The problem was observed on the following MariaDB trees

10.2 c1caada886270567bfc9d4f57f5ea40d31dd56ea 2018-12-13

10.3 f6e16bdc62d80a1b26a955aafb1b60fafa912beb 2018-12-13

10.4 67e3d1ee93505e320bdb4343a8a8be827183a58e 2018-12-14

Compile from source with debug

./mysql-test-run.pl bug_aria3 

============================================

TEST                                      RESULT   TIME (ms) or COMMENT

--------------------------------------------------------------------------

worker[1] Using MTR_BUILD_THREAD 300, with reserved ports 16000..16019

main.bug_aria3                           [ fail ]

        Test ended at 2018-12-14 12:08:52

CURRENT_TEST: main.bug_aria3

...

Version: '10.2.20-MariaDB-debug-log'  socket: ...

mysqld: /home/mleich/Server/10.2/storage/maria/ma_bitmap.c:3108: flush_log_for_bitmap: Assertion `share->now_transactional' failed.

181214 12:08:52 [ERROR] mysqld got signal 6 ;

...

Query (0x7ff26c010780): CHECK TABLE t1

Connection ID (thread ID): 6

Status: NOT_KILLED

#3  <signal handler called>

#4  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51

#5  0x00007ff294a38f5d in __GI_abort () at abort.c:90

#6  0x00007ff294a2ef17 in __assert_fail_base (fmt=<optimized out>, assertion=assertion@entry=0x558a964dc82b "share->now_transactional", file=file@entry=0x558a964dbc60 "storage/maria/ma_bitmap.c", line=line@entry=3108, function=function@entry=0x558a964dcb80 <__PRETTY_FUNCTION__.16870> "flush_log_for_bitmap") at assert.c:92

#7  0x00007ff294a2efc2 in __GI___assert_fail (assertion=0x558a964dc82b "share->now_transactional", file=0x558a964dbc60 "storage/maria/ma_bitmap.c", line=3108, function=0x558a964dcb80 <__PRETTY_FUNCTION__.16870> "flush_log_for_bitmap") at assert.c:101

#8  0x0000558a96034945 in flush_log_for_bitmap (args=0x7ff28ac67ad0) at storage/maria/ma_bitmap.c:3108

#9  0x0000558a95fe2ca4 in pagecache_fwrite (pagecache=0x558a975dd720 <maria_pagecache_var>, filedesc=0x7ff28b82a490, buffer=0x7ff28b861018 "\001", pageno=0, type=PAGECACHE_PLAIN_PAGE, flags=36) at storage/maria/ma_pagecache.c:660

#10 0x0000558a95fec630 in flush_cached_blocks (pagecache=0x558a975dd720 <maria_pagecache_var>, file=0x7ff26c019280, cache=0x7ff28ac67ca0, end=0x7ff28ac67cb0, type=FLUSH_FORCE_WRITE, first_errno=0x7ff28ac67c04) at storage/maria/ma_pagecache.c:4420

#11 0x0000558a95fecfe7 in flush_pagecache_blocks_int (pagecache=0x558a975dd720 <maria_pagecache_var>, file=0x7ff26c019280, type=FLUSH_FORCE_WRITE, filter=0x0, filter_arg=0x0) at storage/maria/ma_pagecache.c:4716

#12 0x0000558a95fed408 in flush_pagecache_blocks_with_filter (pagecache=0x558a975dd720 <maria_pagecache_var>, file=0x7ff26c019280, type=FLUSH_FORCE_WRITE, filter=0x0, filter_arg=0x0) at storage/maria/ma_pagecache.c:4833

#13 0x0000558a960082cd in _ma_flush_table_files (info=0x7ff26c018e48, flush_data_or_index=3, flush_type_for_data=FLUSH_FORCE_WRITE, flush_type_for_index=FLUSH_FORCE_WRITE) at storage/maria/ma_extra.c:643

#14 0x0000558a9604888f in maria_chk_size (param=0x7ff26c01f000, info=0x7ff26c018e48) at storage/maria/ma_check.c:418

#15 0x0000558a95fbfc86 in ha_maria::check (this=0x7ff26c018750, thd=0x7ff26c000ce8, check_opt=0x7ff26c0057d8) at storage/maria/ha_maria.cc:1339

#16 0x0000558a95a1f0db in handler::ha_check (this=0x7ff26c018750, thd=0x7ff26c000ce8, check_opt=0x7ff26c0057d8) at sql/handler.cc:3974

#17 0x0000558a958fbac6 in mysql_admin_table (thd=0x7ff26c000ce8, tables=0x7ff26c010848, check_opt=0x7ff26c0057d8, operator_name=0x558a9629c23c "check", lock_type=TL_READ_NO_INSERT, org_open_for_modify=false, repair_table_use_frm=false, extra_open_options=32, prepare_func=0x0, operator_func=(int (handler::*)(handler * const, THD *, HA_CHECK_OPT *)) 0x558a95a1efb6 <handler::ha_check(THD*, st_ha_check_opt*)>, view_operator_func=0x558a958971fe <view_check(THD*, TABLE_LIST*, st_ha_check_opt*)>) at sql/sql_admin.cc:798

#18 0x0000558a958fdc4b in Sql_cmd_check_table::execute (this=0x7ff26c010e60, thd=0x7ff26c000ce8) at sql/sql_admin.cc:1342 

#19 0x0000558a957a72a0 in mysql_execute_command (thd=0x7ff26c000ce8) at sql/sql_parse.cc:6227

#20 0x0000558a957ac3ec in mysql_parse (thd=0x7ff26c000ce8, rawbuf=0x7ff26c010780 "CHECK TABLE t1", length=14, parser_state=0x7ff28ac6d1f0, is_com_multi=false, is_next_command=false) at sql/sql_parse.cc:8014

#21 0x0000558a95799a6d in dispatch_command (command=COM_QUERY, thd=0x7ff26c000ce8, packet=0x7ff26c008469 "", packet_length=15, is_com_multi=false, is_next_command=false) at sql/sql_parse.cc:1824

#22 0x0000558a9579840b in do_command (thd=0x7ff26c000ce8) at sql/sql_parse.cc:1378

#23 0x0000558a958e977f in do_handle_one_connection (connect=0x558a980719d8) at sql/sql_connect.cc:1335

#24 0x0000558a958e94ff in handle_one_connection (arg=0x558a980719d8) at sql/sql_connect.cc:1241

The problem was found during RQG testing.

There it shows quite frequent up in case tables using Aria get exposed to a DDL/DML mix.