[PATCH v5 0/7] mm: Use slab_list list_head instead of lru

[Tobin C. Harding]

Hi Andrew,

Here is the updated series that caused the bug found by 0day test
robot.  To ease the load on your memory, this series is aimed at
replacing the following:

Original buggy series:

 mm-remove-stale-comment-from-page-struct.patch
 slub-use-slab_list-instead-of-lru.patch
 slab-use-slab_list-instead-of-lru.patch
 slob-use-slab_list-instead-of-lru.patch
 slub-add-comments-to-endif-pre-processor-macros.patch
 slob-respect-list_head-abstraction-layer.patch
 list-add-function-list_rotate_to_front.patch

And the bug fix patch:

 slob-only-use-list-functions-when-safe-to-do-so.patch

Applies cleanly on top of Linus' tree (tag: v5.1-rc3).

This series differs from the bug fix above by adding a separate return
parameter to slob_page_alloc() instead of using a double pointer.  This
is defensive in case later someone adds code that accesses sp (struct
page *), also it is easier to read/verify the code since its less 'tricky'.

Tested by building and booting a kernel using the SLOB allocator and
with CONFIG_DEBUG_LIST.

>From v4 ... 

Currently the slab allocators (ab)use the struct page 'lru' list_head.
We have a list head for slab allocators to use, 'slab_list'.

During v2 it was noted by Christoph that the SLOB allocator was reaching
into a list_head, this version adds 2 patches to the front of the set to
fix that.

Clean up all three allocators by using the 'slab_list' list_head instead
of overloading the 'lru' list_head.

Changes since v4:
 - Add return parameter to slob_page_alloc() to indicate whether the
   page is removed from the freelist during allocation.
 - Only do list rotate optimisation if the page was _not_ removed from
   the freelist (fix bug found by 0day test robot).

Changes since v3:

 - Change all ->lru to ->slab_list in slob (thanks Roman).

Changes since v2:

 - Add list_rotate_to_front().
 - Fix slob to use list_head API.
 - Re-order patches to put the list.h changes up front.
 - Add acks from Christoph.

Changes since v1:

 - Verify object files are the same before and after the patch set is
   applied (suggested by Matthew).
 - Add extra explanation to the commit logs explaining why these changes
   are safe to make (suggested by Roman).
 - Remove stale comment (thanks Willy).


thanks,
Tobin.


Tobin C. Harding (7):
  list: Add function list_rotate_to_front()
  slob: Respect list_head abstraction layer
  slob: Use slab_list instead of lru
  slub: Add comments to endif pre-processor macros
  slub: Use slab_list instead of lru
  slab: Use slab_list instead of lru
  mm: Remove stale comment from page struct

 include/linux/list.h     | 18 ++++++++++++
 include/linux/mm_types.h |  2 +-
 mm/slab.c                | 49 ++++++++++++++++----------------
 mm/slob.c                | 59 +++++++++++++++++++++++++++------------
 mm/slub.c                | 60 ++++++++++++++++++++--------------------
 5 files changed, 115 insertions(+), 73 deletions(-)

-- 
2.21.0