SIGSEGV in I_P_List from MDL_context::release_lock on INSERT w/ BACKUP LOCK (on optimized builds)

USE test;

CREATE TABLE t1(a INT);

CREATE TABLE t2(b INT);

LOCK TABLES t2 AS a2 WRITE;

BACKUP LOCK t1;

UNLOCK TABLES;

INSERT INTO t1 VALUES(0);

Core was generated by `/test/MD010520-mariadb-10.5.3-linux-x86_64-opt/bin/mysqld --no-defaults --core-'.

Program terminated with signal SIGSEGV, Segmentation fault.

#0  __pthread_kill (threadid=<optimized out>, signo=signo@entry=11)

    at ../sysdeps/unix/sysv/linux/pthread_kill.c:57

[Current thread is 1 (Thread 0x7f0eac431700 (LWP 1009641))]

(gdb) bt

#0  __pthread_kill (threadid=<optimized out>, signo=signo@entry=11) at ../sysdeps/unix/sysv/linux/pthread_kill.c:57

#1  0x0000557891aabac7 in my_write_core (sig=sig@entry=11) at /test/10.5_opt/mysys/stacktrace.c:518

#2  0x000055789146d7ca in handle_fatal_signal (sig=11) at /test/10.5_opt/sql/signal_handler.cc:329

#3  <signal handler called>

#4  0x0000557891370721 in I_P_List<MDL_ticket, I_P_List_adapter<MDL_ticket, &MDL_ticket::next_in_context, &MDL_ticket::prev_in_context>, I_P_List_null_counter, I_P_List_no_push_back<MDL_ticket> >::remove (this=<optimized out>, a=0x7f0e79c44150) at /test/10.5_opt/sql/sql_plist.h:126

#5  MDL_context::release_lock (this=<optimized out>, duration=<optimized out>, ticket=0x7f0e79c44150) at /test/10.5_opt/sql/mdl.cc:2879

#6  0x0000557891370752 in MDL_context::release_lock (this=<optimized out>, ticket=<optimized out>) at /test/10.5_opt/sql/mdl.cc:2897

#7  0x00005578913f5594 in backup_unlock (thd=thd@entry=0x7f0e79c12018) at /test/10.5_opt/sql/backup.cc:397

#8  0x000055789122bd34 in THD::cleanup (this=this@entry=0x7f0e79c12018) at /test/10.5_opt/sql/sql_class.cc:1562

#9  0x00005578911b1b85 in unlink_thd (thd=0x7f0e79c12018) at /test/10.5_opt/sql/mysqld.cc:2617

#10 0x00005578913670a1 in do_handle_one_connection (connect=<optimized out>, connect@entry=0x7f0eaa0329b8, put_in_cache=put_in_cache@entry=true) at /test/10.5_opt/sql/sql_connect.cc:1433

#11 0x0000557891367444 in handle_one_connection (arg=arg@entry=0x7f0eaa0329b8) at /test/10.5_opt/sql/sql_connect.cc:1319

#12 0x00005578916d353a in pfs_spawn_thread (arg=0x7f0eaa04b018) at /test/10.5_opt/storage/perfschema/pfs.cc:2201

#13 0x00007f0eab8586db in start_thread (arg=0x7f0eac431700) at pthread_create.c:463

#14 0x00007f0eaac5688f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95