Re: [PATCH 3/4] coredump: ELF-FDPIC: enable to omit anonymous sharedmemory

From: Hugh Dickins
Date: Fri Mar 02 2007 - 11:57:12 EST


On Fri, 16 Feb 2007, David Howells wrote:
> Robin Holt <holt@xxxxxxx> 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
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