[RFC PATCH 0/3] mm/mincore: clean up swap cache helper and PTL

[Kairui Song <ryncsn@gmail.com>]

From: Kairui Song <kasong@tencent.com>

There is a swap cache helper that is only used by mincore. It was
seperated out from mincore some time ago to be shared with other users,
but now mincore is the only user again. So it can be easily merged back
to simplify the code.

Patch 1 clean this up, but I'm not very sure about Patch 2 and 3:

Realizing that the PTL seems only useful for stablizing the swap
cache space now, by grabbing the swap device before looking up the swap
cache space (patch 2), we can drop the PTL locking (patch 3).

Let me know if I'm missing something. With mmap lock, the mincore result
should be reliable enough without the PTL.

Kairui Song (3):
  mm/mincore, swap: consolidate swap cache checking for mincore
  mm/mincore: use a helper for checking the swap cache
  mm/mincore: avoid touching the PTL

 mm/mincore.c    | 53 ++++++++++++++++++++++++++++++++++++++-----------
 mm/swap.h       | 10 ----------
 mm/swap_state.c | 38 -----------------------------------
 3 files changed, 41 insertions(+), 60 deletions(-)

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2.50.1