Re: [PATCH V2 1/2] kexec: Make a pair of map/unmap reserved pages in error path

From	Minfei Huang <mhuang@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH V2 1/2] kexec: Make a pair of map/unmap reserved pages in error path
Date	2016-03-02 04:00 +0100
Message-ID	<r85b4-1lk-11@gated-at.bofh.it> (permalink)
References	<r7Nxw-6uW-7@gated-at.bofh.it> <r7Nxw-6uW-5@gated-at.bofh.it> <r80uJ-6zV-3@gated-at.bofh.it>
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On 03/01/16 at 01:56pm, Andrew Morton wrote:
> On Tue,  1 Mar 2016 16:02:28 +0800 Minfei Huang <mnfhuang@gmail.com> wrote:
> 
> > For some arch, kexec shall map the reserved pages, then use them, when
> > we try to start the kdump service.
> 
> Which architectures are these, by the way?

Hi.

This patch only affects s390. The others doesn't implement the interface
of crash_unmap_reserved_pages and crash_map_reserved_pages.

> 
> > kexec may return directly, without unmaping the reserved pages, if it
> > fails during starting service. To fix it, we make a pair of map/unmap
> > reserved pages both in generic path and error path.
> 
> I'm having trouble understanding the urgency of this patch.  Do you
> think it is needed in 4.5?  -stable?  If so, why?

IMHO, it is fine in next release as it isn't a urgent patch. Kernel can
work well without any risk, although the reseverd pages are not unmaped
before returning in error path.

Thanks
Minfei

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[PATCH V2 1/2] kexec: Make a pair of map/unmap reserved pages in error path Minfei Huang <mnfhuang@gmail.com> - 2016-03-01 09:10 +0100
  Re: [PATCH V2 1/2] kexec: Make a pair of map/unmap reserved pages  in error path Andrew Morton <akpm@linux-foundation.org> - 2016-03-01 23:00 +0100
    Re: [PATCH V2 1/2] kexec: Make a pair of map/unmap reserved pages in  error path Minfei Huang <mhuang@redhat.com> - 2016-03-02 04:00 +0100

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