MDEV-37250 buf_pool_t::shrink() assertion failure

buf_pool_t::shrink(): When relocating a dirty page of the temporary
tablespace, reset the oldest_modification() on the discarded block,
like we do for persistent pages in buf_flush_relocate_on_flush_list().

buf_pool_t::resize(): Add debug assertions to catch this error earlier.

This bug does not seem to affect non-debug builds.

Reviewed by: Thirunarayanan Balathandayuthapani

Author: dr-m

mysql-test/suite/innodb/r/innodb_buffer_pool_shrink_temporary.result

@@ -0,0 +1,17 @@
+call mtr.add_suppression("innodb_buffer_pool_size change aborted");
+SET @b=REPEAT('0',1048576);
+CREATE TEMPORARY TABLE t (c MEDIUMTEXT) ENGINE=InnoDB;
+INSERT INTO t VALUES
+(@b),(@b),(@b),(@b),(@b),(@b),(@b),(@b),(@b),(@b),(@b);
+SET STATEMENT max_statement_time=0.000001 FOR
+SET GLOBAL innodb_buffer_pool_size=6291456;
+SET STATEMENT max_statement_time=0.000001 FOR
+SET GLOBAL innodb_buffer_pool_size=6291456;
+SET STATEMENT max_statement_time=0.000001 FOR
+SET GLOBAL innodb_buffer_pool_size=6291456;
+SET GLOBAL innodb_buffer_pool_size=6291456;
+SET GLOBAL innodb_buffer_pool_size=16777216;
+CHECKSUM TABLE t;
+Table	Checksum
+test.t	4050893687
+DROP TEMPORARY TABLE t;

mysql-test/suite/innodb/t/innodb_buffer_pool_shrink_temporary.opt

@@ -0,0 +1 @@
+--innodb-buffer-pool-size=16m

mysql-test/suite/innodb/t/innodb_buffer_pool_shrink_temporary.test

@@ -0,0 +1,20 @@
+--source include/have_innodb.inc
+call mtr.add_suppression("innodb_buffer_pool_size change aborted");
+SET @b=REPEAT('0',1048576);
+CREATE TEMPORARY TABLE t (c MEDIUMTEXT) ENGINE=InnoDB;
+INSERT INTO t VALUES
+(@b),(@b),(@b),(@b),(@b),(@b),(@b),(@b),(@b),(@b),(@b);
+--error 0,ER_WRONG_USAGE
+SET STATEMENT max_statement_time=0.000001 FOR
+SET GLOBAL innodb_buffer_pool_size=6291456;
+--error 0,ER_WRONG_USAGE
+SET STATEMENT max_statement_time=0.000001 FOR
+SET GLOBAL innodb_buffer_pool_size=6291456;
+--error 0,ER_WRONG_USAGE
+SET STATEMENT max_statement_time=0.000001 FOR
+SET GLOBAL innodb_buffer_pool_size=6291456;
+--error 0,ER_WRONG_USAGE
+SET GLOBAL innodb_buffer_pool_size=6291456;
+SET GLOBAL innodb_buffer_pool_size=16777216;
+CHECKSUM TABLE t;
+DROP TEMPORARY TABLE t;

storage/innobase/buf/buf0buf.cc

@@ -1760,6 +1760,11 @@ ATTRIBUTE_COLD buf_pool_t::shrink_status buf_pool_t::shrink(size_t size)
         buf_flush_relocate_on_flush_list(b, &block->page);
         mysql_mutex_unlock(&flush_list_mutex);
       }
+      else
+      {
+        ut_d(if (auto om= b->oldest_modification()) ut_ad(om == 2));
+        b->oldest_modification_.store(0, std::memory_order_relaxed);
+      }
     }
 
     /* relocate LRU list */
@@ -2091,10 +2096,11 @@ ATTRIBUTE_COLD void buf_pool_t::resize(size_t size, THD *thd) noexcept
 
     while (buf_page_t *b= UT_LIST_GET_FIRST(withdrawn))
     {
+      ut_ad(!b->oldest_modification());
+      ut_ad(b->state() == buf_page_t::NOT_USED);
       UT_LIST_REMOVE(withdrawn, b);
       UT_LIST_ADD_LAST(free, b);
       ut_d(b->in_free_list= true);
-      ut_ad(b->state() == buf_page_t::NOT_USED);
       b->lock.init();
     }