mm, page_owner: skip unnecessary stack_trace entries

mm, page_owner: skip unnecessary stack_trace entries

The page_owner stacktrace always begin as follows:

  [<ffffff987bfd48f4>] save_stack+0x40/0xc8
  [<ffffff987bfd4da8>] __set_page_owner+0x3c/0x6c

These two entries do not provide any useful information and limits the
available stacktrace depth.  The page_owner stacktrace was skipping
caller function from stack entries but this was missed with commit
f2ca0b557107 ("mm/page_owner: use stackdepot to store stacktrace")

Example page_owner entry after the patch:

  Page allocated via order 0, mask 0x8(ffffff80085fb714)
  PFN 654411 type Movable Block 639 type CMA Flags 0x0(ffffffbe5c7f12c0)
  [<ffffff9b64989c14>] post_alloc_hook+0x70/0x80
  ...
  [<ffffff9b651216e8>] msm_comm_try_state+0x5f8/0x14f4
  [<ffffff9b6512486c>] msm_vidc_open+0x5e4/0x7d0
  [<ffffff9b65113674>] msm_v4l2_open+0xa8/0x224

Link: http://lkml.kernel.org/r/[email protected]
Fixes: f2ca0b557107 ("mm/page_owner: use stackdepot to store stacktrace")
Signed-off-by: Prakash Gupta <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Russell King <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>