linux-kernel - Re: 4.14.9 doesn't boot (regression)

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Message-ID: <alpine.LRH.2.00.1712301049580.1449@gjva.wvxbf.pm>
Date:   Sat, 30 Dec 2017 10:53:33 +0100 (CET)
From:   Jiri Kosina <jikos@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
cc:     Toralf Förster <toralf.foerster@....de>,
        Alexander Tsoy <alexander@...y.me>,
        Andy Lutomirski <luto@...capital.net>,
        stable <stable@...r.kernel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        the arch/x86 maintainers <x86@...nel.org>
Subject: Re: 4.14.9 doesn't boot (regression)

On Fri, 29 Dec 2017, Linus Torvalds wrote:

> Ok, so what does seem to be consistent for everybody is that 
> double-fault in the NMI backtrace.
> 
> So the fact that the NMI always hits on a double-fault does make me
> suspect that it's a infinite stream of double-faults, and that is
> presumably also what causes the RCU timeout.

As I've been fighting with recursive double-faults lately (backporting PTI 
to ancient kernels), I can tell you that this is not the symptom you'd be 
seeing in such case; recursive double fault pretty quickly overflows the 
interrupt stack and triple-faults.

-- 
Jiri Kosina
SUSE Labs