Previously a fail of cmd "bt -f/-F" observed: crash> bt -f PID: 3359 TASK: 28b01a09400 CPU: 0 COMMAND: "runtest.sh" LOWCORE INFO: ... -general registers: 0x0000000034dd9140 0x0000039600000002 0x00000396cad7dfa0 0x0000028b03ba5000 ... 0000028c6e9fffd8: 0000000000000000 0000000000000000 0000028c6e9fffe8: 0000000000000000 0000000000000000 0000028c6e9ffff8: 0000000000000000bt: seek error: kernel virtual address: 28c6ea00000 type: "readmem_ul" The root cause is kernel commit ce3dc447493ff ("s390: add support for virtually mapped kernel stacks") replaced "panic_task" by "nodat_stack", which leading a wrong stack base/top calculation. This patch fix the bug by checking if nodat_stack member is exist in struct lowcore. Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; --- s390x.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/s390x.c b/s390x.c index 794ae82..ad69184 100644 --- a/s390x.c +++ b/s390x.c @@ -1797,7 +1797,13 @@ static void s390x_back_trace_cmd(struct bt_info *bt) cpu, lowcore, &low, &high); sp = show_trace(bt, cnt, sp, low, high); } - get_int_stack("panic_stack", cpu, lowcore, &low, &high); + if (MEMBER_EXISTS("lowcore", "nodat_stack")) { + get_int_stack("nodat_stack", + cpu, lowcore, &low, &high); + } else { + get_int_stack("panic_stack", + cpu, lowcore, &low, &high); + } sp = show_trace(bt, cnt, sp, low, high); get_int_stack("async_stack", cpu, lowcore, &low, &high); sp = show_trace(bt, cnt, sp, low, high); -- 2.40.1