Re: [PATCH v4 0/5] memcg: nmi-safe kmem charging

[Shakeel Butt]

On Mon, Jun 02, 2025 at 04:45:31PM +0200, Michal Koutný wrote:
> Hello Shakeel.
> 
> On Sun, May 18, 2025 at 11:31:37PM -0700, Shakeel Butt <shakeel.butt@xxxxxxxxx> wrote:
> > Users can attached their BPF programs at arbitrary execution points in
> > the kernel and such BPF programs may run in nmi context. In addition,
> > these programs can trigger memcg charged kernel allocations in the nmi
> > context. However memcg charging infra for kernel memory is not equipped
> > to handle nmi context for all architectures.
> 
> How much memory does this refer to? Is it unbound (in particular for
> non-privileged eBPF)? Or is it rather negligible? (I assume the former
> to make the series worth it.)
> 

It depends on the BPF program and thus can be arbitrarily large. So,
irrespective of privileged or non-privileged BPF programs, they can
allocate large amount of memory to maintain monitoring or debugging (or
for some other use-case) information.