160927 16:51:56 [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 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: 10.1.17-MariaDB
key_buffer_size=33554432
read_buffer_size=262144
max_used_connections=282
max_threads=1002
thread_count=95
It is possible that mysqld could use up to 
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 566351 K  bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x0x7f175724c008
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 = 0x7f16d74d0110 thread_stack 0x48400
(my_addr_resolve failure: fork)
/usr/sbin/mysqld(my_print_stacktrace+0x2b) [0x7f3145ef616b]
/usr/sbin/mysqld(handle_fatal_signal+0x475) [0x7f3145a52375]
/lib64/libpthread.so.0(+0xf7e0) [0x7f31450577e0]
/usr/sbin/mysqld(Field_long::cmp(unsigned char const*, unsigned char const*)+0xd) [0x7f3145a353bd]
/usr/sbin/mysqld(+0x71957a) [0x7f3145ba057a]
/usr/sbin/mysqld(_downheap+0xe9) [0x7f3145ef5d89]
/usr/sbin/mysqld(queue_remove+0x26) [0x7f3145ef5f46]
/usr/sbin/mysqld(merge_buffers(Sort_param*, st_io_cache*, st_io_cache*, unsigned char*, st_buffpek*, st_buffpek*, st_buffpek*, int)+0x849) [0x7f3145a4f4d9]
/usr/sbin/mysqld(merge_index(Sort_param*, unsigned char*, st_buffpek*, unsigned int, st_io_cache*, st_io_cache*)+0x3c) [0x7f3145a4f83c]
/usr/sbin/mysqld(Unique::merge(TABLE*, unsigned char*, bool)+0x266) [0x7f314598de66]
/usr/sbin/mysqld(Unique::get(TABLE*)+0x119) [0x7f314598e4d9]
/usr/sbin/mysqld(read_keys_and_merge_scans(THD*, TABLE*, List<QUICK_RANGE_SELECT>, QUICK_RANGE_SELECT*, READ_RECORD*, bool, Bitmap<64u>*, Unique**)+0x2ac) [0x7f3145b42f0c]
/usr/sbin/mysqld(QUICK_INDEX_MERGE_SELECT::read_keys_and_merge()+0x59) [0x7f3145b430c9]
/usr/sbin/mysqld(join_init_read_record(st_join_table*)+0x25) [0x7f3145912b15]
/usr/sbin/mysqld(sub_select(JOIN*, st_join_table*, bool)+0x169) [0x7f3145912dd9]
/usr/sbin/mysqld(+0x499b9d) [0x7f3145920b9d]
/usr/sbin/mysqld(JOIN::exec_inner()+0xb50) [0x7f3145933b10]
/usr/sbin/mysqld(JOIN::exec()+0x5d) [0x7f3145935a8d]
/usr/sbin/mysqld(mysql_select(THD*, Item***, TABLE_LIST*, unsigned int, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*)+0x12a) [0x7f314593245a]
/usr/sbin/mysqld(handle_select(THD*, LEX*, select_result*, unsigned long)+0x25d) [0x7f3145935d6d]
/usr/sbin/mysqld(+0x44e982) [0x7f31458d5982]
/usr/sbin/mysqld(mysql_execute_command(THD*)+0x5d7f) [0x7f31458e1c3f]
/usr/sbin/mysqld(mysql_parse(THD*, char*, unsigned int, Parser_state*)+0x28d) [0x7f31458e517d]
/usr/sbin/mysqld(+0x45e27c) [0x7f31458e527c]
/usr/sbin/mysqld(dispatch_command(enum_server_command, THD*, char*, unsigned int)+0x1c63) [0x7f31458e7603]
/usr/sbin/mysqld(do_command(THD*)+0x16b) [0x7f31458e81cb]
/usr/sbin/mysqld(do_handle_one_connection(THD*)+0x17f) [0x7f31459a6a5f]
/usr/sbin/mysqld(handle_one_connection+0x47) [0x7f31459a6bb7]
/usr/sbin/mysqld(+0x95c2cd) [0x7f3145de32cd]
/lib64/libpthread.so.0(+0x7aa1) [0x7f314504faa1]
/lib64/libc.so.6(clone+0x6d) [0x7f3143534aad]

Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (0x7f173f14c020): is an invalid pointer
Connection ID (thread ID): 1575377
Status: NOT_KILLED

Optimizer switch: index_merge=on,index_merge_union=off,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=on,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.

We think the query pointer is invalid, but we will try to print it anyway. 
Query: SELECT SQL_NO_CACHE contact_id FROM users_assignment FORCE INDEX (user_id,company_id) WHERE user_id = '57291' OR (user_id IN(55838,55839,56998,57260,57291,60227,121997,137571,173600,219233,306480,354991,358594,376261,398572,447223,472009,646282,932548,993011,1004609,1021262,1177117,1234288,1283121,1288749,1337771,57291) AND role_id = '1194') OR company_id = '2321'