Greetings, I know absolutely nothing about how crash maintenance is done, and very damn little about crash's gizzard, so please consider the below a bug report, a patch.. or bloody annoying spam, as you see fit.

If the later, listen closely, and you'll hear "Sorry 'bout that" coming from the bottom of your trashcan :) -Mike --- As of kernel commit 0500871f21b2, init_thread_union size became zero, leaving thread_union and machdep->stacksize undetermined, breaking bt. crash> bt 1 PID: 1 TASK: ffff9bf444c02200 CPU: 1 COMMAND: "systemd" #0 [ffffadc8428c3d50] __schedule at ffffffffbd704790 bt: invalid RSP: ffffadc8428c3d50 bt->stackbase/stacktop: ffffadc8428c0000/ffffadc8428c2000 cpu: 1 crash> Fall back to computing size via __end_init_task - __start_init_task. crash> bt 1 PID: 1 TASK: ffff9bf444c02200 CPU: 1 COMMAND: "systemd" #0 [ffffadc8428c3d50] __schedule at ffffffffbd704790 #1 [ffffadc8428c3dd0] schedule at ffffffffbd704bd0 #2 [ffffadc8428c3de8] schedule_hrtimeout_range_clock at ffffffffbd707a66 #3 [ffffadc8428c3e50] ep_poll at ffffffffbd29bac0 #4 [ffffadc8428c3ef8] sys_epoll_wait at ffffffffbd29d612 #5 [ffffadc8428c3f30] do_syscall_64 at ffffffffbd001b79 #6 [ffffadc8428c3f50] entry_SYSCALL_64_after_hwframe at ffffffffbd80009f RIP: 00007f987b26d463 RSP: 00007fff36092e40 RFLAGS: 00000293 RAX: ffffffffffffffda RBX: 000055a96c5accd0 RCX: 00007f987b26d463 RDX: 000000000000005e RSI: 00007fff36092e50 RDI: 0000000000000004 RBP: 00007fff360933c0 R8: 21ad2c5bde36816b R9: 000055a96a66b9e0 R10: 00000000ffffffff R11: 0000000000000293 R12: 0000000000000001 R13: 00007fff36092e50 R14: ffffffffffffffff R15: 0000000000000000 ORIG_RAX: 00000000000000e8 CS: 0033 SS: 002b crash> Signed-off-by: Mike Galbraith <efault(a)gmx.de&gt; --- task.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) --- a/task.c +++ b/task.c @@ -438,8 +438,21 @@ task_init(void) len = SIZE(task_union)); machdep->stacksize = len; } else if (VALID_SIZE(thread_union) && - ((len = SIZE(thread_union)) != STACKSIZE())) + ((len = SIZE(thread_union)) != STACKSIZE())) { machdep->stacksize = len; + } else { + /* + * Post kernel commit 0500871f21b2, init_thread_union size + * became zero. Use __end_init_task - __start_init_task. + */ + if (kernel_symbol_exists("__start_init_task") && + kernel_symbol_exists("__end_init_task")) { + len = symbol_value("__end_init_task"); + len -= symbol_value("__start_init_task"); + ASSIGN_SIZE(thread_union) = len; + machdep->stacksize = len; + } + } MEMBER_OFFSET_INIT(pid_namespace_idr, "pid_namespace", "idr"); MEMBER_OFFSET_INIT(idr_idr_rt, "idr", "idr_rt");