Messages in this thread | | | Date | Mon, 13 Feb 2017 16:35:10 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCHv4 2/5] x86/mm: introduce mmap{,_legacy}_base |
| |
On Mon, 13 Feb 2017, Dmitry Safonov wrote: > On 02/11/2017 05:13 PM, Thomas Gleixner wrote: > > > -static unsigned long mmap_base(unsigned long rnd) > > > +static unsigned long mmap_base(unsigned long rnd, unsigned long > > > task_size) > > > { > > > unsigned long gap = rlimit(RLIMIT_STACK); > > unsigned long gap_min, gap_max; > > > > /* Add comment what this means */ > > gap_min = SIZE_128M + stack_maxrandom_size(task_size); > > /* Explain that ' /6 * 5' magic */ > > gap_max = (task_size / 6) * 5; > > So, I can't find about those limits on a gap size: > They were introduced by commit 8913d55b6c58 ("i386 virtual memory > layout rework"). > All I could find is that 128Mb limit was more limit on virtual adress > space than on a memory available those days. > And 5/6 of task_size looks like heuristic value. > So I'm not sure, what to write in comments: > that rlimit on stack can't be bigger than 5/6 of task_size? > That looks obvious from the code.
So just leave it alone. 5/6 is pulled from thin air and 128M probably as well. I hoped there would be some reasonable explanation ....
Thanks,
tglx
| |