linux-kernel - Re: [PATCH v8 9/9] vmcore: support mmap() on /proc/vmcore

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Message-Id: <20130603174351.d04b2ac71d1bab0df242e0ba@mxc.nes.nec.co.jp>
Date:	Mon, 3 Jun 2013 17:43:51 +0900
From:	Atsushi Kumagai <kumagai-atsushi@....nes.nec.co.jp>
To:	muvarov@...il.com
Cc:	zhangyanfei@...fujitsu.com, d.hatayama@...fujitsu.com,
	akpm@...ux-foundation.org, riel@...hat.com, hughd@...gle.com,
	jingbai.ma@...com, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org, lisa.mitchell@...com,
	linux-mm@...ck.org, ebiederm@...ssion.com,
	kosaki.motohiro@...fujitsu.com, walken@...gle.com, cpw@....com,
	vgoyal@...hat.com
Subject: Re: [PATCH v8 9/9] vmcore: support mmap() on /proc/vmcore

Hello Maxim,

On Thu, 30 May 2013 14:30:01 +0400
Maxim Uvarov <muvarov@...il.com> wrote:

> 2013/5/30 Zhang Yanfei <zhangyanfei@...fujitsu.com>
> 
> > On 05/30/2013 05:14 PM, Maxim Uvarov wrote:
> > >
> > >
> > >
> > > 2013/5/27 HATAYAMA Daisuke <d.hatayama@...fujitsu.com <mailto:
> > d.hatayama@...fujitsu.com>>
> > >
> > >     (2013/05/24 18:02), Maxim Uvarov wrote:
> > >
> > >
> > >
> > >
> > >         2013/5/24 Andrew Morton <akpm@...ux-foundation.org <mailto:
> > akpm@...ux-foundation.org> <mailto:akpm@...ux-foundation.__org <mailto:
> > akpm@...ux-foundation.org>>>
> > >
> > >
> > >             On Thu, 23 May 2013 14:25:48 +0900 HATAYAMA Daisuke <
> > d.hatayama@...fujitsu.com <mailto:d.hatayama@...fujitsu.com> <mailto:
> > d.hatayama@...fujitsu.__com <mailto:d.hatayama@...fujitsu.com>>> wrote:
> > >
> > >              > This patch introduces mmap_vmcore().
> > >              >
> > >              > Don't permit writable nor executable mapping even with
> > mprotect()
> > >              > because this mmap() is aimed at reading crash dump memory.
> > >              > Non-writable mapping is also requirement of
> > remap_pfn_range() when
> > >              > mapping linear pages on non-consecutive physical pages;
> > see
> > >              > is_cow_mapping().
> > >              >
> > >              > Set VM_MIXEDMAP flag to remap memory by remap_pfn_range
> > and by
> > >              > remap_vmalloc_range_pertial at the same time for a single
> > >              > vma. do_munmap() can correctly clean partially remapped
> > vma with two
> > >              > functions in abnormal case. See zap_pte_range(),
> > vm_normal_page() and
> > >              > their comments for details.
> > >              >
> > >              > On x86-32 PAE kernels, mmap() supports at most 16TB
> > memory only. This
> > >              > limitation comes from the fact that the third argument of
> > >              > remap_pfn_range(), pfn, is of 32-bit length on x86-32:
> > unsigned long.
> > >
> > >             More reviewing and testing, please.
> > >
> > >
> > >         Do you have git pull for both kernel and userland changes? I
> > would like to do some more testing on my machines.
> > >
> > >         Maxim.
> > >
> > >
> > >     Thanks! That's very helpful.
> > >
> > >     --
> > >     Thanks.
> > >     HATAYAMA, Daisuke
> > >
> > > Any update for this? Where can I checkout all sources?
> >
> > This series is now in Andrew Morton's -mm tree.
> >
> > Ok, and what about makedumpfile changes? Is it possible to fetch them from
> somewhere?

You can fetch them from here, "mmap" branch is the change:

  git://git.code.sf.net/p/makedumpfile/code

And they will be merged into v1.5.4.


Thanks
Atsushi Kumagai
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