug("created", pool);
> +
> + return pool;
> +
> +lru_fail:
> + list_lru_destroy(&pool->list_lru);
> + shrinker_free(pool->shrinker);
> +error:
> + if (pool->acomp_ctx)
> + free_percpu(pool->acomp_ctx);
> + while (i--)
> + zpool_destroy_pool(pool->zpools[i]);
> + kfree(pool);
> + return NULL;
> +}
> +
> +static struct zswap_pool *__zswap_pool_create_fallback(void)
> +{
> + bool has_comp, has_zpool;
> +
> + has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
> + if (!has_comp && strcmp(zswap_compressor,
> + CONFIG_ZSWAP_COMPRESSOR_DEFAULT)) {
> + pr_err("compressor %s not available, using default %s\n",
> + zswap_compressor, CONFIG_ZSWAP_COMPRESSOR_DEFAULT);
> + param_free_charp(&zswap_compressor);
> + zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
> + has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
> + }
> + if (!has_comp) {
> + pr_err("default compressor %s not available\n",
> + zswap_compressor);
> + param_free_charp(&zswap_compressor);
> + zswap_compressor = ZSWAP_PARAM_UNSET;
> + }
> +
> + has_zpool = zpool_has_pool(zswap_zpool_type);
> + if (!has_zpool && strcmp(zswap_zpool_type,
> + CONFIG_ZSWAP_ZPOOL_DEFAULT)) {
> + pr_err("zpool %s not available, using default %s\n",
> + zswap_zpool_type, CONFIG_ZSWAP_ZPOOL_DEFAULT);
> + param_free_charp(&zswap_zpool_type);
> + zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
> + has_zpool = zpool_has_pool(zswap_zpool_type);
> + }
> + if (!has_zpool) {
> + pr_err("default zpool %s not available\n",
> + zswap_zpool_type);
> + param_free_charp(&zswap_zpool_type);
> + zswap_zpool_type = ZSWAP_PARAM_UNSET;
> + }
> +
> + if (!has_comp || !has_zpool)
> + return NULL;
> +
> + return zswap_pool_create(zswap_zpool_type, zswap_compressor);
> +}
> +
> +static void zswap_pool_destroy(struct zswap_pool *pool)
> +{
> + int i;
> +
> + zswap_pool_debug("destroying", pool);
> +
> + shrinker_free(pool->shrinker);
> + cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
> + free_percpu(pool->acomp_ctx);
> + list_lru_destroy(&pool->list_lru);
> +
> + spin_lock(&zswap_pools_lock);
> + mem_cgroup_iter_break(NULL, pool->next_shrink);
> + pool->next_shrink = NULL;
> + spin_unlock(&zswap_pools_lock);
> +
> + for (i = 0; i < ZSWAP_NR_ZPOOLS; i++)
> + zpool_destroy_pool(pool->zpools[i]);
> + kfree(pool);
> +}
> +
> /* should be called under RCU */
> #ifdef CONFIG_MEMCG
> static inline struct mem_cgroup *mem_cgroup_from_entry(struct zswap_entry *entry)
> @@ -970,151 +1122,6 @@ static void shrink_worker(struct work_struct *w)
> zswap_pool_put(pool);
> }
>
> -static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
> -{
> - int i;
> - struct zswap_pool *pool;
> - char name[38]; /* 'zswap' + 32 char (max) num + \0 */
> - gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
> - int ret;
> -
> - if (!zswap_has_pool) {
> - /* if either are unset, pool initialization failed, and we
> - * need both params to be set correctly before trying to
> - * create a pool.
> - */
> - if (!strcmp(type, ZSWAP_PARAM_UNSET))
> - return NULL;
> - if (!strcmp(compressor, ZSWAP_PARAM_UNSET))
> - return NULL;
> - }
> -
> - pool = kzalloc(sizeof(*pool), GFP_KERNEL);
> - if (!pool)
> - return NULL;
> -
> - for (i = 0; i < ZSWAP_NR_ZPOOLS; i++) {
> - /* unique name for each pool specifically required by zsmalloc */
> - snprintf(name, 38, "zswap%x",
> - atomic_inc_return(&zswap_pools_count));
> -
> - pool->zpools[i] = zpool_create_pool(type, name, gfp);
> - if (!pool->zpools[i]) {
> - pr_err("%s zpool not available\n", type);
> - goto error;
> - }
> - }
> - pr_debug("using %s zpool\n", zpool_get_type(pool->zpools[0]));
> -
> - strscpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
> -
> - pool->acomp_ctx = alloc_percpu(*pool->acomp_ctx);
> - if (!pool->acomp_ctx) {
> - pr_err("percpu alloc failed\n");
> - goto error;
> - }
> -
> - ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE,
> - &pool->node);
> - if (ret)
> - goto error;
> -
> - zswap_alloc_shrinker(pool);
> - if (!pool->shrinker)
> - goto error;
> -
> - pr_debug("using %s compressor\n", pool->tfm_name);
> -
> - /* being the current pool takes 1 ref; this func expects the
> - * caller to always add the new pool as the current pool
> - */
> - kref_init(&pool->kref);
> - INIT_LIST_HEAD(&pool->list);
> - if (list_lru_init_memcg(&pool->list_lru, pool->shrinker))
> - goto lru_fail;
> - shrinker_register(pool->shrinker);
> - INIT_WORK(&pool->shrink_work, shrink_worker);
> - atomic_set(&pool->nr_stored, 0);
> -
> - zswap_pool_debug("created", pool);
> -
> - return pool;
> -
> -lru_fail:
> - list_lru_destroy(&pool->list_lru);
> - shrinker_free(pool->shrinker);
> -error:
> - if (pool->acomp_ctx)
> - free_percpu(pool->acomp_ctx);
> - while (i--)
> - zpool_destroy_pool(pool->zpools[i]);
> - kfree(pool);
> - return NULL;
> -}
> -
> -static struct zswap_pool *__zswap_pool_create_fallback(void)
> -{
> - bool has_comp, has_zpool;
> -
> - has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
> - if (!has_comp && strcmp(zswap_compressor,
> - CONFIG_ZSWAP_COMPRESSOR_DEFAULT)) {
> - pr_err("compressor %s not available, using default %s\n",
> - zswap_compressor, CONFIG_ZSWAP_COMPRESSOR_DEFAULT);
> - param_free_charp(&zswap_compressor);
> - zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
> - has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
> - }
> - if (!has_comp) {
> - pr_err("default compressor %s not available\n",
> - zswap_compressor);
> - param_free_charp(&zswap_compressor);
> - zswap_compressor = ZSWAP_PARAM_UNSET;
> - }
> -
> - has_zpool = zpool_has_pool(zswap_zpool_type);
> - if (!has_zpool && strcmp(zswap_zpool_type,
> - CONFIG_ZSWAP_ZPOOL_DEFAULT)) {
> - pr_err("zpool %s not available, using default %s\n",
> - zswap_zpool_type, CONFIG_ZSWAP_ZPOOL_DEFAULT);
> - param_free_charp(&zswap_zpool_type);
> - zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
> - has_zpool = zpool_has_pool(zswap_zpool_type);
> - }
> - if (!has_zpool) {
> - pr_err("default zpool %s not available\n",
> - zswap_zpool_type);
> - param_free_charp(&zswap_zpool_type);
> - zswap_zpool_type = ZSWAP_PARAM_UNSET;
> - }
> -
> - if (!has_comp || !has_zpool)
> - return NULL;
> -
> - return zswap_pool_create(zswap_zpool_type, zswap_compressor);
> -}
> -
> -static void zswap_pool_destroy(struct zswap_pool *pool)
> -{
> - int i;
> -
> - zswap_pool_debug("destroying", pool);
> -
> - shrinker_free(pool->shrinker);
> - cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
> - free_percpu(pool->acomp_ctx);
> - list_lru_destroy(&pool->list_lru);
> -
> - spin_lock(&zswap_pools_lock);
> - mem_cgroup_iter_break(NULL, pool->next_shrink);
> - pool->next_shrink = NULL;
> - spin_unlock(&zswap_pools_lock);
> -
> - for (i = 0; i < ZSWAP_NR_ZPOOLS; i++)
> - zpool_destroy_pool(pool->zpools[i]);
> - kfree(pool);
> -}
> -
> static int __must_check zswap_pool_get(struct zswap_pool *pool)
> {
> if (!pool)
> --
> 2.43.0
>

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Previous message: Borislav Petkov: "Re: [patch v5 06/19] x86/cpu: Provide a sane leaf 0xb/0x1f parser"
In reply to: Johannes Weiner: "[PATCH 10/20] mm: zswap: function ordering: pool alloc & free"
Next in thread: Johannes Weiner: "[PATCH 11/20] mm: zswap: function ordering: pool refcounting"
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