target/linux/bcm27xx/patches-5.15/950-0235-zswap-Defer-zswap-initialisation.patch

   1 From 42487c7c83a14fd00b69038932baf6373d422b59 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.com>
   3 Date: Tue, 5 May 2020 15:23:32 +0100
   4 Subject: [PATCH] zswap: Defer zswap initialisation
   5
   6 Enabling zswap support in the kernel configuration costs about 1.5MB
   7 of RAM, even when zswap is not enabled at runtime. This cost can be
   8 reduced significantly by deferring initialisation (including pool
   9 creation) until the "enabled" parameter is set to true. There is a
  10 small cost to this in that some initialisation code has to remain in
  11 memory after the init phase, just in case they are needed later,
  12 but the total size increase is negligible.
  13
  14 See: https://github.com/raspberrypi/linux/pull/3432
  15
  16 Signed-off-by: Phil Elwell <phil@raspberrypi.com>
  17 ---
  18  mm/zswap.c | 53 +++++++++++++++++++++++++++++------------------------
  19  1 file changed, 29 insertions(+), 24 deletions(-)
  20
  21 --- a/mm/zswap.c
  22 +++ b/mm/zswap.c
  23 @@ -648,8 +648,9 @@ error:
  24         return NULL;
  25  }
  26
  27 -static __init struct zswap_pool *__zswap_pool_create_fallback(void)
  28 +static bool zswap_try_pool_create(void)
  29  {
  30 +       struct zswap_pool *pool;
  31         bool has_comp, has_zpool;
  32
  33         has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
  34 @@ -685,9 +686,21 @@ static __init struct zswap_pool *__zswap
  35         }
  36
  37         if (!has_comp || !has_zpool)
  38 -               return NULL;
  39 +               return false;
  40 +
  41 +       pool = zswap_pool_create(zswap_zpool_type, zswap_compressor);
  42
  43 -       return zswap_pool_create(zswap_zpool_type, zswap_compressor);
  44 +       if (pool) {
  45 +               pr_info("loaded using pool %s/%s\n", pool->tfm_name,
  46 +                       zpool_get_type(pool->zpool));
  47 +               list_add(&pool->list, &zswap_pools);
  48 +               zswap_has_pool = true;
  49 +       } else {
  50 +               pr_err("pool creation failed\n");
  51 +               zswap_enabled = false;
  52 +       }
  53 +
  54 +       return zswap_enabled;
  55  }
  56
  57  static void zswap_pool_destroy(struct zswap_pool *pool)
  58 @@ -860,16 +873,19 @@ static int zswap_zpool_param_set(const c
  59  static int zswap_enabled_param_set(const char *val,
  60                                    const struct kernel_param *kp)
  61  {
  62 +       int ret;
  63 +
  64         if (zswap_init_failed) {
  65                 pr_err("can't enable, initialization failed\n");
  66                 return -ENODEV;
  67         }
  68 -       if (!zswap_has_pool && zswap_init_started) {
  69 -               pr_err("can't enable, no pool configured\n");
  70 -               return -ENODEV;
  71 -       }
  72
  73 -       return param_set_bool(val, kp);
  74 +       ret = param_set_bool(val, kp);
  75 +       if (!ret && zswap_enabled && zswap_init_started && !zswap_has_pool)
  76 +               if (!zswap_try_pool_create())
  77 +                       ret = -ENODEV;
  78 +
  79 +       return ret;
  80  }
  81
  82  /*********************************
  83 @@ -1436,7 +1452,6 @@ static int __init zswap_debugfs_init(voi
  84  **********************************/
  85  static int __init init_zswap(void)
  86  {
  87 -       struct zswap_pool *pool;
  88         int ret;
  89
  90         zswap_init_started = true;
  91 @@ -1460,29 +1475,19 @@ static int __init init_zswap(void)
  92         if (ret)
  93                 goto hp_fail;
  94
  95 -       pool = __zswap_pool_create_fallback();
  96 -       if (pool) {
  97 -               pr_info("loaded using pool %s/%s\n", pool->tfm_name,
  98 -                       zpool_get_type(pool->zpool));
  99 -               list_add(&pool->list, &zswap_pools);
 100 -               zswap_has_pool = true;
 101 -       } else {
 102 -               pr_err("pool creation failed\n");
 103 -               zswap_enabled = false;
 104 -       }
 105 -
 106         shrink_wq = create_workqueue("zswap-shrink");
 107         if (!shrink_wq)
 108 -               goto fallback_fail;
 109 +               goto hp_fail;
 110
 111         frontswap_register_ops(&zswap_frontswap_ops);
 112         if (zswap_debugfs_init())
 113                 pr_warn("debugfs initialization failed\n");
 114 +
 115 +       if (zswap_enabled)
 116 +               zswap_try_pool_create();
 117 +
 118         return 0;
 119
 120 -fallback_fail:
 121 -       if (pool)
 122 -               zswap_pool_destroy(pool);
 123  hp_fail:
 124         cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
 125  dstmem_fail: