This may not be relevant to most of you, yet, as the SLES12 and RHEL7 beta programs are not quite open to the public, but similar problems may happen to you with other distributions that do backports of patches as well.
If you see error messages such as the following when compiling VirtualBox guest additions for your Linux guest:
/tmp/vbox.0/r0drv/linux/memobj-r0drv-linux.c: In function ‘rtR0MemObjNativeMapUser’: /tmp/vbox.0/r0drv/linux/memobj-r0drv-linux.c:1542:26: error: ‘struct mm_struct’ has no member named ‘numa_next_reset’ pTask->mm->numa_next_reset = jiffies + 0x7fffffffffffffffUL; ^ make: *** [/tmp/vbox.0/r0drv/linux/memobj-r0drv-linux.o] Error 1 make: *** [_module_/tmp/vbox.0] Error 2 make: *** [vboxguest] Error 2
You should take a look at VirtualBox ticket #12638 which deals with the removal of the numa_balancing_scan_period_reset sysctl and related data structures. I just submitted a patch there that tries to address the issue of distro vendor backports of patches in a less expensive way than grepping header files.
If you want to try it out, also have a look at How to recreate / build VirtualBox guest additions ISO image VBoxGuestAdditions.iso.