[root@arch-zfs-test ~]# coredumpctl gdb 1400 PID: 1400 (xl) UID: 0 (root) GID: 0 (root) Signal: 11 (SEGV) Timestamp: Wed 2017-05-03 15:08:09 EEST (12min ago) Command Line: /usr/bin/xl -vvv devd Executable: /usr/bin/xl Control Group: /system.slice/xendriverdomain.service Unit: xendriverdomain.service Slice: system.slice Boot ID: e11f9f8063b24ba6abb709f76694a202 Machine ID: c0f2ee0d91c44644a2ea229db2047149 Hostname: arch-zfs-test Storage: /var/lib/systemd/coredump/core.xl.0.e11f9f8063b24ba6abb709f76694a202.1400.1493813289000000000000.lz4 Message: Process 1400 (xl) of user 0 dumped core. Stack trace of thread 1400: #0 0x00007f00df92b19d search_for_guest (libxenlight.so.4.8) #1 0x00007f00df92b931 backend_watch_callback (libxenlight.so.4.8) #2 0x00007f00df9689da watchfd_callback (libxenlight.so.4.8) #3 0x00007f00df96a612 fd_occurs (libxenlight.so.4.8) #4 0x00007f00df96a6c4 afterpoll_internal (libxenlight.so.4.8) #5 0x00007f00df96bdfd eventloop_iteration (libxenlight.so.4.8) #6 0x00007f00df96cbb1 libxl__ao_inprogress (libxenlight.so.4.8) #7 0x00007f00df92c1dc libxl_device_events_handler (libxenlight.so.4.8) #8 0x0000000000423258 main_devd (xl) #9 0x0000000000408e05 main (xl) #10 0x00007f00def4f511 __libc_start_main (libc.so.6) #11 0x000000000040800a _start (xl) Stack trace of thread 1401: #0 0x00007f00df2e3f7d read (libpthread.so.0) #1 0x00007f00de6bbc3d read_all (libxenstore.so.3.0) #2 0x00007f00de6bd6ca read_message (libxenstore.so.3.0) #3 0x00007f00de6bda1f read_thread (libxenstore.so.3.0) #4 0x00007f00df2da2e7 start_thread (libpthread.so.0) #5 0x00007f00df01b54f __clone (libc.so.6) GNU gdb (GDB) 7.12.1 Copyright (C) 2017 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-pc-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: . Find the GDB manual and other documentation resources online at: . For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from /usr/bin/xl...done. [New LWP 1400] [New LWP 1401] [Thread debugging using libthread_db enabled] Using host libthread_db library "/usr/lib/libthread_db.so.1". Core was generated by `/usr/bin/xl -vvv devd'. Program terminated with signal SIGSEGV, Segmentation fault. #0 0x00007f00df92b19d in search_for_guest (ddomain=0x7fff97ba73a0, domid=0) at libxl.c:3688 3688 if (dguest->domid == domid) [Current thread is 1 (Thread 0x7f00dff7bfc0 (LWP 1400))] (gdb) backtrace full #0 0x00007f00df92b19d in search_for_guest (ddomain=0x7fff97ba73a0, domid=0) at libxl.c:3688 dguest = 0x31352f302f646276 #1 0x00007f00df92b931 in backend_watch_callback (egc=0x7fff97ba72d0, watch=0x7fff97ba73a8, watch_path=0x206e560 "/local/domain/1/backend", event_path=0x2070c90 "/local/domain/1/backend/vbd/0/51728/online") at libxl.c:3874 ddomain = 0x7fff97ba73a0 nested_ao = 0x2070b80 ao = 0x2070b80 gc = 0x2070bc0 p = 0x2070c33 "" path = 0x2070c10 "/local/domain/1/backend/vbd/0/51728" sstate = 0x7f00d40012b0 "5" sonline = 0x7f00d4001290 "0" state = 5 online = 0 rc = 0 num_devs = 0 dev = 0x206ebf0 ddev = 0x0 dguest = 0x0 free_ao = false ---Type to continue, or q to quit--- __func__ = "backend_watch_callback" #2 0x00007f00df9689da in watchfd_callback (egc=0x7fff97ba72d0, ev=0x20708a8, fd=16, events=1, revents=1) at libxl_event.c:574 token = 0x2070cbb "3/0" w = 0x7fff97ba73a8 event = 0x2070c80 epath = 0x2070c90 "/local/domain/1/backend/vbd/0/51728/online" slotnum = 3 counterval = 0 rc = 2 gc = 0x7fff97ba72d0 __func__ = "watchfd_callback" #3 0x00007f00df96a612 in fd_occurs (egc=0x7fff97ba72d0, efd=0x20708a8, revents_ign=1) at libxl_event.c:1200 revents_current = 1 #4 0x00007f00df96a6c4 in afterpoll_internal (egc=0x7fff97ba72d0, poller=0x206fda0, nfds=2, fds=0x20700e0, now=...) at libxl_event.c:1265 revents = 1 gc = 0x7fff97ba72d0 efd = 0x20708a8 __func__ = "afterpoll_internal" __PRETTY_FUNCTION__ = "afterpoll_internal" #5 0x00007f00df96bdfd in eventloop_iteration (egc=0x7fff97ba72d0, ---Type to continue, or q to quit--- poller=0x206fda0) at libxl_event.c:1711 gc = 0x7fff97ba72d0 rc = 0 nfds = 2 now = {tv_sec = 1493813289, tv_usec = 710596} timeout = -1 __func__ = "eventloop_iteration" #6 0x00007f00df96cbb1 in libxl__ao_inprogress (ao=0x206e350, file=0x7f00df9af79b "libxl.c", line=4014, func=0x7f00df9b2d00 <__func__.21414> "libxl_device_events_handler") at libxl_event.c:1997 egc = {gc = {alloc_maxsize = 0, alloc_ptrs = 0x0, owner = 0x20707b0}, occurred_for_callback = {tqh_first = 0x0, tqh_last = 0x7fff97ba72e8}, aos_for_callback = {tqh_first = 0x0, tqh_last = 0x7fff97ba72f8}, aops_for_callback = {tqh_first = 0x0, tqh_last = 0x7fff97ba7308}} gc = 0x206e390 rc = 0 __PRETTY_FUNCTION__ = "libxl__ao_inprogress" __func__ = "libxl__ao_inprogress" #7 0x00007f00df92c1dc in libxl_device_events_handler (ctx=0x20707b0, ao_how=0x0) at libxl.c:4014 ao__ctx = 0x20707b0 ---Type to continue, or q to quit--- ao__rc = 0 ao = 0x206e350 __func__ = "libxl_device_events_handler" egc = {{gc = {alloc_maxsize = 0, alloc_ptrs = 0x0, owner = 0x20707b0}, occurred_for_callback = {tqh_first = 0x0, tqh_last = 0x7fff97ba73e8}, aos_for_callback = {tqh_first = 0x0, tqh_last = 0x7fff97ba73f8}, aops_for_callback = { tqh_first = 0x0, tqh_last = 0x7fff97ba7408}}} gc = 0x206e390 rc = 0 domid = 1 ddomain = {ao = 0x206e350, watch = { path = 0x206e560 "/local/domain/1/backend", callback = 0x7f00df92b703 , slotnum = 3, counterval = 0}, guests = {slh_first = 0x206ff70}} be_path = 0x206fd80 "/local/domain/1/backend" kinds = 0x0 domains = 0x0 devs = 0x0 sstate = 0xffff00ff00000000 state_path = 0x0 state = 0 ---Type to continue, or q to quit--- nkinds = 4294967295 ndomains = 4294901760 ndevs = 6778732 i = -536735504 j = 0 k = 0 __PRETTY_FUNCTION__ = "libxl_device_events_handler" #8 0x0000000000423258 in main_devd (argc=1, argv=0x7fff97ba7608) at xl_cmdimpl.c:9059 ret = 0 opt = -1 daemonize = 1 pidfile = 0x0 opts = {{name = 0x42d3e5 "pidfile", has_arg = 1, flag = 0x0, val = 112}, {name = 0x429059 "help", has_arg = 0, flag = 0x0, val = 104}, {name = 0x0, has_arg = 0, flag = 0x0, val = 0}, { name = 0x0, has_arg = 0, flag = 0x0, val = 0}} #9 0x0000000000408e05 in main (argc=1, argv=0x7fff97ba7608) at xl.c:364 opt = -1 cmd = 0x7fff97ba8f59 "devd" cspec = 0x6363d0 ret = 0 config_data = 0x206df20 ---Type to continue, or q to quit--- config_len = 1303