linux-kernel - Re: [PATCH v5 0/6] x86/apic: Fix restoring boot irq mode in reboot and kexec/kdump

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Message-ID: <20180217101759.4hn7tdqgudxcq4rk@gmail.com>
Date:   Sat, 17 Feb 2018 11:17:59 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Baoquan He <bhe@...hat.com>, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, x86@...nel.org, douly.fnst@...fujitsu.com,
        joro@...tes.org, uobergfe@...hat.com, prarit@...hat.com
Subject: Re: [PATCH v5 0/6] x86/apic: Fix restoring boot irq mode in reboot
 and kexec/kdump


* Eric W. Biederman <ebiederm@...ssion.com> wrote:

> Ingo Molnar <mingo@...nel.org> writes:
> 
> > * Baoquan He <bhe@...hat.com> wrote:
> >
> >> This is v5 post. Newly added patch 0002 includes the change
> >> related to KEXEC_JUMP path. Patch 0003 only includes the
> >> regression fix.
> >> 
> >> A regression bug was introduced in below commit.
> >> commit 522e66464467 ("x86/apic: Disable I/O APIC before shutdown of the local APIC")
> >> 
> >> It caused the action to fail that we try to restore boot irq mode
> >> in reboot and kexec/kdump. Details can be seen in patch 0003.
> >> 
> >> Warning can always be seen during kdump kernel boot on qemu/kvm
> >> platform. Our customer even saw casual kdump kernel hang once in
> >> ~30 attempts during stress testing of kdump on KVM machine.
> >> 
> >> v4->v5:
> >>   Take out the change related to KEXEC_JUMP to a new patch 0002
> >>   according to Eric's suggestion.
> >>   Patch 0003 in this series only includes the regression fix.
> >> 
> >> v3->v4:
> >>   Eric pointed out that in patch 0002 the change related to
> >>   KEXEC_JUMP is not right.
> >>   Correct it.
> >> 
> >>   Add Fixes tag and Cc to stable.
> >
> > Eric, are these patches looking good to you now?
> 
> The result of applying the patches looks good.
> Barring whatever fix to header files that kbuild seems to find necessary.
> 
> I wish patches 1 2 and 4 were all the same patch.  That I think would
> make reading the patches a bit easier, and make the backports clearer.
> But at this point that is just me bike-shedding.
> 
> Reviewed-by: "Eric W. Biederman" <ebiederm@...ssion.com>

Thank you!

	Ingo