Re: [PATCH v2 2/2] mm/vmpressure: split v1 userspace eventfd code into vmpressure-v1.c

[Usama Arif]

On 29/06/2026 14:34, Michal Koutný wrote:
> On Mon, Jun 29, 2026 at 05:59:37AM -0700, Usama Arif <usama.arif@xxxxxxxxx> wrote:
>> This split is the first step toward eventually making vmpressure
>> CONFIG_MEMCG_V1 only. The v2 in-kernel socket pressure path
>> (tree=false) cannot be removed today immediately: PSI is not an
>> exact replacement for vmpressure, and switching networking socket-buffer
>> back-off to PSI
> 
> (Here I understand PSI is a different and differntly scope metric) but
> what does it mean when you write that tree=false cannot be removed but
> the other patch bails out from vmpressure() (i.e. nothing is updated
> anyway)?
So the first patch bails out for cgroup v2 for tree = true only.
For tree = false, it doesn't bail out, and is still used for networking
socket-buffer back-off. I think that is a whole another scope of work
switching to PSI. Hope that makes sense?

Thanks,
Usama