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| author | Raushaniya Maksudova <rmaksudova@parallels.com> | 2014-11-10 00:06:29 +0100 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2014-11-11 07:39:58 +0100 |
| commit | 5a10b7dbf904bfe01bb9fcc6298f7df09eed77d5 (patch) | |
| tree | cd8f823828105f03c4ae7149217f827f3d82c39d /include/uapi | |
| parent | virtio_balloon: return the amount of freed memory from leak_balloon() (diff) | |
| download | linux-5a10b7dbf904bfe01bb9fcc6298f7df09eed77d5.tar.xz linux-5a10b7dbf904bfe01bb9fcc6298f7df09eed77d5.zip | |
virtio_balloon: free some memory from balloon on OOM
Excessive virtio_balloon inflation can cause invocation of OOM-killer,
when Linux is under severe memory pressure. Various mechanisms are
responsible for correct virtio_balloon memory management. Nevertheless
it is often the case that these control tools does not have enough time
to react on fast changing memory load. As a result OS runs out of memory
and invokes OOM-killer. The balancing of memory by use of the virtio
balloon should not cause the termination of processes while there are
pages in the balloon. Now there is no way for virtio balloon driver to
free some memory at the last moment before some process will be get
killed by OOM-killer.
This does not provide a security breach as balloon itself is running
inside guest OS and is working in the cooperation with the host. Thus
some improvements from guest side should be considered as normal.
To solve the problem, introduce a virtio_balloon callback which is
expected to be called from the oom notifier call chain in out_of_memory()
function. If virtio balloon could release some memory, it will make
the system to return and retry the allocation that forced the out of
memory killer to run.
Allocate virtio feature bit for this: it is not set by default,
the the guest will not deflate virtio balloon on OOM without explicit
permission from host.
Signed-off-by: Raushaniya Maksudova <rmaksudova@parallels.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'include/uapi')
| -rw-r--r-- | include/uapi/linux/virtio_balloon.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h index 5e26f61b5df5..be40f7059e93 100644 --- a/include/uapi/linux/virtio_balloon.h +++ b/include/uapi/linux/virtio_balloon.h @@ -31,6 +31,7 @@ /* The feature bitmap for virtio balloon */ #define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */ #define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */ +#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */ /* Size of a PFN in the balloon interface. */ #define VIRTIO_BALLOON_PFN_SHIFT 12 |