merged bug#12361113.

Also added tests for partitions key caches.

mysql-test/r/key_cache.result

@@ -383,3 +383,19 @@ Variable_name	Value
 key_cache_block_size	1536
 SET GLOBAL key_cache_block_size= @bug28478_key_cache_block_size;
 DROP TABLE t1;
+#
+# Bug#12361113: crash when load index into cache
+#
+# Note that this creates an empty disabled key cache!
+SET GLOBAL key_cache_none.key_cache_block_size = 1024;
+CREATE TABLE t1 (a INT, b INTEGER NOT NULL, KEY (b) ) ENGINE = MYISAM;
+INSERT INTO t1 VALUES (1, 1);
+CACHE INDEX t1 in key_cache_none;
+ERROR HY000: Unknown key cache 'key_cache_none'
+# The bug crashed the server at LOAD INDEX below. Now it will succeed 
+# since the default cache is used due to CACHE INDEX failed for
+# key_cache_none.
+LOAD INDEX INTO CACHE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	preload_keys	status	OK
+DROP TABLE t1;

mysql-test/r/partition_key_cache.result

@@ -397,6 +397,33 @@ test.t1	assign_to_keycache	error	Subpartition sp0 returned error
 test.t1	assign_to_keycache	Error	Key 'inx_b' doesn't exist in table 't1'
 test.t1	assign_to_keycache	status	Operation failed
 DROP TABLE t1,t2;
+#
+# Bug#12361113: crash when load index into cache
+#
+# Note that this creates an empty disabled key cache!
+SET GLOBAL key_cache_none.key_cache_block_size = 1024;
+CREATE TABLE t1 (a INT, b INTEGER NOT NULL, KEY (b) )
+ENGINE = MYISAM
+PARTITION BY HASH(a) PARTITIONS 2;
+INSERT INTO t1 VALUES (1, 1);
+CACHE INDEX t1 IN key_cache_none;
+ERROR HY000: Unknown key cache 'key_cache_none'
+CACHE INDEX t1 PARTITION (p0) IN key_cache_none;
+ERROR HY000: Unknown key cache 'key_cache_none'
+CACHE INDEX t1 PARTITION (p1) IN key_cache_none;
+ERROR HY000: Unknown key cache 'key_cache_none'
+CACHE INDEX t1 PARTITION (p0) KEY (`b`) IN key_cache_none;
+ERROR HY000: Unknown key cache 'key_cache_none'
+CACHE INDEX t1 PARTITION (p1) KEY (`b`) IN key_cache_none;
+ERROR HY000: Unknown key cache 'key_cache_none'
+# The bug crashed the server at LOAD INDEX below. Now it will succeed
+# since the default cache is used due to CACHE INDEX failed for
+# key_cache_none.
+LOAD INDEX INTO CACHE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	preload_keys	status	OK
+DROP TABLE t1;
+# Clean up
 SET GLOBAL hot_cache.key_buffer_size = 0;
 SET GLOBAL warm_cache.key_buffer_size = 0;
 SET @@global.cold_cache.key_buffer_size = 0;

mysql-test/t/key_cache.test

@@ -251,3 +251,19 @@ SET GLOBAL key_cache_block_size= @bug28478_key_cache_block_size;
 DROP TABLE t1;
 
 # End of 4.1 tests
+
+--echo #
+--echo # Bug#12361113: crash when load index into cache
+--echo #
+
+--echo # Note that this creates an empty disabled key cache!
+SET GLOBAL key_cache_none.key_cache_block_size = 1024;
+CREATE TABLE t1 (a INT, b INTEGER NOT NULL, KEY (b) ) ENGINE = MYISAM;
+INSERT INTO t1 VALUES (1, 1);
+--error ER_UNKNOWN_KEY_CACHE
+CACHE INDEX t1 in key_cache_none;
+--echo # The bug crashed the server at LOAD INDEX below. Now it will succeed 
+--echo # since the default cache is used due to CACHE INDEX failed for
+--echo # key_cache_none.
+LOAD INDEX INTO CACHE t1;
+DROP TABLE t1;

mysql-test/t/partition_key_cache.test

@@ -239,6 +239,34 @@ CACHE INDEX t2 INDEX (`inx_b`) IN hot_cache;
 CACHE INDEX t1 PARTITION (p0) KEY (`inx_b`) IN hot_cache;
 CACHE INDEX t1 INDEX (`inx_b`) IN hot_cache;
 DROP TABLE t1,t2;
+
+--echo #
+--echo # Bug#12361113: crash when load index into cache
+--echo #
+--echo # Note that this creates an empty disabled key cache!
+SET GLOBAL key_cache_none.key_cache_block_size = 1024;
+CREATE TABLE t1 (a INT, b INTEGER NOT NULL, KEY (b) )
+ENGINE = MYISAM
+PARTITION BY HASH(a) PARTITIONS 2;
+INSERT INTO t1 VALUES (1, 1);
+--error ER_UNKNOWN_KEY_CACHE
+CACHE INDEX t1 IN key_cache_none;
+--error ER_UNKNOWN_KEY_CACHE
+CACHE INDEX t1 PARTITION (p0) IN key_cache_none;
+--error ER_UNKNOWN_KEY_CACHE
+CACHE INDEX t1 PARTITION (p1) IN key_cache_none;
+--error ER_UNKNOWN_KEY_CACHE
+CACHE INDEX t1 PARTITION (p0) KEY (`b`) IN key_cache_none;
+--error ER_UNKNOWN_KEY_CACHE
+CACHE INDEX t1 PARTITION (p1) KEY (`b`) IN key_cache_none;
+--echo # The bug crashed the server at LOAD INDEX below. Now it will succeed
+--echo # since the default cache is used due to CACHE INDEX failed for
+--echo # key_cache_none.
+LOAD INDEX INTO CACHE t1;
+DROP TABLE t1;
+
+
+--echo # Clean up
 SET GLOBAL hot_cache.key_buffer_size = 0;
 SET GLOBAL warm_cache.key_buffer_size = 0;
 SET @@global.cold_cache.key_buffer_size = 0;

sql/sql_admin.cc

@@ -911,6 +911,11 @@ bool mysql_assign_to_keycache(THD* thd, TABLE_LIST* tables,
     DBUG_RETURN(TRUE);
   }
   mysql_mutex_unlock(&LOCK_global_system_variables);
+  if (!key_cache->key_cache_inited)
+  {
+    my_error(ER_UNKNOWN_KEY_CACHE, MYF(0), key_cache_name->str);
+    DBUG_RETURN(true);
+  }
   check_opt.key_cache= key_cache;
   DBUG_RETURN(mysql_admin_table(thd, tables, &check_opt,
 				"assign_to_keycache", TL_READ_NO_INSERT, 0, 0,

storage/myisam/mi_preload.c

@@ -53,6 +53,9 @@ int mi_preload(MI_INFO *info, ulonglong key_map, my_bool ignore_leaves)
   if (!keys || !mi_is_any_key_active(key_map) || key_file_length == pos)
     DBUG_RETURN(0);
 
+  /* Preload into a non initialized key cache should never happen. */
+  DBUG_ASSERT(share->key_cache->key_cache_inited);
+
   block_length= keyinfo[0].block_length;
 
   if (ignore_leaves)