linux-kernel - Re: [PATCH v2] s390/kexec: Consolidate crash_map/unmap_reserved_pages() and arch_kexec_protect(unprotect)

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Message-ID: <57039223.7020903@redhat.com>
Date:	Tue, 5 Apr 2016 18:23:31 +0800
From:	Xunlei Pang <xpang@...hat.com>
To:	Michael Holzheu <holzheu@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	akpm@...ux-foundation.org, ebiederm@...ssion.com,
	Minfei Huang <mhuang@...hat.com>,
	Vivek Goyal <vgoyal@...hat.com>, Baoquan He <bhe@...hat.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>
Subject: Re: [PATCH v2] s390/kexec: Consolidate
 crash_map/unmap_reserved_pages() and
 arch_kexec_protect(unprotect)_crashkres()

On 2016/04/05 at 17:13, Michael Holzheu wrote:
> Hello Xunlei,
>
> On Tue,  5 Apr 2016 15:09:59 +0800
> Xunlei Pang <xlpang@...hat.com> wrote:
>> Commit 3f625002581b ("kexec: introduce a protection mechanism
>> for the crashkernel reserved memory") is a similar mechanism
>> for protecting the crash kernel reserved memory to previous
>> crash_map/unmap_reserved_pages() implementation, the new one
>> is more generic in name and cleaner in code (besides, some
>> arch may not be allowed to unmap the pgtable).
>>
>> Therefore, this patch consolidates them, and uses the new
>> arch_kexec_protect(unprotect)_crashkres() to replace former
>> crash_map/unmap_reserved_pages() which by now has been only
>> used by S390.
>>
>> The consolidation work needs the crash memory to be mapped
>> initially, so get rid of S390 crash kernel memblock removal
>> in reserve_crashkernel().

Oops, the final paragraph of the changelog should be changed to:
The consolidation work needs the crash memory to be mapped
initially, this is done in machine_kdump_pm_init() which is run
after reserve_crashkernel(). Once kdump kernel is loaded, the
new arch_kexec_protect_crashkres() implemented for S390 will
actually unmap the pgtable like before.

> If you fix this comment, I am fine with your patch.
>
> Acked-by: Michael Holzheu <holzheu@...ux.vnet.ibm.com>
>

Thanks,
Xunlei