[PATCH v2] x86, kdump: No need to disable ioapic/lapic in crash path

[Eric W. Biederman]

The code and the testing look good, and it has long been desirable to
get rid of this code and reduce the complexity of the kexec on panic
path.

Ingo, Peter, Thomas if one of you could pick this up that would be
wonderful.


Don Zickus <dzickus at redhat.com> writes:

> A customer of ours noticed when their machine crashed, kdump did not
> work but hung instead.  Using their firmware dumping solution they
> grabbed a vmcore and decoded the stacks on the cpus.  What they
> noticed seemed to be a rare deadlock with the ioapic_lock.



[snip]
> I tested kdump on an Ivy Bridge platform, a Pentium4 and an old athlon that
> did not have an ioapic.  All three were successful.
>
> I also tested using lkdtm that would use jprobes to panic the system when
> entering do_IRQ.  The idea was to see how the system reacted with an
> interrupt pending in the second kernel.  My core2 quad successfully kdump'd
> 3 times in a row with no issues.
>
> v2: removed the disable lapic code too
>
> Cc: Eric W. Biederman <ebiederm at xmission.com>
> Cc: Vivek Goyal <vgoyal at redhat.com>
> Signed-off-by: Don Zickus <dzickus at redhat.com>
Reviewed-by: "Eric W. Biederman" <ebiederm at xmission.com>

> ---
>  arch/x86/kernel/crash.c |    8 --------
>  1 files changed, 0 insertions(+), 8 deletions(-)

[snip]

Eric