Re: [patch] broken fault_in_pages_readable call in

[Ulrich Weigand]

Andrew Morton wrote:

>Can you explain the bug a bit more completely?  AFACIT, `bytes' here was
>always in the range 0 ..  PAGE_CACHE_SIZE, so how can it have caused large
>amounts of the stack segment to have been faulted in?

'buf' is not page-aligned, so 'buf' + 'bytes' can touch the next page,
which may not be mapped.  In fact, if 'buf' points to the *last* valid
mapped page (before the stack), and the stack ulimit is unlimited, the
VM_GROWSDOWN logic considers this access a request to grow the stack
down to this very page ...

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  Linux on zSeries Development
  Ulrich.Weigand@xxxxxxxxxx
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