On Tue, Aug 24, 2010 at 3:03 PM, Luck, Tony <tony.luck@xxxxxxxxx> wrote:
>
> This looks useful too ... but I can't see where the code is that
> made vm_start be PAGE_SIZE lower to begin with. I'd expect to have
> to make a matching change to make vm_end PAGE_SIZE higher for the
> VM_GROWSUP areas.
That's the fault path - the very check_stack_guard_page() logic itself.
In other words, nowhere do we _explicitly_ make the stack larger by
one page, but nowhere do we explicitly size the stack in the first
place! The stack grows by being populated, and every time a new page
is populated, check_stack_guard_page() will have expanded the stack
vma by one extra page.
Linus
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