Re: kdump failed because of hotplug memory adding in kdump kernel

From: Baoquan <bhe@redhat.com>
To: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Toshi Kani <toshi.kani@hp.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
	tangchen@cn.fujitsu.com, linux-acpi@vger.kernel.org,
	zhangyanfei@cn.fujitsu.com, dyoung@redhat.com,
	Vivek Goyal <vgoyal@redhat.com>
Subject: Re: kdump failed because of hotplug memory adding in kdump kernel
Date: Fri, 10 Jan 2014 18:27:46 +0800	[thread overview]
Message-ID: <20140110102746.GC14074@dhcp-16-105.nay.redhat.com> (raw)
In-Reply-To: <52CFBECB.9040309@jp.fujitsu.com>

On 01/10/14 at 06:35pm, Yasuaki Ishimatsu wrote:
> (2014/01/10 18:14), Baoquan wrote:
> >
> >  >In ns
> >>>object tree, they are not treated as hotplug memory.
> >>
> >>wrong.
> >>They are treated as hotplug memory. But the memory cannot hot removed
> >>because the memory has kernel memory.
> >>
> >>>Otherwise, any hotplug memory which is not reserved for 2nd kernel can
> >>>be parsed and need be added as hotplug memory, and add them into movable
> >>>zone.
> >>
> >>wrong.
> >>The memory is allocated as normal zone and it is offline.
> >
> >Hi,
> >
> >Thanks for answering.
> >
> 
> 
> >I am confused. Now the fact is in 1st kernel memory is reserved for
> >crashkernel and passed to 2nd kernel by exactmap. Then in 2nd kernel,
> >reserved memory regions are added into e820. Later hotplug memory still
> >trigger add_memory, and cause bug I reported.
> 
> Does the issue occur even if you apply the following Prarit's patch to
> your kernel and add no_memory_hotplug boot option to 2nd kernel?
> 
> http://marc.info/?l=linux-acpi&m=138922019607796&w=2

This issue is the same as Prarit's. He posted the formal patch.

But still there are some questions we want to know.

> 
> Thanks,
> Yasuaki Ishimatsu
> 
> >
> >
> >>
> >>>
> >>>Am I right?
> >>>
> >>
> >>>The other question, e820 reserve is done earlier than acpi
> >>>initialization, because acpi_early_init() invocation is very late in
> >>>start_kernel(). Does that means at the very beginning all memorys are in
> >>>e820, later when acpi_early_init is called, hotplug memory is detected,
> >>>they will be moved to different place or need be marked with a specific
> >>>flag?
> >>
> >>No.
> >>
> >>Thanks,
> >>Yasuaki Ishimatsu
> >>
> >
> >--
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> >
> 
> 

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