Provide histogram of stack sizes for the exited threads:
Example outputs:
Intel:
$ grep kstack /proc/vmstat
kstack_1k 3
kstack_2k 188
kstack_4k 11391
kstack_8k 243
kstack_16k 0

ARM with 64K page_size:
$ grep kstack /proc/vmstat
kstack_1k 1
kstack_2k 340
kstack_4k 25212
kstack_8k 1659
kstack_16k 0
kstack_32k 0
kstack_64k 0

Changelog:
v5:
Uninlined stack_not_used() and kstack_histogram()  per mailing list
discussion
Use count_vm_event() instead of this_cpu_inc()
Increase memcg_event limit from s8_max to u8_max.

Pasha Tatashin (2):
  vmstat: Kernel stack usage histogram
  task_stack: uninline stack_not_used

Shakeel Butt (1):
  memcg: increase the valid index range for memcg stats

 include/linux/sched/task_stack.h | 18 ++--------
 include/linux/vm_event_item.h    | 24 ++++++++++++++
 kernel/exit.c                    | 57 ++++++++++++++++++++++++++++++++
 kernel/sched/core.c              |  4 +--
 mm/memcontrol.c                  | 50 ++++++++++++++++------------
 mm/vmstat.c                      | 24 ++++++++++++++
 6 files changed, 137 insertions(+), 40 deletions(-)

-- 
2.45.2.1089.g2a221341d9-goog