Merge branch into tip/master: 'core/core'

Merge branch into tip/master: 'core/core'

* core/core:
    0ce055f85335 fork: Use IS_ENABLED() in account_kernel_stack()
    e540bf3162e8 fork: Only cache the VMAP stack in finish_task_switch()
    1a03d3f13ffe fork: Move task stack accounting to do_exit()
    f1c1a9ee00e4 fork: Move memcg_charge_kernel_stack() into CONFIG_VMAP_STACK
    7865aba3ade4 fork: Don't assign the stack pointer in dup_task_struct()
    2bb0529c0bc0 fork, IA64: Provide alloc_thread_stack_node() for IA64
    546c42b2c5c1 fork: Duplicate task_struct before stack allocation
    be9a2277cafd fork: Redo ifdefs around task stack handling

Signed-off-by: Ingo Molnar <mingo@kernel.org>