[PATCH v4 0/2] mm/vmalloc.c: improve readability and rewrite vmap_area

[Pengfei Li]

v3 -> v4:
* Base on next-20190711
* patch 1: From: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx> (author)
  - https://lkml.org/lkml/2019/7/3/661
* patch 2: Modify the layout of struct vmap_area for readability

v2 -> v3:
* patch 1-4: Abandoned
* patch 5:
  - Eliminate "flags" (suggested by Uladzislau Rezki)
  - Base on https://lkml.org/lkml/2019/6/6/455
    and https://lkml.org/lkml/2019/7/3/661

v1 -> v2:
* patch 3: Rename __find_vmap_area to __search_va_in_busy_tree
           instead of __search_va_from_busy_tree.
* patch 5: Add motivation and necessary test data to the commit
           message.
* patch 5: Let va->flags use only some low bits of va_start
           instead of completely overwriting va_start.

The current implementation of struct vmap_area wasted space.

After applying this commit, sizeof(struct vmap_area) has been
reduced from 11 words to 8 words.

Pengfei Li (1):
  mm/vmalloc.c: Modify struct vmap_area to reduce its size

Uladzislau Rezki (Sony) (1):
  mm/vmalloc: do not keep unpurged areas in the busy tree

 include/linux/vmalloc.h | 40 ++++++++++++++++-----
 mm/vmalloc.c            | 79 ++++++++++++++++++++++++++++-------------
 2 files changed, 86 insertions(+), 33 deletions(-)

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2.21.0