Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR

[Andy Lutomirski]

On Wed, Jan 4, 2017 at 6:19 AM, Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> wrote:
> On Tue, Jan 03, 2017 at 10:27:22AM -0800, Andy Lutomirski wrote:
>> On Tue, Jan 3, 2017 at 8:04 AM, Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> wrote:
>> > And what about stack? I'm not sure that everybody would be happy with
>> > stack in the middle of address space.
>>
>> I would, personally.  I think that, for very large address spaces, we
>> should allocate a large block of stack and get rid of the "stack grows
>> down forever" legacy idea.  Then we would never need to worry about
>> the stack eventually hitting some other allocation.  And 2^57 bytes is
>> hilariously large for a default stack.
>
> The stack in the middle of address space can prevent creating other huuuge
> contiguous mapping. Databases may want this.

Fair enough.  OTOH, 2^47 is nowhere near the middle if we were to put
it near the top of the legacy address space.