Comment 6 for bug 1597143

+bt
#0 0x00007f2f9c85d741 in __pthread_kill (threadid=<optimized out>, signo=6) at ../nptl/sysdeps/unix/sysv/linux/pthread_kill.c:61
#1 0x000000000183b0e8 in my_write_core (sig=6) at /git/PS-5.7_dbg/mysys/stacktrace.c:247
#2 0x0000000000e76cd3 in handle_fatal_signal (sig=6) at /git/PS-5.7_dbg/sql/signal_handler.cc:223
#3 <signal handler called>
#4 0x00007f2f9abf65f7 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#5 0x00007f2f9abf7ce8 in __GI_abort () at abort.c:90
#6 0x0000000001bab987 in ut_dbg_assertion_failed (expr=0x21be938 "log_sys->buf == ut_align(log_sys->buf_ptr, srv_log_write_ahead_size)", file=0x21be0d8 "/git/PS-5.7_dbg/storage/innobase/log/log0log.cc", line=1256) at /git/PS-5.7_dbg/storage/innobase/ut/ut0dbg.cc:67
#7 0x0000000001a10fee in log_buffer_switch () at /git/PS-5.7_dbg/storage/innobase/log/log0log.cc:1255
#8 0x0000000001a11636 in log_write_up_to (lsn=2501989, flush_to_disk=true) at /git/PS-5.7_dbg/storage/innobase/log/log0log.cc:1414
#9 0x0000000001a11988 in log_buffer_sync_in_background (flush=true) at /git/PS-5.7_dbg/storage/innobase/log/log0log.cc:1518
#10 0x0000000001b40791 in srv_sync_log_buffer_in_background () at /git/PS-5.7_dbg/storage/innobase/srv/srv0srv.cc:2342
#11 0x0000000001b40d4b in srv_master_do_active_tasks () at /git/PS-5.7_dbg/storage/innobase/srv/srv0srv.cc:2515
#12 0x0000000001b419c4 in srv_master_thread (arg=0x0) at /git/PS-5.7_dbg/storage/innobase/srv/srv0srv.cc:2772
#13 0x00007f2f9c858dc5 in start_thread (arg=0x7f2f789fd700) at pthread_create.c:308
#14 0x00007f2f9acb721d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113