[PATCH v4 0/7] Make balloon drivers memory changes known to the rest of the kernel

[Alexander Atanasov <alexander.atanasov@xxxxxxxxxxxxx>]

Currently balloon drivers (Virtio,XEN, HyperV, VMWare, ...)
inflate and deflate the guest memory size but there is no
way to know how much the memory size is changed by them.

A common use of the ballooning is to emulate [1]
hot plug and hot unplug - due to the complexity of the later.
Hotplug has a notifier and one can also check the updated
memory size.

To improve this add InflatedTotal and InflatedFree
to /proc/meminfo and implement a balloon notifier.

Amount of inflated memory can be used:
 - si_meminfo(..) users can improve calculations
 - adjust cache/buffer sizes
 - adjust object/connection limits
 - as a hint for the oom a killer
 - by user space software that monitors memory pressure

Alexander Atanasov (7):
  Make place for common balloon code
  Enable balloon drivers to report inflated memory
  Display inflated memory to users
  drivers: virtio: balloon - update inflated memory
  Display inflated memory in logs
  drivers: vmware: balloon - report inflated memory
  drivers: hyperv: balloon - report inflated memory

 Documentation/filesystems/proc.rst            |  6 +++
 MAINTAINERS                                   |  4 +-
 arch/powerpc/platforms/pseries/cmm.c          |  2 +-
 drivers/hv/hv_balloon.c                       | 11 +++++
 drivers/misc/vmw_balloon.c                    |  6 ++-
 drivers/virtio/virtio_balloon.c               |  7 +++-
 fs/proc/meminfo.c                             | 10 +++++
 .../linux/{balloon_compaction.h => balloon.h} | 30 ++++++++++----
 lib/show_mem.c                                |  8 ++++
 mm/Makefile                                   |  2 +-
 mm/{balloon_compaction.c => balloon.c}        | 40 +++++++++++++++++--
 mm/migrate.c                                  |  1 -
 mm/vmscan.c                                   |  1 -
 13 files changed, 110 insertions(+), 18 deletions(-)
 rename include/linux/{balloon_compaction.h => balloon.h} (86%)
 rename mm/{balloon_compaction.c => balloon.c} (88%)

v4:
 - add support in hyperV and vmware balloon drivers
 - display balloon memory in show_mem so it is logged on OOM and on sysrq
v3:
 - added missed EXPORT_SYMBOLS
Reported-by: kernel test robot <lkp@xxxxxxxxx>
 - instead of balloon_common.h just use balloon.h (yes, naming is hard)
 - cleaned up balloon.h - remove from files that do not use it and
   remove externs from function declarations
v2:
 - reworked from simple /proc/meminfo addition

Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Wei Liu <wei.liu@xxxxxxxxxx>
Cc: Nadav Amit <namit@xxxxxxxxxx>
Cc: pv-drivers@xxxxxxxxxx
Cc: Jason Wang <jasowang@xxxxxxxxxx>
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
Cc: Dexuan Cui <decui@xxxxxxxxxxxxx>
Cc: linux-hyperv@xxxxxxxxxxxxxxx
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx

1. https://lore.kernel.org/lkml/f0f12c84-a62e-5f8b-46ab-a651fe8f8589@xxxxxxxxxx/

base-commit: 2bca25eaeba6190efbfcb38ed169bd7ee43b5aaf
-- 
2.31.1