MDEV-27467: innodb to enforce the minimum innodb_buffer_pool_size in SET GLOBAL

.. to be the same as startup.

In resolving MDEV-27461, BUF_LRU_MIN_LEN (256) is the minimum number of
pages for the innodb buffer pool size. Obviously we need more than just
flushing pages. Taking the 16k page size and its default minimum, an
extra 25% is needed on top of the flushing pages to make a workable buffer
pool.

The minimum innodb_buffer_pool_chunk_size (1M) restricts the minimum
otherwise we'd have a pool made up of different chunk sizes.

The resulting minimum innodb buffer pool sizes are:

Page Size, Previously minimum (startup), with change.
        4k                            5M           2M
        8k                            5M           3M
       16k                            5M           5M
       32k                           24M          10M
       64k                           24M          20M

With this patch, SET GLOBAL innodb_buffer_pool_size minimums are
enforced.

The evident minimum system variable size for innodb_buffer_pool_size
is 2M, however this is only setable if using 4k page size. As
the order of the page_size and buffer_pool_size aren't fixed, we can't
hide this change.

Subsequent changes:
* innodb_buffer_pool_resize_with_chunks.test - raised of pool resize due to new
  minimums. Chunk size also needed increase as the test was for
  pool_size < chunk_size to generate a warning.
* Removed srv_buf_pool_min_size and replaced use with MYSQL_SYSVAR_NAME(buffer_pool_size).min_val
* Removed srv_buf_pool_def_size and replaced constant defination in
  MYSQL_SYSVAR_LONGLONG(buffer_pool_size)
* Reordered ha_innodb to allow for direct use of MYSQL_SYSVAR_NAME(buffer_pool_size).min_val
* Moved buf_pool_size_align into ha_innodb to access to MYSQL_SYSVAR_NAME(buffer_pool_size).min_val
* loose-innodb_disable_resize_buffer_pool_debug is needed in the
  innodb.restart.opt test so that under debug mode, resizing of the
  innodb buffer pool can occur.

18 files changed, 220 insertions, 76 deletions

diff --git a/mysql-test/suite/innodb/r/innodb_buffer_pool_resize_with_chunks.result b/mysql-test/suite/innodb/r/innodb_buffer_pool_resize_with_chunks.result
index 4bf244c9588..efb652091bf 100644
--- a/mysql-test/suite/innodb/r/innodb_buffer_pool_resize_with_chunks.result
+++ b/mysql-test/suite/innodb/r/innodb_buffer_pool_resize_with_chunks.result
@@ -1,6 +1,6 @@
 select @@innodb_buffer_pool_chunk_size;
 @@innodb_buffer_pool_chunk_size
-2097152
+4194304
 create table t1 (id int not null, val int not null default '0', primary key (id)) ENGINE=InnoDB ROW_FORMAT=COMPRESSED;
 create or replace view view0 as select 1 union all select 1;
 set @`v_id` := 0;
@@ -18,9 +18,9 @@ count(val)
 262144
 drop table t1;
 drop view view0;
-set global innodb_buffer_pool_size = 1048576;
+set global innodb_buffer_pool_size = 2*1048576;
 Warnings:
-Warning	1292	Truncated incorrect innodb_buffer_pool_size value: '1048576'
+Warning	1292	Truncated incorrect innodb_buffer_pool_size value: '2097152'
 select @@innodb_buffer_pool_size;
 @@innodb_buffer_pool_size
-6291456
+4194304
diff --git a/mysql-test/suite/innodb/r/restart,16k,innodb.rdiff b/mysql-test/suite/innodb/r/restart,16k,innodb.rdiff
new file mode 100644
index 00000000000..b36ed067913
--- /dev/null
+++ b/mysql-test/suite/innodb/r/restart,16k,innodb.rdiff
@@ -0,0 +1,16 @@
+--- ./suite/innodb/r/restart.result	2022-01-18 20:36:56.054653376 +1100
++++ suite/innodb/r/restart.reject	2022-01-19 08:12:28.602794678 +1100
+@@ -32,10 +32,10 @@
+ SELECT @@innodb_buffer_pool_size INTO @innodb_buffer_pool_size_orig;
+ SELECT CEILING((256 + 64) * @@innodb_page_size / 1048576) * 1048576 INTO @min_pool_size;
+ EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size -1);
+-ERROR 42000: Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
++ERROR 42000: Variable 'innodb_buffer_pool_size' can't be set to the value of '5242879'
+ SHOW WARNINGS;
+ Level	Code	Message
+-Warning	1210	innodb_buffer_pool_size must be at least MIN_VAL for innodb_page_size=PAGE_SIZE
+-Error	1231	Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
++Warning	1210	innodb_buffer_pool_size must be at least 5242880 for innodb_page_size=16384
++Error	1231	Variable 'innodb_buffer_pool_size' can't be set to the value of '5242879'
+ EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size);
+ SET GLOBAL innodb_buffer_pool_size = @innodb_buffer_pool_size_orig;
diff --git a/mysql-test/suite/innodb/r/restart,32k,innodb.rdiff b/mysql-test/suite/innodb/r/restart,32k,innodb.rdiff
new file mode 100644
index 00000000000..8fa057814c4
--- /dev/null
+++ b/mysql-test/suite/innodb/r/restart,32k,innodb.rdiff
@@ -0,0 +1,16 @@
+--- ./suite/innodb/r/restart.result	2022-01-18 20:36:56.054653376 +1100
++++ suite/innodb/r/restart.reject	2022-01-19 08:07:57.402230887 +1100
+@@ -32,10 +32,10 @@
+ SELECT @@innodb_buffer_pool_size INTO @innodb_buffer_pool_size_orig;
+ SELECT CEILING((256 + 64) * @@innodb_page_size / 1048576) * 1048576 INTO @min_pool_size;
+ EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size -1);
+-ERROR 42000: Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
++ERROR 42000: Variable 'innodb_buffer_pool_size' can't be set to the value of '10485759'
+ SHOW WARNINGS;
+ Level	Code	Message
+-Warning	1210	innodb_buffer_pool_size must be at least MIN_VAL for innodb_page_size=PAGE_SIZE
+-Error	1231	Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
++Warning	1210	innodb_buffer_pool_size must be at least 10485760 for innodb_page_size=32768
++Error	1231	Variable 'innodb_buffer_pool_size' can't be set to the value of '10485759'
+ EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size);
+ SET GLOBAL innodb_buffer_pool_size = @innodb_buffer_pool_size_orig;
diff --git a/mysql-test/suite/innodb/r/restart,4k,innodb.rdiff b/mysql-test/suite/innodb/r/restart,4k,innodb.rdiff
new file mode 100644
index 00000000000..7d0846360e0
--- /dev/null
+++ b/mysql-test/suite/innodb/r/restart,4k,innodb.rdiff
@@ -0,0 +1,16 @@
+--- ./suite/innodb/r/restart.result	2022-01-18 20:36:56.054653376 +1100
++++ suite/innodb/r/restart.reject	2022-01-19 08:13:56.397475513 +1100
+@@ -32,10 +32,10 @@
+ SELECT @@innodb_buffer_pool_size INTO @innodb_buffer_pool_size_orig;
+ SELECT CEILING((256 + 64) * @@innodb_page_size / 1048576) * 1048576 INTO @min_pool_size;
+ EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size -1);
+-ERROR 42000: Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
++ERROR 42000: Variable 'innodb_buffer_pool_size' can't be set to the value of '2097151'
+ SHOW WARNINGS;
+ Level	Code	Message
+-Warning	1210	innodb_buffer_pool_size must be at least MIN_VAL for innodb_page_size=PAGE_SIZE
+-Error	1231	Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
++Warning	1210	innodb_buffer_pool_size must be at least 2097152 for innodb_page_size=4096
++Error	1231	Variable 'innodb_buffer_pool_size' can't be set to the value of '2097151'
+ EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size);
+ SET GLOBAL innodb_buffer_pool_size = @innodb_buffer_pool_size_orig;
diff --git a/mysql-test/suite/innodb/r/restart,64k,innodb.rdiff b/mysql-test/suite/innodb/r/restart,64k,innodb.rdiff
new file mode 100644
index 00000000000..3ac9f45b196
--- /dev/null
+++ b/mysql-test/suite/innodb/r/restart,64k,innodb.rdiff
@@ -0,0 +1,16 @@
+--- ./suite/innodb/r/restart.result	2022-01-18 20:36:56.054653376 +1100
++++ suite/innodb/r/restart.reject	2022-01-19 08:11:32.418759095 +1100
+@@ -32,10 +32,10 @@
+ SELECT @@innodb_buffer_pool_size INTO @innodb_buffer_pool_size_orig;
+ SELECT CEILING((256 + 64) * @@innodb_page_size / 1048576) * 1048576 INTO @min_pool_size;
+ EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size -1);
+-ERROR 42000: Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
++ERROR 42000: Variable 'innodb_buffer_pool_size' can't be set to the value of '20971519'
+ SHOW WARNINGS;
+ Level	Code	Message
+-Warning	1210	innodb_buffer_pool_size must be at least MIN_VAL for innodb_page_size=PAGE_SIZE
+-Error	1231	Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
++Warning	1210	innodb_buffer_pool_size must be at least 20971520 for innodb_page_size=65536
++Error	1231	Variable 'innodb_buffer_pool_size' can't be set to the value of '20971519'
+ EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size);
+ SET GLOBAL innodb_buffer_pool_size = @innodb_buffer_pool_size_orig;
diff --git a/mysql-test/suite/innodb/r/restart,8k,innodb.rdiff b/mysql-test/suite/innodb/r/restart,8k,innodb.rdiff
new file mode 100644
index 00000000000..4da55ebfcef
--- /dev/null
+++ b/mysql-test/suite/innodb/r/restart,8k,innodb.rdiff
@@ -0,0 +1,16 @@
+--- ./suite/innodb/r/restart.result	2022-01-18 20:36:56.054653376 +1100
++++ suite/innodb/r/restart.reject	2022-01-19 08:13:11.027788852 +1100
+@@ -32,10 +32,10 @@
+ SELECT @@innodb_buffer_pool_size INTO @innodb_buffer_pool_size_orig;
+ SELECT CEILING((256 + 64) * @@innodb_page_size / 1048576) * 1048576 INTO @min_pool_size;
+ EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size -1);
+-ERROR 42000: Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
++ERROR 42000: Variable 'innodb_buffer_pool_size' can't be set to the value of '3145727'
+ SHOW WARNINGS;
+ Level	Code	Message
+-Warning	1210	innodb_buffer_pool_size must be at least MIN_VAL for innodb_page_size=PAGE_SIZE
+-Error	1231	Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
++Warning	1210	innodb_buffer_pool_size must be at least 3145728 for innodb_page_size=8192
++Error	1231	Variable 'innodb_buffer_pool_size' can't be set to the value of '3145727'
+ EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size);
+ SET GLOBAL innodb_buffer_pool_size = @innodb_buffer_pool_size_orig;
diff --git a/mysql-test/suite/innodb/r/restart.result b/mysql-test/suite/innodb/r/restart.result
index 5e3315be204..606e94d81db 100644
--- a/mysql-test/suite/innodb/r/restart.result
+++ b/mysql-test/suite/innodb/r/restart.result
@@ -26,3 +26,16 @@ a
 SELECT * FROM td;
 a
 DROP TABLE tr,tc,td;
+#
+# MDEV-27467 innodb to enfore the minimum innodb_buffer_pool_size in SET (resize) the same as startup
+#
+SELECT @@innodb_buffer_pool_size INTO @innodb_buffer_pool_size_orig;
+SELECT CEILING((256 + 64) * @@innodb_page_size / 1048576) * 1048576 INTO @min_pool_size;
+EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size -1);
+ERROR 42000: Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
+SHOW WARNINGS;
+Level	Code	Message
+Warning	1210	innodb_buffer_pool_size must be at least MIN_VAL for innodb_page_size=PAGE_SIZE
+Error	1231	Variable 'innodb_buffer_pool_size' can't be set to the value of 'WRONG_VALUE'
+EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size);
+SET GLOBAL innodb_buffer_pool_size = @innodb_buffer_pool_size_orig;
diff --git a/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_with_chunks.opt b/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_with_chunks.opt
index b97a3995457..ade197de338 100644
--- a/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_with_chunks.opt
+++ b/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_with_chunks.opt
@@ -1,3 +1,3 @@
 --innodb-buffer-pool-size=16M
---innodb-buffer-pool-chunk-size=2M
+--innodb-buffer-pool-chunk-size=4M
 --innodb-page-size=4k
diff --git a/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_with_chunks.test b/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_with_chunks.test
index b04b0306bf1..7a26db65d33 100644
--- a/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_with_chunks.test
+++ b/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_with_chunks.test
@@ -49,7 +49,7 @@ drop table t1;
 drop view view0;
 
 # Try to shrink buffer pool to smaller than chunk size
-set global innodb_buffer_pool_size = 1048576;
+set global innodb_buffer_pool_size = 2*1048576;
 --source include/wait_condition.inc
 select @@innodb_buffer_pool_size;
 
diff --git a/mysql-test/suite/innodb/t/restart.opt b/mysql-test/suite/innodb/t/restart.opt
new file mode 100644
index 00000000000..ce43e89cb2b
--- /dev/null
+++ b/mysql-test/suite/innodb/t/restart.opt
@@ -0,0 +1,2 @@
+--loose-innodb_disable_resize_buffer_pool_debug=0
+--innodb-buffer-pool-chunk-size=1M
diff --git a/mysql-test/suite/innodb/t/restart.test b/mysql-test/suite/innodb/t/restart.test
index d7582306492..3f28b3976c3 100644
--- a/mysql-test/suite/innodb/t/restart.test
+++ b/mysql-test/suite/innodb/t/restart.test
@@ -77,3 +77,26 @@ SELECT * FROM tr;
 SELECT * FROM tc;
 SELECT * FROM td;
 DROP TABLE tr,tc,td;
+
+--echo #
+--echo # MDEV-27467 innodb to enfore the minimum innodb_buffer_pool_size in SET (resize) the same as startup
+--echo #
+
+let $wait_timeout = 180;
+let $wait_condition =
+  SELECT SUBSTR(variable_value, 1, 34) = 'Completed resizing buffer pool at '
+  FROM information_schema.global_status
+  WHERE LOWER(variable_name) = 'innodb_buffer_pool_resize_status';
+
+SELECT @@innodb_buffer_pool_size INTO @innodb_buffer_pool_size_orig;
+SELECT CEILING((256 + 64) * @@innodb_page_size / 1048576) * 1048576 INTO @min_pool_size;
+--error ER_WRONG_VALUE_FOR_VAR
+EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size -1);
+
+SHOW WARNINGS;
+
+EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size);
+
+--source include/wait_condition.inc
+
+SET GLOBAL innodb_buffer_pool_size = @innodb_buffer_pool_size_orig;
diff --git a/mysql-test/suite/sys_vars/r/sysvars_innodb.result b/mysql-test/suite/sys_vars/r/sysvars_innodb.result
index ecc5e9b50bb..a1a59425502 100644
--- a/mysql-test/suite/sys_vars/r/sysvars_innodb.result
+++ b/mysql-test/suite/sys_vars/r/sysvars_innodb.result
@@ -300,7 +300,7 @@ DEFAULT_VALUE	134217728
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	BIGINT
 VARIABLE_COMMENT	The size of the memory buffer InnoDB uses to cache data and indexes of its tables.
-NUMERIC_MIN_VALUE	5242880
+NUMERIC_MIN_VALUE	2097152
 NUMERIC_MAX_VALUE	9223372036854775807
 NUMERIC_BLOCK_SIZE	1048576
 ENUM_VALUE_LIST	NULL
diff --git a/storage/innobase/buf/buf0flu.cc b/storage/innobase/buf/buf0flu.cc
index 26610337d0d..2beddf4b243 100644
--- a/storage/innobase/buf/buf0flu.cc
+++ b/storage/innobase/buf/buf0flu.cc
@@ -191,12 +191,6 @@ static page_cleaner_t	page_cleaner;
 my_bool innodb_page_cleaner_disabled_debug;
 #endif /* UNIV_DEBUG */
 
-/** If LRU list of a buf_pool is less than this size then LRU eviction
-should not happen. This is because when we do LRU flushing we also put
-the blocks on free list. If LRU list is very small then we can end up
-in thrashing. */
-#define BUF_LRU_MIN_LEN		256
-
 /* @} */
 
 /******************************************************************//**
diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index 8fb52b211c6..5d78e64a06b 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -3639,6 +3639,59 @@ static uint innobase_partition_flags()
 	return (0);
 }
 
+/** Return the minimum buffer pool size based on page size */
+static inline ulint min_buffer_pool_size()
+{
+  ulint s= (BUF_LRU_MIN_LEN + BUF_LRU_MIN_LEN / 4) * srv_page_size;
+  /* buf_pool_chunk_size minimum is 1M, so round up to a multiple */
+  ulint alignment= 1U << 20;
+  return UT_CALC_ALIGN(s, alignment);
+}
+
+/** Validate the requested buffer pool size.  Also, reserve the necessary
+memory needed for buffer pool resize.
+@param[in]	thd	thread handle
+@param[in]	var	pointer to system variable
+@param[out]	save	immediate result for update function
+@param[in]	value	incoming string
+@return 0 on success, 1 on failure.
+*/
+static
+int
+innodb_buffer_pool_size_validate(
+	THD*				thd,
+	struct st_mysql_sys_var*	var,
+	void*				save,
+	struct st_mysql_value*		value);
+
+/** Update the system variable innodb_buffer_pool_size using the "saved"
+value. This function is registered as a callback with MySQL.
+@param[in]	thd	thread handle
+@param[in]	var	pointer to system variable
+@param[out]	var_ptr	where the formal string goes
+@param[in]	save	immediate result from check function */
+static
+void
+innodb_buffer_pool_size_update(
+	THD*				thd,
+	struct st_mysql_sys_var*	var,
+	void*				var_ptr,
+	const void*			save);
+
+/* If the default value of innodb_buffer_pool_size is increased to be more than
+BUF_POOL_SIZE_THRESHOLD (srv/srv0start.cc), then srv_buf_pool_instances_default
+can be removed and 8 used instead. The problem with the current setup is that
+with 128MiB default buffer pool size and 8 instances by default we would emit
+a warning when no options are specified. */
+static MYSQL_SYSVAR_LONGLONG(buffer_pool_size, innobase_buffer_pool_size,
+  PLUGIN_VAR_RQCMDARG,
+  "The size of the memory buffer InnoDB uses to cache data and indexes of its tables.",
+  innodb_buffer_pool_size_validate,
+  innodb_buffer_pool_size_update,
+  128LL << 20,
+  2LL << 20,
+  LLONG_MAX, 1024*1024L);
+
 /** Deprecation message about InnoDB file format related parameters */
 #define DEPRECATED_FORMAT_PARAMETER(x)					\
 	"Using " x " is deprecated and the parameter"			\
@@ -3830,12 +3883,15 @@ innobase_init(
 
 	/* The buffer pool needs to be able to accommodate enough many
 	pages, even for larger pages */
-	if (UNIV_PAGE_SIZE > UNIV_PAGE_SIZE_DEF
-	    && innobase_buffer_pool_size < (24 * 1024 * 1024)) {
+	MYSQL_SYSVAR_NAME(buffer_pool_size).min_val= min_buffer_pool_size();
+
+	if (innobase_buffer_pool_size < MYSQL_SYSVAR_NAME(buffer_pool_size).min_val) {
 		ib::error() << "innodb_page_size="
-			<< UNIV_PAGE_SIZE << " requires "
-			<< "innodb_buffer_pool_size > 24M current "
-			<< innobase_buffer_pool_size;
+			<< srv_page_size << " requires "
+			<< "innodb_buffer_pool_size >= "
+			<< (MYSQL_SYSVAR_NAME(buffer_pool_size).min_val >> 20)
+			<< "MiB current " << (innobase_buffer_pool_size >> 20)
+			<< "MiB";
 		goto error;
 	}
 
@@ -20314,36 +20370,6 @@ static MYSQL_SYSVAR_ULONG(autoextend_increment,
   "Data file autoextend increment in megabytes",
   NULL, NULL, 64L, 1L, 1000L, 0);
 
-/** Validate the requested buffer pool size.  Also, reserve the necessary
-memory needed for buffer pool resize.
-@param[in]	thd	thread handle
-@param[in]	var	pointer to system variable
-@param[out]	save	immediate result for update function
-@param[in]	value	incoming string
-@return 0 on success, 1 on failure.
-*/
-static
-int
-innodb_buffer_pool_size_validate(
-	THD*				thd,
-	struct st_mysql_sys_var*	var,
-	void*				save,
-	struct st_mysql_value*		value);
-
-/* If the default value of innodb_buffer_pool_size is increased to be more than
-BUF_POOL_SIZE_THRESHOLD (srv/srv0start.cc), then srv_buf_pool_instances_default
-can be removed and 8 used instead. The problem with the current setup is that
-with 128MiB default buffer pool size and 8 instances by default we would emit
-a warning when no options are specified. */
-static MYSQL_SYSVAR_LONGLONG(buffer_pool_size, innobase_buffer_pool_size,
-  PLUGIN_VAR_RQCMDARG,
-  "The size of the memory buffer InnoDB uses to cache data and indexes of its tables.",
-  innodb_buffer_pool_size_validate,
-  innodb_buffer_pool_size_update,
-  static_cast<longlong>(srv_buf_pool_def_size),
-  static_cast<longlong>(srv_buf_pool_min_size),
-  LLONG_MAX, 1024*1024L);
-
 static MYSQL_SYSVAR_ULONG(buffer_pool_chunk_size, srv_buf_pool_chunk_unit,
   PLUGIN_VAR_RQCMDARG | PLUGIN_VAR_READONLY,
   "Size of a single memory chunk within each buffer pool instance"
@@ -22297,9 +22323,18 @@ innodb_buffer_pool_size_validate(
 {
 	longlong	intbuf;
 
-
 	value->val_int(value, &intbuf);
 
+	if (intbuf < MYSQL_SYSVAR_NAME(buffer_pool_size).min_val) {
+		push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
+				    ER_WRONG_ARGUMENTS,
+				    "innodb_buffer_pool_size must be at least"
+				    " %lld for innodb_page_size=%lu",
+				    MYSQL_SYSVAR_NAME(buffer_pool_size).min_val,
+				    srv_page_size);
+		return(1);
+	}
+
 	if (!srv_was_started) {
 		push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
 				    ER_WRONG_ARGUMENTS,
@@ -22653,3 +22688,21 @@ ib_push_frm_error(
 		break;
 	}
 }
+
+/** Calculate aligned buffer pool size based on srv_buf_pool_chunk_unit,
+if needed.
+@param[in]	size	size in bytes
+@return	aligned size */
+ulint
+buf_pool_size_align(
+	ulint	size)
+{
+  const ib_uint64_t	m = ((ib_uint64_t)srv_buf_pool_instances) * srv_buf_pool_chunk_unit;
+  size = ut_max((size_t) size, (size_t) MYSQL_SYSVAR_NAME(buffer_pool_size).min_val);
+
+  if (size % m == 0) {
+    return(size);
+  } else {
+    return (ulint)((size / m + 1) * m);
+  }
+}
diff --git a/storage/innobase/include/buf0buf.h b/storage/innobase/include/buf0buf.h
index 20281040862..04824293c95 100644
--- a/storage/innobase/include/buf0buf.h
+++ b/storage/innobase/include/buf0buf.h
@@ -95,6 +95,12 @@ struct fil_addr_t;
 #define MAX_PAGE_HASH_LOCKS	1024	/*!< The maximum number of
 					page_hash locks */
 
+/** If LRU list of a buf_pool is less than this size then LRU eviction
+should not happen. This is because when we do LRU flushing we also put
+the blocks on free list. If LRU list is very small then we can end up
+in thrashing. */
+#define BUF_LRU_MIN_LEN		256
+
 extern	buf_pool_t*	buf_pool_ptr;	/*!< The buffer pools
 					of the database */
 
@@ -1373,7 +1379,6 @@ buf_get_nth_chunk_block(
 if needed.
 @param[in]	size	size in bytes
 @return	aligned size */
-UNIV_INLINE
 ulint
 buf_pool_size_align(
 	ulint	size);
diff --git a/storage/innobase/include/buf0buf.inl b/storage/innobase/include/buf0buf.inl
index 49b741ab5c8..488a4c2f585 100644
--- a/storage/innobase/include/buf0buf.inl
+++ b/storage/innobase/include/buf0buf.inl
@@ -1457,22 +1457,3 @@ buf_page_get_frame(
 		return ((buf_block_t*) bpage)->frame;
 	}
 }
-
-/** Calculate aligned buffer pool size based on srv_buf_pool_chunk_unit,
-if needed.
-@param[in]	size	size in bytes
-@return	aligned size */
-UNIV_INLINE
-ulint
-buf_pool_size_align(
-	ulint	size)
-{
-	const ib_uint64_t	m = ((ib_uint64_t)srv_buf_pool_instances) * srv_buf_pool_chunk_unit;
-	size = ut_max(size, srv_buf_pool_min_size);
-
-	if (size % m == 0) {
-		return(size);
-	} else {
-		return (ulint)((size / m + 1) * m);
-	}
-}
diff --git a/storage/innobase/include/srv0srv.h b/storage/innobase/include/srv0srv.h
index 62d7c139ee2..cce90e03b9d 100644
--- a/storage/innobase/include/srv0srv.h
+++ b/storage/innobase/include/srv0srv.h
@@ -389,10 +389,6 @@ extern my_bool	srv_load_corrupted;
 
 /** Requested size in bytes */
 extern ulint		srv_buf_pool_size;
-/** Minimum pool size in bytes */
-extern const ulint	srv_buf_pool_min_size;
-/** Default pool size in bytes */
-extern const ulint	srv_buf_pool_def_size;
 /** Requested buffer pool chunk size. Each buffer pool instance consists
 of one or more chunks. */
 extern ulong		srv_buf_pool_chunk_unit;
diff --git a/storage/innobase/srv/srv0srv.cc b/storage/innobase/srv/srv0srv.cc
index 56c717e142b..f993f5f0f83 100644
--- a/storage/innobase/srv/srv0srv.cc
+++ b/storage/innobase/srv/srv0srv.cc
@@ -244,9 +244,6 @@ UNIV_INTERN os_event_t	srv_allow_writes_event;
 
 /** copy of innodb_buffer_pool_size */
 ulint	srv_buf_pool_size;
-const ulint	srv_buf_pool_min_size	= 5 * 1024 * 1024;
-/** Default pool size in bytes */
-const ulint	srv_buf_pool_def_size	= 128 * 1024 * 1024;
 /** Requested buffer pool chunk size. Each buffer pool instance consists
 of one or more chunks. */
 ulong	srv_buf_pool_chunk_unit;