Re: [Xen-devel] arm: xl vcpu-pin leads to oom-killer slashing processes

[Juergen Gross <jgross@xxxxxxxx>]

On 12/13/18 3:13 PM, Andrii Anisov wrote:
> Hello All,
>
> OK, I've discovered a mechanism of the issue.
> It is  because of `d->max_pages = ~0U;` in a `construct_dom0()`.
> When I do vcpu-pin, libxl updates memory nodes in xenstore for Dom0. 
> Then kernel watch sees those changes and trying to set new target for 
> ballon, but the target becomes extremely high, and baloon sucks all the 
> pages.
> In my kernel (4.14) in `watch_target()` function there is a code:
>
>          target_diff = xen_pv_domain() ? 0
>                  : static_max - balloon_stats.target_pages;
>
> Here we have `xen_pv_domain()` equal to zero, so `target_diff` big. 
> Then, few lines below:
>      balloon_set_new_target(new_target - target_diff);
>
> `balloon_set_new_target()` receives a value wrapped over 64bit what 
> kills the system.
> Now I'm looking for an appropriate kernel patch for the kernel, to fix 
> that. Any suggestions?
You should use linux kernel commit 3596924a233e45aa918.


Juergen

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