Re: [PATCH v7 00/12] kexec kernel efi runtime support

From: Dave Young
Date: Tue Dec 24 2013 - 22:09:59 EST

On 12/23/13 at 07:36am, Matt Fleming wrote:
> On Sun, 22 Dec, at 02:27:01PM, Toshi Kani wrote:
> >
> > The kexec branch is missing the following change, which is required for
> > fast reboot with multi-cpus.
> >
> > commit 279f1df915c3a6ed3075d98a849705bf53851f99
> > Author: Vivek Goyal <vgoyal@xxxxxxxxxx>
> > Date: Tue Nov 26 10:25:28 2013 +0800
> >
> > kexec: migrate to reboot cpu
> >
> > With this change added, I confirmed that the branch kernel works fine.
> I can't find that commit in Linus' tree. Where is it from?

Previously it was in Andrew's mm tree, currently it's below commit in linus tree:

commit c97102ba96324da330078ad8619ba4dfe840dbe3
Author: Vivek Goyal <vgoyal@xxxxxxxxxx>
Date: Wed Dec 18 17:08:31 2013 -0800

kexec: migrate to reboot cpu

Commit 1b3a5d02ee07 ("reboot: move arch/x86 reboot= handling to generic
kernel") moved reboot= handling to generic code. In the process it also
removed the code in native_machine_shutdown() which are moving reboot
process to reboot_cpu/cpu0.

I guess that thought must have been that all reboot paths are calling
migrate_to_reboot_cpu(), so we don't need this special handling. But
kexec reboot path (kernel_kexec()) is not calling
migrate_to_reboot_cpu() so above change broke kexec. Now reboot can
happen on non-boot cpu and when INIT is sent in second kerneo to bring
up BP, it brings down the machine.

So start calling migrate_to_reboot_cpu() in kexec reboot path to avoid
this problem.

Bisected by WANG Chao.

Reported-by: Matthew Whitehead <mwhitehe@xxxxxxxxxx>
Reported-by: Dave Young <dyoung@xxxxxxxxxx>
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Tested-by: Baoquan He <bhe@xxxxxxxxxx>
Tested-by: WANG Chao <chaowang@xxxxxxxxxx>
Acked-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
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