150905 18:05:57 [Note] mysqld (mysqld 10.0.21-MariaDB-1~jessie) starting as process 1 ...
150905 18:05:57 [Note] InnoDB: Using mutexes to ref count buffer pool pages
150905 18:05:57 [Note] InnoDB: The InnoDB memory heap is disabled
150905 18:05:57 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
150905 18:05:57 [Note] InnoDB: Memory barrier is not used
150905 18:05:57 [Note] InnoDB: Compressed tables use zlib 1.2.8
150905 18:05:57 [Note] InnoDB: Using Linux native AIO
150905 18:05:57 [Note] InnoDB: Using CPU crc32 instructions
150905 18:05:57 [Note] InnoDB: Initializing buffer pool, size = 256.0M
150905 18:05:57 [Note] InnoDB: Completed initialization of buffer pool
150905 18:05:57 [Note] InnoDB: Highest supported file format is Barracuda.
150905 18:05:57 [Note] InnoDB: 128 rollback segment(s) are active.
150905 18:05:57 [Note] InnoDB: Waiting for purge to start
150905 18:05:58 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.25-73.1 started; log sequence number 1616717
150905 18:05:58 [Note] Plugin 'FEEDBACK' is disabled.
150905 18:05:58 [Note] Server socket created on IP: '::'.
150905 18:05:58 [Warning] 'proxies_priv' entry '@% root@61d2bcf22ebd' ignored in --skip-name-resolve mode.
150905 18:05:58 [Note] Event Scheduler: Loaded 0 events
150905 18:05:58 [Note] mysqld: ready for connections.
Version: '10.0.21-MariaDB-1~jessie'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  mariadb.org binary distribution
150905 18:06:14 [ERROR] mysqld got signal 11 ;
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 http://kb.askmonty.org/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: 10.0.21-MariaDB-1~jessie
key_buffer_size=134217728
read_buffer_size=2097152
max_used_connections=1
max_threads=102
thread_count=1
It is possible that mysqld could use up to 
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 759755 K  bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x0x7fa1d3641008
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 = 0x7fa1f779ce70 thread_stack 0x48000
mysqld(my_print_stacktrace+0x3d)[0x7fa1f7195a2d]
mysqld(handle_fatal_signal+0x31a)[0x7fa1f6cd375a]
/lib/x86_64-linux-gnu/libpthread.so.0(+0xf8d0)[0x7fa1f633d8d0]
mysqld(_ZN10Item_field15fix_outer_fieldEP3THDPP5FieldPP4Item+0x14c)[0x7fa1f6cf8a1c]
mysqld(_ZN10Item_field10fix_fieldsEP3THDPP4Item+0x4f2)[0x7fa1f6cf9742]
mysqld(_ZN9Item_func10fix_fieldsEP3THDPP4Item+0x1b3)[0x7fa1f6d2f3a3]
mysqld(_Z11setup_condsP3THDP10TABLE_LISTR4ListIS1_EPP4Item+0x1c3)[0x7fa1f6b09573]
mysqld(+0x42f111)[0x7fa1f6b9d111]
mysqld(_ZN30subselect_single_select_engine7prepareEv+0x688)[0x7fa1f6d62788]
mysqld(_ZN14Item_subselect10fix_fieldsEP3THDPP4Item+0xed)[0x7fa1f6d60aed]
mysqld(_Z12setup_fieldsP3THDPP4ItemR4ListIS1_E17enum_mark_columnsPS5_b+0x184)[0x7fa1f6b07594]
mysqld(+0x3f7f7a)[0x7fa1f6b65f7a]
mysqld(_ZN18Prepared_statement7prepareEPKcj+0x6dd)[0x7fa1f6b6771d]
mysqld(_Z22mysql_sql_stmt_prepareP3THD+0x39f)[0x7fa1f6b67caf]
mysqld(_Z21mysql_execute_commandP3THD+0x90e)[0x7fa1f6b4edfe]
mysqld(_Z11mysql_parseP3THDPcjP12Parser_state+0x1e2)[0x7fa1f6b551d2]
mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0x1787)[0x7fa1f6b56f87]
mysqld(_Z24do_handle_one_connectionP3THD+0x28b)[0x7fa1f6c2da5b]
mysqld(handle_one_connection+0x40)[0x7fa1f6c2dac0]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x80a4)[0x7fa1f63360a4]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7fa1f493e04d]

Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (0x7fa1be042408): is an invalid pointer
Connection ID (thread ID): 2
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

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.