[RFCv3 0/5] enable migration of driver pages

[Gioh Kim]

From: Gioh Kim <gurugio@xxxxxxxxxxx>

Hello,

This series try to enable migration of non-LRU pages, such as driver's page.

My ARM-based platform occured severe fragmentation problem after long-term
(several days) test. Sometimes even order-3 page allocation failed. It has
memory size 512MB ~ 1024MB. 30% ~ 40% memory is consumed for graphic processing
and 20~30 memory is reserved for zram.

I found that many pages of GPU driver and zram are non-movable pages. So I
reported Minchan Kim, the maintainer of zram, and he made the internal 
compaction logic of zram. And I made the internal compaction of GPU driver.

They reduced some fragmentation but they are not enough effective.
They are activated by its own interface, /sys, so they are not cooperative
with kernel compaction. If there is too much fragmentation and kernel starts
to compaction, zram and GPU driver cannot work with the kernel compaction.

This patch set combines 5 patches.

1. patch 1/5: get inode from anon_inodes
This patch adds new interface to create inode from anon_inodes.

2. patch 2/5: framework to isolate/migrate/putback page
Add isolatepage, putbackpage into address_space_operations
and wrapper function to call them

3. patch 3/5: apply the framework into balloon driver
The balloon driver is applied into the framework. It gets a inode
from anon_inodes and register operations in the inode.
Any other drivers can register operations via inode like this
to migrate it's pages.

4. patch 4/5: compaction/migration call the generic interfaces
Compaction and migration pages call the generic interfaces of the framework,
instead of calling balloon migration directly.

5. patch 5/5: remove direct calling of migration of driver pages
Non-lru pages are migrated with lru pages by move_to_new_page().

This patch set is tested:
- turn on Ubuntu 14.04 with 1G memory on qemu.
- do kernel building
- after several seconds check more than 512MB is used with free command
- command "balloon 512" in qemu monitor
- check hundreds MB of pages are migrated

My thanks to Konstantin Khlebnikov for his reviews of the v2 patch set.
Most of the changes were based on his feedback.

Changes since v2:
- change the name of page type from migratable page into mobile page
- get and lock page to isolate page
- add wrapper interfaces for page->mapping->a_ops->isolate/putback
- leave balloon pages marked as balloon

This patch-set is based on v4.1

Gioh Kim (5):
  fs/anon_inodes: new interface to create new inode
  mm/compaction: enable mobile-page migration
  mm/balloon: apply mobile page migratable into balloon
  mm/compaction: call generic migration callbacks
  mm: remove direct calling of migration

 drivers/virtio/virtio_balloon.c        |  3 ++
 fs/anon_inodes.c                       |  6 +++
 fs/proc/page.c                         |  3 ++
 include/linux/anon_inodes.h            |  1 +
 include/linux/balloon_compaction.h     | 15 +++++--
 include/linux/compaction.h             | 76 ++++++++++++++++++++++++++++++++++
 include/linux/fs.h                     |  2 +
 include/linux/page-flags.h             | 19 +++++++++
 include/uapi/linux/kernel-page-flags.h |  1 +
 mm/balloon_compaction.c                | 71 ++++++++++---------------------
 mm/compaction.c                        |  8 ++--
 mm/migrate.c                           | 24 +++--------
 12 files changed, 154 insertions(+), 75 deletions(-)

-- 
2.1.4

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