[PATCH v2 0/4] track memory used by balloon drivers

[Nico Pache <npache@redhat.com>]

This series introduces a way to track memory used by balloon drivers.

Add a NR_BALLOON_PAGES counter to track how many pages are reclaimed by the
balloon drivers. First add the accounting, then updates the balloon drivers
(virtio, Hyper-V, VMware, Pseries-cmm, and Xen) to maintain this counter. The
virtio, Vmware, and pseries-cmm balloon drivers utilize the balloon_compaction
interface to allocate and free balloon pages. Other balloon drivers will have to
maintain this counter manually.

This makes the information visible in memory reporting interfaces like
/proc/meminfo, show_mem, and OOM reporting.

This provides admins visibility into their VM balloon sizes without
requiring different virtualization tooling. Furthermore, this information
is helpful when debugging an OOM inside a VM.

V2 changes:
- Add counter to the balloon_compaction interface
- Dropped patches for virtio and VMware as they use balloon_compaction interface

Tested: virtio_balloon, run stress-ng, inflate balloon, oom prints
Signed-off-by: Nico Pache <npache@redhat.com>

Nico Pache (4):
  meminfo: add a per node counter for balloon drivers
  balloon_compaction: update the NR_BALLOON_PAGES state
  hv_balloon: update the NR_BALLOON_PAGES state
  xen: balloon: update the NR_BALLOON_PAGES state

 drivers/hv/hv_balloon.c | 2 ++
 drivers/xen/balloon.c   | 4 ++++
 fs/proc/meminfo.c       | 2 ++
 include/linux/mmzone.h  | 1 +
 mm/balloon_compaction.c | 2 ++
 mm/show_mem.c           | 4 +++-
 mm/vmstat.c             | 1 +
 7 files changed, 15 insertions(+), 1 deletion(-)

-- 
2.48.1