From: Meng Xu <email@example.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Andrew Cooper <firstname.lastname@example.org>,
Wei Liu <email@example.com>,
Subject: Re: Question about Xen reboot on panic
Date: Wed, 18 Nov 2015 22:58:48 -0500 [thread overview]
Message-ID: <CAENZ-+kLSwSZ651dB9VaXtB80NdWS2u-m-zduhkfou6G-L_KyA@mail.gmail.com> (raw)
2015-11-13 2:39 GMT-05:00 Jan Beulich <JBeulich@suse.com>:
>>>> On 12.11.15 at 20:54, <firstname.lastname@example.org> wrote:
>> However, the line after that if statement is:
>> which is not in the if ( get_apic_id() != boot_cpu_physical_apicid )
>> So P0 may run this code, and from what I read from this
>> smp_send_stop(), it has the following code:
>> I'm guessing at __stop_this_cpu() when it is on P0, P0 will be
>> stopped. That's why P0 will never have the chance to proceed to the
>> rest of logic in the machine_restart(). Therefore, the machine won't
> The code is quite clear in this regard - smp_send_stop() stops all other
> CPUs, but calls only __stop_this_cpu() (not stop_this_cpu()) for itself.
> I.e. execution is at least supposed to make it back to the caller. Also
> please don't forget that this is working for most everyone else, so
> what you're looking for is more likely some oddity on your system, not
> some general issue.
I see. Hmm, maybe it is because of some oddity on my machine, which is
not a commodity machine but assembled from components. :-(
> (Btw - are you doing this on master, which is what I'd expect you to?
> I ask because the sequence of calls you quote above doesn't match
> with what I see on there. I'd really like to avoid hunting a problem
> long fixed.)
Not really. I added several commits after the master and then "buried"
a bug in the scheduler to cause the system crash when I destroy a VM.
Because the rebooting issue only appears when the kernel crashes in
some cases, so I just tried to use the bug to test if xen kernel can
successfully reboot after crash. I didn't experience kernel crash on
I will come back when I experience the reboot issue on Xen master.
But I still think that Xen should reboot even when the other parts of
Xen (not the reboot logic) has a bug. Maybe I'm wrong?
>> If I move this smp_send_stop(void) into the if statement, Xen will reboot.
>> Do you think this could be a fix?
> Definitely not.
I see the reason now...
This issue does not happen on another machine of mine. Probably it is
because of the oddity on the assembled machine, as Jan said. :-(
Thank you very much for your help and advice!
PhD Student in Computer and Information Science
University of Pennsylvania
next prev parent reply other threads:[~2015-11-19 3:58 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-11 22:49 Question about Xen reboot on panic Meng Xu
2015-11-11 22:54 ` Andrew Cooper
2015-11-11 23:21 ` Meng Xu
2015-11-11 23:34 ` Andrew Cooper
2015-11-12 2:10 ` Meng Xu
2015-11-12 12:52 ` Andrew Cooper
2015-11-12 12:57 ` Wei Liu
2015-11-12 13:16 ` Ian Campbell
2015-11-12 15:09 ` Meng Xu
2015-11-12 15:07 ` Meng Xu
2015-11-12 16:13 ` Meng Xu
2015-11-12 16:57 ` Meng Xu
2015-11-12 17:08 ` Jan Beulich
2015-11-12 19:54 ` Meng Xu
2015-11-13 7:39 ` Jan Beulich
2015-11-19 3:58 ` Meng Xu [this message]
2015-11-19 7:26 ` Jan Beulich
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