2017-08-18  9:27:47 140620248848640 [Note] InnoDB: innodb_empty_free_list_algorithm has been changed to legacy because of small buffer pool size. In order to use backoff, increase buffer pool at least up to 20MB.

2017-08-18  9:27:48 140620248848640 [Note] InnoDB: Using mutexes to ref count buffer pool pages
2017-08-18  9:27:48 140620248848640 [Note] InnoDB: The InnoDB memory heap is disabled
2017-08-18  9:27:48 140620248848640 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2017-08-18  9:27:48 140620248848640 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2017-08-18  9:27:48 140620248848640 [Note] InnoDB: Compressed tables use zlib 1.2.8
2017-08-18  9:27:48 140620248848640 [Note] InnoDB: Using Linux native AIO
2017-08-18  9:27:48 140620248848640 [Note] InnoDB: Using SSE crc32 instructions
2017-08-18  9:27:48 140620248848640 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2017-08-18  9:27:48 140620248848640 [Note] InnoDB: Completed initialization of buffer pool
2017-08-18  9:27:48 140620248848640 [Note] InnoDB: Highest supported file format is Barracuda.
2017-08-18  9:27:48 140620248848640 [Note] InnoDB: 128 rollback segment(s) are active.
2017-08-18  9:27:48 140620248848640 [Note] InnoDB: Waiting for purge to start
2017-08-18  9:27:48 140620248848640 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.36-82.1 started; log sequence number 53239971340
2017-08-18  9:27:48 140620248848640 [Note] Plugin 'FEEDBACK' is disabled.
2017-08-18  9:27:48 140619624179456 [Note] InnoDB: Dumping buffer pool(s) not yet started
2017-08-18  9:27:48 140620248848640 [Note] Server socket created on IP: '127.0.0.1'.
2017-08-18  9:27:48 140620248848640 [Note] /usr/sbin/mysqld: ready for connections.
Version: '10.1.26-MariaDB-1~stretch'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  mariadb.org binary distribution
2017-08-18 09:28:52 7fe4afdc9700  InnoDB: Assertion failure in thread 140620179740416 in file row0ins.cc line 284
InnoDB: Failing assertion: *cursor->index->name == TEMP_INDEX_PREFIX
InnoDB: We intentionally generate a memory trap.
InnoDB: Submit a detailed bug report to http://bugs.mysql.com.
InnoDB: If you get repeated assertion failures or crashes, even
InnoDB: immediately after the mysqld startup, there may be
InnoDB: corruption in the InnoDB tablespace. Please refer to
InnoDB: http://dev.mysql.com/doc/refman/5.6/en/forcing-innodb-recovery.html
InnoDB: about forcing recovery.
170818  9:28:52 [ERROR] mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.

To report this bug, see https://mariadb.com/kb/en/reporting-bugs

We will try our best to scrape up some info that will hopefully help
diagnose the problem, but since we have already crashed, 
something is definitely wrong and this may fail.

Server version: 10.1.26-MariaDB-1~stretch
key_buffer_size=16777216
read_buffer_size=131072
max_used_connections=8
max_threads=153
thread_count=1
It is possible that mysqld could use up to 
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 352445 K  bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x7fe48c631008
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = 0x7fe4afdc8cb8 thread_stack 0x30000
/usr/sbin/mysqld(my_print_stacktrace+0x2e)[0x55e187c6385e]
/usr/sbin/mysqld(handle_fatal_signal+0x3bd)[0x55e1877a81cd]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x110c0)[0x7fe4b3c270c0]
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0xcf)[0x7fe4b1e54fcf]
/lib/x86_64-linux-gnu/libc.so.6(abort+0x16a)[0x7fe4b1e563fa]
/usr/sbin/mysqld(+0x8c76f0)[0x55e187ace6f0]
/usr/sbin/mysqld(+0x8c981b)[0x55e187ad081b]
/usr/sbin/mysqld(+0x8c9c0b)[0x55e187ad0c0b]
/usr/sbin/mysqld(+0x8d6672)[0x55e187add672]
/usr/sbin/mysqld(+0x82d615)[0x55e187a34615]
/usr/sbin/mysqld(_ZN7handler12ha_write_rowEPh+0x4c7)[0x55e1877b32d7]
/usr/sbin/mysqld(_Z12write_recordP3THDP5TABLEP12st_copy_info+0x72)[0x55e1875f7042]
/usr/sbin/mysqld(_Z12mysql_insertP3THDP10TABLE_LISTR4ListI4ItemERS3_IS5_ES6_S6_15enum_duplicatesb+0x1206)[0x55e187601446]
/usr/sbin/mysqld(_Z21mysql_execute_commandP3THD+0x4157)[0x55e187616ca7]
/usr/sbin/mysqld(_Z11mysql_parseP3THDPcjP12Parser_state+0x311)[0x55e18761baa1]
/usr/sbin/mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0x27df)[0x55e18761f41f]
/usr/sbin/mysqld(_Z10do_commandP3THD+0x148)[0x55e18761fc38]
/usr/sbin/mysqld(_Z24do_handle_one_connectionP3THD+0x1d2)[0x55e1876edd62]
/usr/sbin/mysqld(handle_one_connection+0x40)[0x55e1876edec0]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x7494)[0x7fe4b3c1d494]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x3f)[0x7fe4b1f0aaff]

Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (0x7fe493bd7020): INSERT INTO cache_menu (cid, serialized, created, expire, data) VALUES ('links:navigation:page:node/462:en:1:0', '1', '1503041332', '0', 'a:4:{s:9:\"min_depth\";i:1;s:9:\"max_depth\";N;s:8:\"expanded\";a:2:{i:0;i:0;i:1149;s:4:\"1149\";}s:12:\"active_trail\";a:2:{i:0;i:0;i:1149;s:4:\"1149\";}}')
Connection ID (thread ID): 38
Status: NOT_KILLED

Optimizer switch: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on,extended_keys=on,exists_to_in=on,orderby_uses_equalities=off

The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains
information that should help you find out what is causing the crash.
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: innodb_empty_free_list_algorithm has been changed to legacy because of small buffer pool size. In order to use backoff, increase buffer pool at least up to 20MB.

2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Using mutexes to ref count buffer pool pages
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: The InnoDB memory heap is disabled
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Compressed tables use zlib 1.2.8
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Using Linux native AIO
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Using SSE crc32 instructions
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Completed initialization of buffer pool
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Highest supported file format is Barracuda.
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Starting crash recovery from checkpoint LSN=53239971350
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Restoring possible half-written data pages from the doublewrite buffer...
InnoDB: 1 transaction(s) which must be rolled back or cleaned up
InnoDB: in total 1 row operations to undo
InnoDB: Trx id counter is 42123520
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Starting final batch to recover 20 pages from redo log
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: 128 rollback segment(s) are active.
2017-08-18  9:28:58 140212704602368 [Note] InnoDB: Waiting for purge to start
2017-08-18  9:28:58 140212143384320 [Note] InnoDB: Starting in background the rollback of recovered transactions
2017-08-18 09:28:58 7f85aeffe700  InnoDB: Rolling back trx with id 42123103, 1 rows to undo
2017-08-18  9:28:58 140212143384320 [Note] InnoDB: Rollback of trx with id 42123103 completed
2017-08-18  9:28:58 140212143384320 [Note] InnoDB: Rollback of non-prepared transactions completed
2017-08-18  9:28:58 140212704602368 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.36-82.1 started; log sequence number 53240150746
2017-08-18  9:28:58 140212704602368 [Note] Plugin 'FEEDBACK' is disabled.
2017-08-18  9:28:58 140212704602368 [Note] Recovering after a crash using tc.log
2017-08-18  9:28:58 140212704602368 [Note] Starting crash recovery...
2017-08-18  9:28:58 140212704602368 [Note] Crash recovery finished.
2017-08-18  9:28:58 140212076242688 [Note] InnoDB: Dumping buffer pool(s) not yet started
2017-08-18  9:28:58 140212704602368 [Note] Server socket created on IP: '127.0.0.1'.
2017-08-18  9:28:58 140212704602368 [Note] /usr/sbin/mysqld: ready for connections.
Version: '10.1.26-MariaDB-1~stretch'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  mariadb.org binary distribution
2017-08-18  9:29:06 140212704007936 [ERROR] mysqld: Table './drupal/users' is marked as crashed and should be repaired
2017-08-18  9:29:06 140212704007936 [Warning] Checking table:   './drupal/users'
2017-08-18  9:29:06 140212704007936 [ERROR] mysqld: Table './drupal/sessions' is marked as crashed and should be repaired
2017-08-18  9:29:06 140212704007936 [Warning] Checking table:   './drupal/sessions'
2017-08-18  9:29:06 140212704007936 [ERROR] mysqld: Table './drupal/node_counter' is marked as crashed and should be repaired
2017-08-18  9:29:06 140212704007936 [Warning] Checking table:   './drupal/node_counter'
2017-08-18  9:29:06 140212704007936 [ERROR] mysqld: Table './drupal/history' is marked as crashed and should be repaired
2017-08-18  9:29:06 140212704007936 [Warning] Checking table:   './drupal/history'
2017-08-18  9:29:06 140212704007936 [ERROR] mysqld: Table './drupal/cache_views' is marked as crashed and should be repaired