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

From: Atsushi Kumagai
Date: Mon Jun 03 2013 - 05:03:30 EST


Hello Maxim,

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

> 2013/5/30 Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
>
> > On 05/30/2013 05:14 PM, Maxim Uvarov wrote:
> > >
> > >
> > >
> > > 2013/5/27 HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx <mailto:
> > d.hatayama@xxxxxxxxxxxxxx>>
> > >
> > > (2013/05/24 18:02), Maxim Uvarov wrote:
> > >
> > >
> > >
> > >
> > > 2013/5/24 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx <mailto:
> > akpm@xxxxxxxxxxxxxxxxxxxx> <mailto:akpm@xxxxxxxxxxxxxxxxxxxxxx <mailto:
> > akpm@xxxxxxxxxxxxxxxxxxxx>>>
> > >
> > >
> > > On Thu, 23 May 2013 14:25:48 +0900 HATAYAMA Daisuke <
> > d.hatayama@xxxxxxxxxxxxxx <mailto:d.hatayama@xxxxxxxxxxxxxx> <mailto:
> > d.hatayama@xxxxxxxxxxxxxxxx <mailto:d.hatayama@xxxxxxxxxxxxxx>>> 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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