"Denis V. Lunev" <d...@parallels.com> writes:
> From: Raushaniya Maksudova <rmaksud...@parallels.com>
>
> 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 makes some amount of sense.
But I suggest a few minor changes:
> +static int oom_vballoon_pages = OOM_VBALLOON_DEFAULT_PAGES;
> +module_param(oom_vballoon_pages, int, S_IRUSR | S_IWUSR);
> +MODULE_PARM_DESC(oom_vballoon_pages, "pages to free on OOM");
Since this is already prefixed with "virtio_balloon." I suggest just
calling it "oom_pages".
> +static int virtballoon_oom_notify(struct notifier_block *self,
> + unsigned long dummy, void *parm)
> +{
> + unsigned int num_freed_pages;
> + unsigned long *freed = (unsigned long *)parm;
> + struct virtio_balloon *vb = container_of((struct notifier_block *)self,
> + struct virtio_balloon, nb);
Why cast self here?
> + num_freed_pages = leak_balloon(vb, oom_vballoon_pages);
> + update_balloon_size(vb);
> + *freed += num_freed_pages;
> +
> + return NOTIFY_OK;
> +}
Cheers,
Rusty.
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