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Date: Fri, 2 Mar 2007 16:55:53 +0000 (GMT)
From: Hugh Dickins <hugh@veritas.com>
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To: David Howells <dhowells@redhat.com>
cc: Robin Holt <holt@sgi.com>,
       "Kawai, Hidehiro" <hidehiro.kawai.ez@hitachi.com>,
       Andrew Morton <akpm@osdl.org>,
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       sugita <yumiko.sugita.yf@hitachi.com>,
       Satoshi OSHIMA <soshima@redhat.com>,
       "Hideo AOKI@redhat" <haoki@redhat.com>
Subject: Re: [PATCH 3/4] coredump: ELF-FDPIC: enable to omit anonymous shared
 memory 
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On Fri, 16 Feb 2007, David Howells wrote:
> Robin Holt <holt@sgi.com> wrote:
> 
> > How about:
> > 		if (vma->vm_mm->coredump_omit_anon_shared) {
> > 
> > Then the calls to maydump() would be unchanged:
> 
> VMAs are a shared resource under NOMMU conditions.

That's a disturbing remark.  Under precisely what NOMMU conditions?

I had thought Robin's suggestion very sensible; and throughout mm/
it has seemed pretty random whether we pass an "mm" argument down
in addition to "vma", or just take vma->vm_mm at whatever level needs.

You seem to be suggesting vma->vm_mm is dangerous when CONFIG_NOMMU,
but we MMU people are scarily unaware of that.  Perhaps you need to
put #ifndef CONFIG_NOMMU around vm_mm in struct vm_area_struct?

Or am I totally misunderstanding?

Hugh