linux-kernel - Re: The current SME implementation fails kexec/kdump kernel booting.

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Message-ID: <20190611102428.GF26148@MiWiFi-R3L-srv>
Date:   Tue, 11 Jun 2019 18:24:28 +0800
From:   Baoquan He <bhe@...hat.com>
To:     lijiang <lijiang@...hat.com>
Cc:     "Lendacky, Thomas" <Thomas.Lendacky@....com>,
        "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: The current SME implementation fails kexec/kdump kernel booting.

Hi Tom,

On 06/11/19 at 05:52pm, lijiang wrote:
> After applied Tom's patch, i changed the reserved memory(for crash kernel) to the
> above 256M(>256M), such as crashkernel=320M or 384M,512M..., the kdump kernel can
> work and successfully dump the vmcore.
> 
> But the kdump kernel always happened the panic or could not boot successfully in
> the 256M(<= 256M) case, and on HP machine, i noticed that it printed OOM, the kdump
> kernel was too smaller memory. But i never see the OOM on speedway machine(probably
> related to the earlyprintk, it doesn't work and it loses many logs).
> 
> After removing the option 'CONFIG_DEBUG_INFO' from .config, i tested again, the kdump
> kernel did not happen the panic in the 256M(crashkernel=256M), the kdump kernel can
> work and succeed to dump the vmcore on HP machine or speedway machine.
> 
> It seems that the small memory caused the previous failure in kdump kernel. I would
> suggest to post this patch to upstream. What's your opinion? Tom, Baoquan and other
> people. Or do you have any comment?

As Lianbo said at above, the previous failure in kdump kernel is caused
by OOM. Just the log on speedway is incomplete, I am not sure what
happened. Now after investigation, your patch works to fix the issue.
Could you post it for riviewing?

Thanks
Baoquan