Don, thanks for ccing me.
On 01/16/18 at 07:47am, Don Zickus wrote:
(cc'ing Dae Young)
On Tue, Jan 16, 2018 at 07:41:36AM -0500, Josh Boyer wrote:
> On Tue, Jan 9, 2018 at 1:51 PM, Maxim Burgerhout <maxim(a)wzzrd.com> wrote:
> > I'm getting kernel panics in a VM that functions as a hypervisor, the
> > I spin up the nested guest (on AMD ThreadRipper / Fedora 27). That is
> > annoying, of course, so I try to be a good citizen and file a bug.
> > For some reason though, I cannot get the core dumped. I get a core fine with
> > sysrq, but not with this actual panic. I've followed  to set up kdump
> > crash, but everytime I trigger the crash and see my VM reboot, I see an
> > empty /var/crash afterwards.
> > As was able to get the vmcore written to /var/crash on in a RHEL7 guest,
> > starting to suspect a bug, but I'm unsure.
One thing need check is if kdump service started successfully before the
crash, ie. check /sys/kernel/kexec_crash_loaded.
If use self-build kernel, you can check to use below patch for testing:
It is useful to print kdump kernel loaded status in dump_stack()
especially when panic happens so that we can differenciate
kdump kernel early hang and a normal panic in a bug report.
Signed-off-by: Dave Young <dyoung(a)redhat.com>
kernel/printk/printk.c | 3 +++
1 file changed, 3 insertions(+)
@@ -48,6 +48,7 @@
@@ -3127,6 +3128,8 @@ void dump_stack_print_info(const char *l
if (dump_stack_arch_desc_str != '\0')
printk("%sHardware name: %s\n",
+ if (kexec_crash_loaded())
+ printk("%skdump kernel loaded\n", log_lvl);
> > Any pointers on how to debug this?
> >  https://fedoraproject.org/wiki/How_to_use_kdump_to_debug_kernel_crashes
> Adding the Fedora kernel list.
> Kdump isn't automatically tested in Fedora and while it can work, it
> can often be broken as well. There might be someone on the kernel
> list that is more familiar with the current state of kdump support in
> Fedora, or alternative methods for getting the kernel backtrace.
Yes, since Fedora kernel updates frequently, it is not a surprise that
kdump does not work. But it is always good to report a bug against
"kexec-tools" component or "kernel" -> "Kexec/kdump"
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