On Thu, Oct 19, 2017 at 09:51:04AM -0700, Andrei Vagin wrote:
> Hi,
>
> We run CRIU tests for tip/auto-latest regularly, and a few days ago our
> test job started to detect this warning in a kernel log:
>
> [ 44.235786] WARNING: can't dereference iret registers at ffff8801c5f17fe0
> for ip ffffffff95f0d94b
>
> What does it mean? How critical is it?
>
> Our test job fails if it detects any warning in a kernel log. Maybe we
> need to investigate reasons of this warning and try to eliminate it?
>
> Here are logs:
> https://travis-ci.org/avagin/linux/jobs/289676634
I think it means the unwinder found some bad ORC unwinder metadata. Any
chance you have access to the kernel binary? I need to know what code
corresponds to that ffffffff95f0d94b address.
Or if you can reproduce with the following patch, that should help:
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 570b70d3f604..95b633f0ce51 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -448,7 +448,7 @@ bool unwind_next_frame(struct unwind_state *state)
case ORC_TYPE_REGS_IRET:
if (!deref_stack_regs(state, sp, &state->ip, &state->sp,
false)) {
- orc_warn("can't dereference iret registers at %p for ip
%p\n",
+ orc_warn("can't dereference iret registers at %p for ip
%pB\n",
(void *)sp, (void *)orig_ip);
goto done;
}
