lkml.org 
[lkml]   [2013]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/1] xen/balloon: Enforce various limits on target
On Mon, Mar 04, 2013 at 10:14:51PM +0100, Daniel Kiper wrote:
> This patch enforces on target limit statically defined in Linux Kernel
> source and limit defined by hypervisor or host.
>
> Particularly this patch fixes bug which led to flood
> of dom0 kernel log with messages similar to:
>
> System RAM resource [mem 0x1b8000000-0x1bfffffff] cannot be added
> xen_balloon: reserve_additional_memory: add_memory() failed: -17
>
> It does not allow balloon driver to execute infinite
> loops when target exceeds limits in other cases too.
>
> Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>

One nitpick below; David, could you take a look just for a extra
set of eyes.
> ---
> drivers/xen/balloon.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 46 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> index a56776d..07da753 100644
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -65,6 +65,7 @@
> #include <xen/balloon.h>
> #include <xen/features.h>
> #include <xen/page.h>
> +#include <xen/xenbus.h>
>
> /*
> * balloon_process() state:
> @@ -490,11 +491,55 @@ static void balloon_process(struct work_struct *work)
> mutex_unlock(&balloon_mutex);
> }
>
> -/* Resets the Xen limit, sets new target, and kicks off processing. */
> +/* Enforce limits, set new target and kick off processing. */
> void balloon_set_new_target(unsigned long target)
> {
> + domid_t domid = DOMID_SELF;
> + int rc;
> + unsigned long long host_limit;
> +
> + /* Enforce statically defined limit. */
> + target = min(target, MAX_DOMAIN_PAGES);
> +
> + if (xen_initial_domain()) {
> + rc = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
> +
> + /* Limit is not enforced by hypervisor. */
> + if (rc == -EPERM)
> + goto no_host_limit;
> +
> + if (rc <= 0) {
> + pr_info("xen_balloon: %s: Initial domain target limit "
> + "could not be established: %i\n", __func__, rc);

Probably pr_debug. As this means the user booted without dom0_mem_max argument.
(B/c rc == UINT_MAX) I would say if you can check for that and it as part of
if (rc == -EPERM) check.


> + goto no_host_limit;
> + }
> +
> + host_limit = rc;
> + } else {
> + rc = xenbus_scanf(XBT_NIL, "memory", "static-max",
> + "%llu", &host_limit);
> +
> + if (rc != 1) {
> + pr_info("xen_balloon: %s: Guest domain target limit "
> + "could not be established: %i\n", __func__, rc);
> + goto no_host_limit;
> + }
> +
> + /*
> + * The given memory target limit value is in KiB, so it needs
> + * converting to pages. PAGE_SHIFT converts bytes to pages,
> + * hence PAGE_SHIFT - 10.
> + */
> + host_limit >>= (PAGE_SHIFT - 10);
> + }
> +
> + /* Enforce hypervisor/host defined limit. */
> + target = min(target, (unsigned long)host_limit);
> +
> +no_host_limit:
> /* No need for lock. Not read-modify-write updates. */
> balloon_stats.target_pages = target;
> +
> schedule_delayed_work(&balloon_worker, 0);
> }
> EXPORT_SYMBOL_GPL(balloon_set_new_target);
> --
> 1.7.10.4
>


\
 
 \ /
  Last update: 2013-03-05 21:02    [W:0.074 / U:0.124 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site