Re: Linux 5.13-rc6 regression to 5.12.x: kernel OOM and panic during kernel boot in low memory Xen VM's (256MB assigned memory).

[Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>]

On 18/06/2021 03.06, Sander Eikelenboom wrote:
> On 17/06/2021 21:39, Sander Eikelenboom wrote:

> 
> OK, done some experimentation and it seems with 256M assigned to the VM
> it was almost at the edge of OOM with the 5.12 kernel as well in the
> config I am using it.
> With v5.12 when I assign 240M it boots, with 230M it doesn't. With 5.13
> the tipping point seems to be around 265M and 270M, so my config was
> already quite close to the edge.
> 
> The "direct kernel boot" feature I'm using just seems somewhat memory
> hungry, but using another compression algorithm for the kernel and
> initramfs already helped in my case.
> 
> So sorry for the noise, clearly user-error.

Hm, perhaps, but I'm still a bit nervous about that report from Oliver
Sang/kernel test robot, which was for a VM equipped with 16G of memory.
But despite quite a few attempts, I haven't been able to reproduce that
locally, so unfortunately I have no idea what's going on.

Rasmus