On Tue, Nov 07, 2017 at 02:05:42PM +0100, Florian Weimer wrote: > On 11/07/2017 12:44 PM, Kirill A. Shutemov wrote: > > On Tue, Nov 07, 2017 at 12:26:12PM +0100, Florian Weimer wrote: > > > On 11/07/2017 12:15 PM, Kirill A. Shutemov wrote: > > > > > > > > First of all, using addr and MAP_FIXED to develop our heuristic can > > > > > never really give unchanged ABI. It's an in-band signal. brk() is a > > > > > good example that steadily keeps incrementing address, so depending > > > > > on malloc usage and address space randomization, you will get a brk() > > > > > that ends exactly at 128T, then the next one will be > > > > > > DEFAULT_MAP_WINDOW, and it will switch you to 56 bit address space. > > > > > > > > No, it won't. You will hit stack first. > > > > > > That's not actually true on POWER in some cases. See the process maps I > > > posted here: > > > > > > <https://marc.info/?l=linuxppc-embedded&m=150988538106263&w=2> > > > > Hm? I see that in all three cases the [stack] is the last mapping. > > Do I miss something? > > Hah, I had not noticed. Occasionally, the order of heap and stack is > reversed. This happens in approximately 15% of the runs. Heh. I guess ASLR on Power is too fancy :) That's strange layout. It doesn't give that much (relatively speaking) virtual address space for both stack and heap to grow. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
