Re: [PATCH v3] xen/balloon: add late_initcall_sync() for initial ballooning done

On 10/29/21 10:20 AM, Juergen Gross wrote:

--- a/Documentation/ABI/stable/sysfs-devices-system-xen_memory +++ b/Documentation/ABI/stable/sysfs-devices-system-xen_memory @@ -84,3 +84,13 @@ Description: Control scrubbing pages before returning them to Xen for others domains use. Can be set with xen_scrub_pages cmdline parameter. Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT.

+What: /sys/devices/system/xen_memory/xen_memory0/boot_timeout +Date: November 2021 +KernelVersion: 5.16 +Contact: xen-devel@lists.xenproject.org +Description:

• The time (in seconds) to wait before giving up to boot in case
  

• initial ballooning fails to free enough memory. Applies only
  

• when running as HVM or PVH guest and started with less memory
  

• configured than allowed at max.
  

How is this going to be used? We only need this during boot.

• state = update_schedule(state);
  

• balloon_state = update_schedule(balloon_state);
  

Now that balloon_state has whole file scope it can probably be updated inside update_schedule().

• while ((credit = current_credit()) < 0) {

• if (credit != last_credit) {
  

• 	last_changed = jiffies;
  

• 	last_credit = credit;
  

• }
  

• if (balloon_state == BP_ECANCELED) {
  

What about other states? We are really waiting for BP_DONE, aren't we?

-boris

• 	pr_warn_once("Initial ballooning failed, %ld pages need to be freed.\n",
  

• 		     -credit);
  

• 	if (jiffies - last_changed >=
  

• 	    HZ * balloon_stats.boot_timeout)
  

• 		panic("Initial ballooning failed!\n");
  

• }