Re: [patch] mm: sparsemem memory_present() memory corruption fix

[KAMEZAWA Hiroyuki]

On Tue, 15 Apr 2008 19:00:18 -0700
"Yinghai Lu" <yhlu.kernel@xxxxxxxxx> wrote:

> On Tue, Apr 15, 2008 at 6:30 PM, Yinghai Lu <yhlu.kernel@xxxxxxxxx> wrote:
> >
> > On Tue, Apr 15, 2008 at 6:17 PM, Ingo Molnar <mingo@xxxxxxx> wrote:
> >  >
> >  >  * Ingo Molnar <mingo@xxxxxxx> wrote:
> >  >
> >  >  > > > this is the only call to memory_present() we do in 32-bit arch
> >  >  > > > setup, so it's required.
> >  >  > >
> >  >  > > We could clip there if SPARSEMEM is configured. I wonder if this
> >  >  > > affects other platforms that need HIGHMEM support?
> >  >  >
> >  >  > clip where and what?
> >  >
> >  >  i.e. as per my previous argument i'd consider the need to sanitize the
> >  >  calls in the architecture fundamentally wrong.
> >  >
> >  >  whether the core code emits a warning or allows the call is an
> >  >  additional question i mention in the changelog - but the core sparse
> >  >  memory code should _definitely_ not silently overflow a key internal
> >  >  array ... (of which data structure the architecture code is not even
> >  >  aware of)
> >
> >  or you can move that check into find_max_pfn for x86_32? so it will
> >  not affect other platform regarding Christoph's concern?
> >
> the patch doesn't have side effects on x86_64.
> 
also no side effects on my ia64/NUMA box, which has sparse physical memory map.

Thanks,
-Kame



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